Time Calculator
Add or subtract hours, minutes and seconds — or find the exact duration between two clock times, including overnight spans — with instant, accurate answers.
Calculate time
Pick a mode, then enter your durations, clock times, or dates.
- Every duration is converted to seconds before it is combined: 2:30:00 + 1:45:30 runs as 9,000 + 6,330 = 15,330 seconds, then converts back to 4:15:30 — that is why minutes and seconds never spill past 60 by accident.
- If the “To” time is earlier than the “From” time, the span is treated as overnight — the end time rolls past midnight into the next day, which is how shift and sleep spans are usually meant.
- The Expression mode takes strings like “1d 2h 3m 4s + 4h 5s − 2030s”: d, h, m and s units with + and − between them, applied in order to a running total.
See the duration on a timeline
A visual view of your result — durations measured against a 24-hour day, clock spans plotted on a 24-hour strip.
More math tools to try
Handy calculators for numbers and everyday math.
How to do time math in seconds
Three steps, instant answers.
Add or subtract two durations, or measure the gap between two clock times.
Type durations in h/m/s, or pick two clock times. Answers update as you type.
The result shows as h:mm:ss, plus totals in seconds, minutes, hours and days.
⏱How time arithmetic works
Everything is converted to seconds first — the only unit where time adds cleanly. Then the total is converted back to h:mm:ss.
(b) clock span: duration = B − A (if B < A, use B+24h)
Overnight rule: clock times are read as the same day by default. When the end time is earlier than the start time, the calculator assumes the span crosses midnight and adds 24 hours to the end time — so 22:00 → 02:00 = 4:00:00, not a negative value. For a true same-day span where the end is earlier, that combination simply cannot happen on one calendar day, which is why the overnight reading is the useful default.
Worked example: 2:30:00 + 1:45:30 → 9,000 s + 6,330 s = 15,330 s → 4:15:30. And 5:00:00 − 7:30:00 → −9,000 s → −2:30:00 (the minus sign marks a negative duration).
A shift from 22:00 to 02:00 crosses midnight, so the span is (02:00 + 24:00) − 22:00 = 4:00:00. This convention matches how payroll, shift planning and sleep trackers treat evening-to-morning ranges. On the 24-hour timeline above, an overnight span shows as two segments: from the start time to midnight, and from midnight to the end time.
Hours and minutes do not borrow or carry the way decimal digits do — 1 hour is 60 minutes, not 100. By converting every duration to total seconds, addition and subtraction become ordinary arithmetic. Normalizing then splits the total back out: hours = ⌊s ÷ 3600⌋, minutes = ⌊(s mod 3600) ÷ 60⌋, seconds = s mod 60. That is also why inputs like 90 seconds work fine — they are just 90 seconds.
A clock time is a point on the dial (8:15 AM). A duration is a length of time (4:30:00). Adding two clock times is meaningless, but adding or subtracting two durations is always valid. The “Time difference” tab exists precisely to convert two points (clock times) into one length (a duration).
The complete guide to time calculations
Everything about adding and subtracting time — durations, clock spans, date math, and the sexagesimal system that makes it tricky.
⏱️How time arithmetic actually works
Time math is hard because time isn’t decimal — it’s sexagesimal (base 60). A time calculator — sometimes called a time duration calculator — converts everything to the smallest unit, does plain arithmetic, then converts back: total seconds = days×86,400 + hours×3,600 + minutes×60 + seconds.
Most people who land here need one of three tools, so I built all three into this one page. As an hours calculator — an hour calculator or clock calculator, same job — it adds and subtracts durations: use it as a time adder (an add time calculator) whenever shift lengths, study sessions or recipe stages need totalling. As a finder of the time between times, it measures the span between two clock times, overnight included. And because every field takes hours and minutes together, it doubles as an hours and minutes calculator, with seconds when you need them. The fourth job — the one behind most visits — is time clock work: totalling a working day or week for a timesheet, which gets its own section further down.
Worked example: to add time durations 2:30:00 + 1:45:30. Convert: 9,000 s + 6,330 s = 15,330 s. Convert back: 15,330 ÷ 3,600 = 4 h remainder 930 s → 930 ÷ 60 = 15 m remainder 30 s → 4:15:30. That’s 255.5 minutes, 4.26 hours, or 0.18 days.
With days: 1 day 2:00:00 + 3:00:00 = 93,600 s + 10,800 s = 104,400 s → 29:00:00 (1,740 minutes, 29 hours, 1.21 days). The calculator keeps hours unpadded above 24 (29:00:00, not 1d 5:00:00) so multi-day totals stay readable — the day count appears separately in the stats.
Subtraction can go negative: 5:00:00 − 7:30:00 = −2:30:00 (shown with a leading minus). Overflow is normalized automatically: 90 seconds becomes 1:30, 75 minutes becomes 1:15:00.
Borrowing and carrying, by hand: to subtract 1:45:30 from 2:30:00, start with seconds: 0 − 30 won’t go, so borrow 1 minute (60 s): 60 − 30 = 30 s, minutes drop to 29. Minutes: 29 − 45 won’t go, borrow 1 hour (60 m): 89 − 45 = 44 m, hours drop to 1. Hours: 1 − 1 = 0. Result: 0:44:30. Check: 0:44:30 + 1:45:30 = 2:30:00 ✓. Addition carries the other way: 45 s + 30 s = 75 s → carry 1 minute, keep 15 s.
📏Time units — the complete table
Every unit in the calculator, with exact conversion factors:
| Unit | Equals | In seconds |
|---|---|---|
| 1 day | 24 hours | 86,400 |
| 1 hour | 60 minutes | 3,600 |
| 1 minute | 60 seconds | 60 |
| 1 second | — | 1 |
| 1 week | 7 days | 604,800 |
Bigger units: a week is 604,800 s; a 30-day month is 2,592,000 s; a 365-day year is 31,536,000 s (≈31.6 million — handy for Fermi estimates). An average 73-year human life is about 2.3 billion seconds.
Handy reference values: a day has 86,400 seconds — the answer to “how many seconds in a day” — an 8-hour workday is 28,800 seconds; a 40-hour week is 144,000 seconds. The stats under every result show your answer in all four units at once, so you never have to convert manually.
🌙Clock time vs duration — and the overnight rule
A duration is a length of time (2 hours 30 minutes). A clock time is a point in time (2:30 PM). The “Time difference” mode answers “time between two times” — the span between two clock times — the classic use case is shifts and sleep.
The overnight rule: if the “To” time is earlier than the “From” time, the calculator assumes the span crosses midnight. 22:00 → 02:00 = 4:00:00 (the end rolls into the next day). This is the right default for night shifts and sleep tracking — a 10 PM to 2 AM span is obviously 4 hours, not −20.
Same-day spans are straightforward: 08:00 → 17:00 = 9:00:00. The timeline visualization plots your span on a 24-hour strip so you can see exactly where it falls — overnight spans show as two segments split at midnight.
Split shifts and broken days: a day with two work blocks — 08:00–12:00 and 13:00–17:00 — is two spans: 4:00:00 + 4:00:00 = 8:00:00. Compute each in Time difference mode, then add them in the durations tab. For sleep, 23:30 → 06:45 overnight = 7:15:00; a week of it is 7 × 7:15 = 50:45:00, just over 50 hours.
🕐How to calculate time between two clock times
Half the questions sent to this page are really one question: how much time passed between then and now? That makes the Time difference mode an elapsed time calculator, a time difference calculator and a time span calculator in one — three names for the same subtraction. Here is the method I use by hand, so you can sanity-check any answer the tool gives you.
Step 1: convert both clock times to minutes since midnight. 9:47 AM is 9 × 60 + 47 = 587 minutes; 6:25 PM is 18 × 60 + 25 = 1,105 minutes. Step 2: subtract: 1,105 − 587 = 518 minutes. Step 3: convert back — 518 ÷ 60 = 8 hours with 38 left over, so the elapsed time is 8:38. If step 2 ever goes negative, the span crossed midnight: add 1,440 (the minutes in a day) before converting back. An overnight span works exactly the same way — 10:15 PM to 6:45 AM is (405 + 1,440) − 1,335 = 510 minutes = 8:30.
Minutes-and-seconds precision: if you searched “time calculator minutes and seconds”, the durations tab is your mode — every field accepts seconds, and decimals too. Sports timing is the classic case: two laps of 1:23:45 and 0:58:20 total 5,025 + 3,500 = 8,525 seconds = 2:22:05, with no rounding to whole minutes anywhere. The same precision serves lap splits, experiment timings and media edits — anywhere a span is meaningless without its seconds.
📅Date math — adding time to a calendar date
The “Date math” mode answers “what date and time is X hours from now?” — essential for deadlines, scheduling, and project planning. Pick a start date and time, choose add or subtract, enter a duration, and get the resulting date and time.
Examples: 2026-01-15 10:00 + 36 hours → 2026-01-16 22:00. 2026-01-31 12:00 + 1 day → 2026-02-01 12:00 (month rollover handled automatically).
Wall-clock note: the math uses wall-clock arithmetic — days and hours are added as displayed on a clock. Daylight-saving transitions are not adjusted: adding 24 hours across a “spring forward” still lands at the same clock time the next day. For scheduling and deadlines this is usually what you want; for precise elapsed-time measurement across a DST boundary, be aware of the one-hour difference.
Month lengths and leap years: date math respects the real calendar — adding 1 month isn’t a fixed duration, so the calculator works in days/hours/minutes/seconds rather than months. Adding 30 days to 2026-01-15 gives 2026-02-14 (January has 31 days); adding 30 days to 2026-02-15 gives 2026-03-17 (February 2026 has 28 days). Leap years add February 29 automatically: 2028-02-28 12:00 + 1 day → 2028-02-29 12:00.
Practical uses: project deadlines (kickoff + 90 days), subscription renewals, medication schedules (every 8 hours from first dose), travel itineraries with layovers. For anything involving months rather than days — loan terms, age calculations, subscription billing — use a dedicated date calculator, since months have uneven lengths and date math here is day-based by design.
⌨️The expression evaluator
For power users, the Expression mode evaluates one-line time math: type something like 1d 2h 3m 4s + 4h 5s − 2030s and get the answer instantly. Suffixes: d days, h hours, m minutes, s seconds. Operators: + and −. Spaces are optional — “2h30m” works the same as “2h 30m”.
Worked example: 1d 2h 3m 4s + 4h 5s − 2030s. In seconds: 93,784 + 14,405 − 2,030 = 106,159 s → 1d 5h 29m 19s. (If you see a different figure quoted elsewhere for this expression, 106,159 s is the verified correct value.)
Invalid input shows an inline error instead of a wrong answer — the parser requires every token to be a number+suffix or an operator, so typos can’t silently corrupt the result.
More examples: 2h30m + 90s = 9,090 s = 2:31:30. 1d – 12h = 43,200 s = 12:00:00. 1.5h + 30m = 7,200 s = 2:00:00. Decimals work on any unit, and a leading minus negates the first term (-30m + 1h = 30:00). The evaluator is deliberately simple — no parentheses, no multiplication — because time math is almost always addition and subtraction.
💼Time math for work — timesheets and payroll
Timesheets are the #1 real-world use of a time duration calculator. A typical week: Mon 8:00–17:00 (9:00), Tue 8:30–17:00 (8:30), Wed 8:00–16:30 (8:30), Thu 8:00–17:30 (9:30), Fri 8:00–15:00 (7:00). Add them: 9:00 + 8:30 + 8:30 + 9:30 + 7:00 = 42:30:00 = 153,000 seconds = 2,550 minutes = 42.5 hours.
Decimal hours for payroll: payroll wants 42.5, not 42:30. Convert: minutes ÷ 60. So 8:30 → 8.5 h, 7:45 → 7.75 h, 0:15 → 0.25 h. The calculator’s “Total hours” stat does this automatically (42.5 for the week above). Common payroll rounding: nearest quarter hour (7-minute rule) — 8:07 rounds to 8:00, 8:08 rounds to 8:15.
Overtime math: with a 40-hour threshold, the week above has 2.5 overtime hours. At time-and-a-half on a $20/h base: 40 × $20 + 2.5 × $30 = $800 + $75 = $875. Night-shift differentials add a premium per overnight hour — the overnight rule in the Time difference mode computes those spans correctly.
Project estimation: add task durations the same way. Design 12:30 + build 38:15 + review 4:45 + buffer 8:00 = 63:30:00 ≈ 64 hours ≈ 8 working days. The Days field handles multi-day tasks directly: 2d 4:00:00 + 1d 6:30:00 = 3d 10:30:00.
🏛️Why time is base 60 — a short history
Hours, minutes and seconds are base 60 because the Sumerians (c. 2000 BCE) counted in sixties — 60 divides evenly by 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30, making fractions easy without decimals. The Egyptians split daylight into 12 parts (the 12-hour clock), and the 24-hour day, 60-minute hour and 60-second minute were standardized for astronomy long before mechanical clocks.
This is why time math feels unnatural: every other quantity you compute daily is decimal, but time carries a 4,000-year-old number system. The calculator exists precisely because borrowing and carrying in base 60 — 90 seconds → 1:30, 75 minutes → 1:15:00 — is error-prone by hand. Computers convert to seconds, add, and convert back; humans should too (or just use the tool).
Metric time was actually proposed during the French Revolution (10-hour days, 100-minute hours) — and failed completely. Base 60 survived because 60’s divisibility beats 10’s simplicity for everyday fractions: a third of an hour is a clean 20 minutes, while a third of a decimal hour is 0.333…
The second itself was redefined in 1967 — no longer 1/86,400 of a day, but 9,192,631,770 oscillations of a cesium-133 atom. Your phone’s clock is a distant descendant of that definition, synced over networks to atomic time. Yet the hours and minutes it displays are still Sumerian. Every time you add 2:30 and 1:45, you’re doing arithmetic in a 4,000-year-old base — which is exactly why the calculator does the carrying for you.
🌍Time zones and scheduling across zones
When collaborators span time zones, subtract clock times across zones the same way: convert both to UTC first, then difference. A 9:00 AM New York meeting is 2:00 PM London (UTC+0 vs UTC−5 in winter) — the 5-hour gap is just 14:00 − 09:00.
Finding overlap: New York (9–17) and London (9–17 local) overlap 9:00–12:00 New York time = 14:00–17:00 London — a 3-hour window. Add Tokyo (9–17 JST = 19:00–03:00 ET previous day) and the three-way overlap shrinks to roughly 8:00–9:00 ET. The Time difference mode computes each leg; do the UTC conversion first.
Flight math: a flight departs 14:00 (zone A) and lands 21:45 local (zone B, 3 hours ahead). Convert the arrival to zone A: 21:45 − 3:00 = 18:45. Flight time: 18:45 − 14:00 = 4:45:00. The rule: always convert both times to the same zone before subtracting; the calculator handles the arithmetic once the inputs share a zone.
Daylight saving adds another wrinkle: New York–London is 5 hours in winter, 4 in summer (different changeover weekends create 2–3 weeks of shifted gaps each spring and fall). For recurring meetings, recheck the overlap after each DST transition.
🏃Sports, cooking and everyday timing
Beyond timesheets, duration math runs daily life:
- Running pace: a 5K in 27:30 is 27.5 × 60 = 1,650 s ÷ 5 = 5:30 per km. Marathon target 4:00:00 over 42.195 km → 14,400 ÷ 42.195 ≈ 5:41 per km.
- Cooking: chicken needs 1:15 in the oven, potatoes 0:50, resting 0:15. Work backwards from serving at 19:30: rest starts 19:15, potatoes in at 18:25, chicken in at 18:00. The Date math mode does this: 19:30 − 1:30 total = 18:00 start.
- Media: a 42:30 episode at 1.25× speed takes 42.5 ÷ 1.25 = 34:00. A 10-episode season: 425 min → 340 min, saving 85 minutes.
- Sleep: 7.5 hours is 5 full 90-minute sleep cycles. Bed at 23:00 → wake 06:30. The overnight span in Time difference mode: 23:00 → 06:30 = 7:30:00.
📊Reading your results — all four units
Every calculation shows four totals underneath: seconds, minutes, hours, days. They’re the same answer in different units — pick whichever fits the job:
- Seconds — for programming, timers, and precise measurement. 15,330 s is exact; 4.26 h is rounded.
- Minutes — for billing in minute increments, cooking, and workouts. 255.5 min reads naturally.
- Hours — for payroll (decimal hours), project estimates, and timesheets. 42.5 h, not 42:30.
- Days — for long durations and SLAs. 1.21 days beats “29 hours” when the audience thinks in days.
The timeline visualization puts durations in context: results under 24 hours show as a share of a day (4:15:30 fills 17.7% of the bar), while clock spans plot on a 24-hour strip with overnight spans split at midnight. It’s a quick sanity check — if the bar looks wrong, recheck the inputs.
Copy button: the “copy result” button grabs the full equation (e.g. “2:30:00 + 1:45:30 = 4:15:30”) for pasting into timesheets, emails, or tickets — no retyping, no transcription errors.
🕗12-hour vs 24-hour clock
The calculator uses 24-hour time (08:00, 17:00, 23:30) because it’s unambiguous — but much of daily life runs on 12-hour AM/PM. The conversions:
| 12-hour | 24-hour | Note |
|---|---|---|
| 12:00 AM (midnight) | 00:00 | The tricky one — midnight is 00:00, not 12:00 |
| 1:00 AM – 11:59 AM | 01:00 – 11:59 | Same numbers |
| 12:00 PM (noon) | 12:00 | Stays 12 |
| 1:00 PM – 11:59 PM | 13:00 – 23:59 | Add 12 |
Memory aid: 12 AM is midnight (the day starts), 12 PM is noon (the sun is up). The #1 scheduling error is a midnight deadline read as noon — a 12-hour mistake. When entering times in the calculator, the time picker uses 24-hour format; type 14:30 for 2:30 PM.
Aviation, hospitals and most of the world run on 24-hour time precisely to kill this ambiguity. If you schedule across teams, write 14:30 instead of 2:30 PM — three fewer characters to misread.
⚠️Common time-math mistakes
- Adding clock times as decimals. 1:30 + 1:30 is 3:00, not 2.60. Never convert h:mm to decimal by concatenating — 1:30 is 1.5 hours, and 1.5 + 1.5 = 3.0. ✓
- Forgetting the overnight rule. A 22:00→06:00 shift is 8 hours, not −16. If your spreadsheet shows a negative, add 24 hours.
- Mixing durations and clock times. “Add 2:30 to 3:00 PM” means 5:30 PM (duration + clock time). “3:00 PM + 2:30 PM” is meaningless — you can’t add two clock times.
- DST surprises. Scheduling across a daylight-saving change? Confirm whether your tool uses wall-clock or elapsed time — they differ by an hour twice a year.
- Rounding timesheet minutes. 1:45 is 1.75 hours for payroll, not 1.45. Multiply minutes by 1/60, don’t just move the decimal point.
💡 Timesheet tip: most payroll systems round to the nearest 15 minutes (7-minute rule). The exact spans from the “Time difference” mode are your starting point — apply your employer’s rounding policy on top.
Time clock & timesheet mode
The Time difference tab doubles as a full time clock calculator — clock in, clock out, lunch off, and a payroll-ready total in decimal hours.
🕐Using this page as a time clock calculator
When I say this page works as a time clock calculator, I mean the Time difference tab is your time clock: type your clock-in time as “From” and your clock-out time as “To”, and the span between them is your shift. That single move turns the page into a timecard calculator and a timesheet calculator — no separate app, no sign-up. Clock in at 8:00 and out at 17:00 and you will see 9:00:00; the four totals underneath give the same shift as 32,400 seconds, 540 minutes, 9 hours or 0.38 days.
Two things make it trustworthy for real timesheets. First, the overnight rule: a night shift from 22:00 to 06:00 reads as 8:00:00, not a negative number, because the tab assumes an end time earlier than the start rolled past midnight. Second, nothing is rounded behind your back — the span is exact to the second, and any rounding for payroll happens where it should: in your employer’s policy, applied by you, on top of an exact figure.
💼Work hours calculator — from one shift to a whole week
Most time calculator work requests I see are really one job: total a week. Treat this page as your work hours calculator and the routine is always the same — measure each day as a clock span, take lunch off, then add the days in the durations tab. Here is a real-shaped week run through this work time calculator, the way I calculate hours for a timesheet:
| Day | In – Out | Lunch | Hours worked |
|---|---|---|---|
| Monday | 8:00 – 17:00 | 30 min | 8.5 |
| Tuesday | 8:15 – 17:15 | 30 min | 8.5 |
| Wednesday | 7:45 – 16:30 | 45 min | 8.0 |
| Thursday | 8:00 – 17:30 | 30 min | 9.0 |
| Friday | 8:30 – 15:00 | 30 min | 6.0 |
| Week total | 40.0 |
As an hours worked calculator the one figure payroll actually wants is the decimal: hours plus minutes ÷ 60. A span of 7:45 becomes 7.75 hours, 8:30 becomes 8.5 — and you never have to do that division yourself, because the “Total hours” stat under every result is already decimal. To calculate hours worked across several days, add the daily spans in the durations tab (8:30 + 8:30 + 8:00 + 9:00 + 6:00 = 40:00:00) and read the same decimal total. If your employer rounds to the nearest quarter hour, round each day first, then add — rounding the weekly total instead can quietly move a quarter hour between weeks.
🍽️Lunch and break deductions
A span is not the same as paid time, and the difference is almost always lunch. Worked the standard way, this is a time card calculator with lunch handled exactly the way payroll handles it: measure the full span, then subtract the unpaid break. Clock 8:00 to 17:00 and the span is 9:00; take off a 30-minute lunch and you worked 8.5 hours. A 60-minute lunch on a 9:00-to-18:00 day gives 9:00 − 1:00 = 8.0 hours. In the tool: run the span in Time difference mode, then subtract the lunch in the durations tab — or simply enter your clock-out 30 minutes earlier.
Paid or unpaid? Under the U.S. Department of Labor’s plain-language summaries, short rest breaks of about 5 to 20 minutes are generally counted as paid working time, while a bona fide meal period — typically at least 30 minutes, with you fully relieved of duty — can be unpaid. Employer policies and state rules vary, so treat that as general information rather than legal advice, and check your own handbook for the policy that applies to you. Whatever the policy, the arithmetic on this page stays the same: exact span first, deduction second, rounding last.
What time will it be…?
Future-time questions — “what time will it be in 30 minutes?” — answered with the Date math tab: a start time plus an offset.
🔮Adding an offset to a clock time
The pattern behind every “what time will it be…” question is one addition: start time + offset, carrying into the hours when the minutes pass 60, and flipping AM to PM (or PM to AM) when you cross 12. So what time will it be in 30 minutes from 12:45 PM? 12:45 + 0:30 = 1:15 PM. And what time will it be in 2 hours from 10:20 AM? 12:20 PM — noon crossed, so AM flips to PM. What time will it be in 3 hours from 11:10 AM? 2:10 PM. Crossing midnight works the same way with the date rolling forward: 11:40 PM + 30 minutes = 12:10 AM the next day.
In the tool, use the Date math tab: pick today’s date, enter the start time, choose “+ Add duration”, and type the offset as a duration — 0 days, 2 hours, 30 minutes. I use it for the everyday versions of this question: when a film that starts at 8:20 PM and runs 2:15 ends (10:35 PM), when a dose taken at 6:45 AM is due again in 8 hours (2:45 PM), or when a 3-hour drive that leaves at 9:15 AM arrives (12:15 PM). Because the tab works on a real calendar date, month ends and leap days are handled for you — the offset just lands where it lands.
Time conversions at a glance
The answers people ask for most — how many minutes in an hour, a day, a week — plus the decimal-hours table payroll runs on.
🔢How many minutes in…?
Ask “how many minutes” about any everyday span and one of these rows is the answer. Read across for the same span in seconds — used this way, the page is a minute calculator (a minutes calculator, whichever you typed) with the arithmetic already done:
| Span | Minutes | Seconds |
|---|---|---|
| 1 hour | 60 | 3,600 |
| 8 hours (a workday) | 480 | 28,800 |
| 12 hours | 720 | 43,200 |
| 24 hours in minutes (a full day) | 1,440 | 86,400 |
| 1 week (168 hours) | 10,080 | 604,800 |
Decimal hours, for payroll: the same spans written the way timesheets want them. 0.10 h = 6 minutes, 0.25 h = 15 minutes, 0.50 h = 30 minutes, 0.75 h = 45 minutes, 0.90 h = 54 minutes — always minutes ÷ 60, never a moved decimal point. And if a 24-hour-clock time is what brought you here: 13:15 is 1:15 PM, 17:30 is 5:30 PM, 18:45 is 6:45 PM, 20:00 is 8:00 PM and 23:59 is 11:59 PM — for PM times past noon, subtract 12 and add PM.
Time calculator FAQs
Quick answers about time math.
Frequently asked questions
How do I add two time durations?
Use the “Add / Subtract durations” tab. Enter each duration in hours, minutes and seconds, keep the operation on + Add, and the result appears as h:mm:ss. Example: 2:30:00 + 1:45:30 = 4:15:30.
How do I subtract time durations?
Same tab — switch the operation to − Subtract. If the second duration is larger, the result shows a leading minus sign, e.g. 5:00:00 − 7:30:00 = −2:30:00.
What happens when the end time is earlier than the start time?
The calculator treats it as an overnight span: 24 hours are added to the end time. So 22:00 → 02:00 gives 4:00:00, covering the hours across midnight — the same convention shift planners and sleep trackers use.
What format does the result use?
Results show as h:mm:ss — hours unpadded, minutes and seconds zero-padded (e.g. 4:05:09). A leading − sign marks a negative duration. Totals in seconds, minutes, hours and days appear below the main result.
What if I leave a field empty?
Empty or non-numeric duration fields are treated as zero, so you can fill only the fields you need. In “Time difference” mode both clock times are required — you’ll see an error message until both are set.
Can I enter minutes or seconds above 59?
Yes. Because everything is converted to total seconds first, overflow normalizes automatically — 90 seconds behaves exactly like 1 minute 30 seconds.
How do I add days to a time duration?
Enter the days in the Days field of each duration — 1 day 2:00:00 plus 3:00:00 gives 29:00:00 (104,400 seconds). Days are just shorthand for 24-hour blocks: the calculator converts everything to seconds, adds, and converts back.
How do I add hours to a date?
Use the Date math tab: pick your start date and time, choose + Add duration, enter the days/hours/minutes/seconds, and the calculator returns the resulting date and time. For example, 2026-01-15 10:00 plus 36 hours gives 2026-01-16 22:00. The math is wall-clock — daylight-saving transitions are not adjusted.
What time expressions can the evaluator parse?
Suffixes d (days), h (hours), m (minutes) and s (seconds) with + and − operators, e.g. 1d 2h 3m 4s + 4h 5s – 2030s = 1d 5h 29m 19s (106,159 seconds). Spaces are optional, decimals work (1.5h), and invalid input shows an error instead of a wrong answer.
Is this time card calculator free?
Yes — this free time card calculator costs nothing, needs no sign-up, and stores nothing: every calculation runs in your browser. You can total a single shift or a whole week, deduct lunch, and read the result as decimal hours for payroll, all without an account.
How many hours is a typical shift after lunch is deducted?
A 9-hour span such as 8:00 AM to 5:00 PM with a 30-minute unpaid lunch is 8.5 paid hours. With a 60-minute lunch it is 8.0 hours, and an 8-hour span with a 30-minute lunch is 7.5 hours. The span itself never changes — only the unpaid break comes off.
How do I convert minutes to decimal hours for payroll?
Divide the minutes by 60. So 45 minutes is 0.75 hours, 20 minutes is 0.33 hours, and a 7:45 shift is 7.75 hours. The calculator does it for you: the Total hours figure under every result is already decimal, so 8:30 shows as 8.5.
What time will it be in 30 minutes?
Add 30 to the minutes and carry into the hours when you pass 60 — and flip AM to PM (or PM to AM) when you cross 12. From 12:45 PM it will be 1:15 PM; from 11:40 PM it will be 12:10 AM. The Date math tab works it out from any start time you enter.
How many hours are there in a week?
There are 168 hours in a week — 24 hours times 7 days. A standard 40-hour work week is just under a quarter of that (about 23.8%), and a 365-day year holds 8,760 hours. The conversions section above lists the matching minutes and seconds.
How do I calculate the hours between two times?
Convert both times to minutes since midnight, subtract, and if the answer is negative add 24 hours (1,440 minutes). From 9:47 AM to 6:25 PM is 1,105 − 587 = 518 minutes, which is 8 hours 38 minutes. Overnight works the same way: 10:15 PM to 6:45 AM is 8 hours 30 minutes. The Time difference tab does all of this automatically.
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Related guides
In-depth guides to hours worked, shifts and time cards.
Clock-in to clock-out, with breaks taken out.
Rounding rules and where every minute goes.
The shift pairs people ask about most, at a glance.
Future clock times from any starting point.
Weekly totals and where the overtime line falls.