Speed Calculator – Speed, Distance or Time From the Other Two
Give it any two of speed, distance and time and it finds the third.
What do you want to find?
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Advanced options — pace, knots and feet per second for any run or trip
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The pace, knots and feet-per-second figures below are worked out from the Advanced panel’s own distance and time — open Advanced options to use them alongside the main calculator.
Pace, knots and feet per second for any run or trip are already included in the result with their default values — open Advanced options to change them.
Your speed
The same journey, every way you might need it
What this speed feels like
5 mph is a brisk walk tipping towards a jog — a mile every 12:00. Keep it up for an hour and you have covered serious ground on foot.
Average, honestly: every answer here is an average over the whole journey — stops, slow patches and fast stretches all folded in. A speedometer shows the speed of the moment; a trip computer, like this page, shows the average that decides when you actually arrive.
Covered 10 miles in 2 hours? That is 5 mph — 8.05 km/h — at a 12:00-per-mile pace, and this page shows all of it at once. Give it any two of speed, distance and time and it finds the third, in miles, kilometres or metres, with your pace per mile and per kilometre alongside, because runners think in pace and drivers think in speed and both deserve the same answer.
Key takeaways
- Give the calculator any two of speed, distance and time and it finds the third, in miles, kilometres or metres at once.
- Runners think in pace and drivers think in speed: pace is minutes per mile or per kilometre, and this page shows both beside every speed.
- Average speed is total distance divided by total time, never the average of two speeds.
Your speed on the dial
The needle sits where your average speed falls on a dial that tops out at 120 mph — the range of an ordinary road car. Walking pace hugs the left; motorway speeds sweep to the right.
5 mph on a 120 mph dial — on foot, right at the gentle end.
Why the dial stops at 120 mph
Everyday speeds live between a 3 mph stroll and a 70 mph motorway cruise, so the dial is scaled to ordinary roads — a needle you can actually read. Enter something far faster, like a plane at 550 mph, and the needle simply parks at the end of the dial while the numbers above stay exact. The picture is a guide; the figures are the answer.
How it works, in 3 steps
Pick the corner you are missing
Speed, distance or time — tap the tab for the one you want. The page asks only for the other two, so there is never a box you do not need.
Enter the two you know, in your units
Miles, kilometres or metres for distance; hours, minutes and seconds for time — fill only the time boxes you have. A 45-minute trip is 0 hours, 45 minutes, 0 seconds.
Read the answer in every unit at once
Speed arrives as mph, km/h and m/s together, with pace per mile and per kilometre — no second conversion, no mental arithmetic, whichever tribe you belong to.
The arithmetic behind it
The default, worked through. 10 miles in 2 hours: 10 ÷ 2 = 5 mph. The conversions are exact factors, not estimates: 5 × 1.609344 = 8.04672, shown as 8.05 km/h, and 8.04672 ÷ 3.6 = 2.24 m/s. Pace turns the same numbers upside down: 120 minutes spread over 10 miles is 12:00 per mile; over 10 × 1.609344 = 16.09 kilometres it is 7:27 per kilometre.
The drive. 60 km in 45 minutes is 60 ÷ 0.75 = 80 km/h — and 80 ÷ 1.609344 = 49.71 mph, which is why a continental speedo reading of 80 feels calmer than it looks to a visitor from a miles country. In metres per second it is 80 ÷ 3.6 = 22.22 m/s.
The 100 metres. A 9.58-second 100 m works out to 100 ÷ 9.58 = 10.44 m/s. Multiply by 3.6 for 37.58 km/h — the fastest a human has ever averaged over the distance, start from blocks included. Sprint speeds are quoted in m/s because a race is over before an hour-based unit has time to mean anything.
Deep dives
Drive out at 60 mph and home at 30 mph and your average is not 45 — it is 40. Say the trip is 30 miles each way. Out takes 30 minutes; back takes a full hour. Total: 60 miles in 90 minutes, and 60 ÷ 1.5 = 40 mph. The slow leg drags the average down because you spend twice as long in it — averages over distance weight every speed by the time spent travelling at it, not by the miles covered.
This is why the honest way to average is always total distance ÷ total time — the only formula this page uses. It is also why a journey that feels “mostly motorway” still produces a modest average: the last two miles through town at 15 mph can cost as many minutes as twenty miles of cruising. Navigation apps keep arriving later than their first estimate for exactly this reason — the slow tail of a trip is longer, in minutes, than it looks on the map.
Each surviving unit belongs to a world that refuses to give it up. Miles per hour rules the roads of the US and UK, where the mile — fixed at 1,760 yards in 1593 and at exactly 1.609344 kilometres by international agreement in 1959 — is printed on every sign. Kilometres per hour covers almost everywhere else, riding on the metre. And metres per second, the SI unit, owns science: physics, weather (wind speeds), and sprinting, where a race lasts seconds and an hour-based unit would shrink every number towards zero.
The good news is that the bridges between them are exact. mph to km/h is multiply by 1.609344; km/h to m/s is divide by 3.6; m/s to km/h is multiply by 3.6. Nothing on this page is estimated — a speed carried across all three units and back returns to exactly where it started, which is more than can be said for the rough “times 1.6” rule of thumb drivers use at ferry ports.
Pace, splits and race-day arithmetic
The main calculator already shows pace beside every speed, because runners plan in pace and drivers plan in speed, and the two are reciprocals of each other: pace is time divided by distance, speed is distance divided by time. The default trip, 10 miles in 2 hours, is 5 mph and a 12:00-per-mile pace, or 7:27 per kilometre. The Advanced options panel above works out pace for any distance and time you enter, including knots and feet per second, so a runner and a sailor can use the same page.
Splits are where pace becomes a plan. A marathon run at a perfectly even pace has a fixed time at every marker, and the table below shows the markers for a 4-hour marathon on the calculator’s 26.2-mile distance. The displayed pace is 9:10 per mile, and the splits are worked from the unrounded pace of 240 minutes divided by 26.2 miles, which is why the markers add up to exactly 4:00:00 while the rounded pace would overshoot by a few seconds. That rounding gap is a useful warning: a pace rounded to the second, held for four hours, drifts by seconds, and a pace rounded to the minute drifts by minutes.
| Marker | Distance | Split time at even pace |
|---|---|---|
| 5 km | 3.11 miles | 28:28 |
| 10 km | 6.21 miles | 56:55 |
| Half marathon | 13.11 miles | 2:00:05 |
| 20 miles | 20.00 miles | 3:03:12 |
| Finish | 26.20 miles | 4:00:00 |
Two shorter races make the same point more sharply. A 5 km run in 25 minutes is an 8:03-per-mile pace and exactly 5:00 per kilometre, and a 10 km run in 50 minutes is the same pace in both units, because doubling both distance and time leaves pace unchanged. That invariance is why pace is the better planning number for runners: a 5:00-per-kilometre runner knows the 10 km time without any new arithmetic, while a speed in miles per hour has to be converted twice. For the same reason, the calculator shows pace per mile and per kilometre together: the audience that thinks in miles and the audience that thinks in kilometres are looking at one run, not two.
Real races are rarely even-paced, and the split table is a baseline to deviate from, not a promise. Most runners slow in the second half, so a common plan is to bank a small margin early: aim for the half-marathon marker a minute or two ahead of even pace, and treat the 20-mile marker as the honest checkpoint, because the last 10 km of a marathon is where even pace usually breaks. If the 20-mile split is already behind schedule, the finish time follows the second-half pace, not the plan, and no amount of arithmetic in the last miles recovers a gap that took twenty miles to open.
Speed in mph, km/h, m/s, knots and ft/s
The main calculator shows miles per hour, kilometres per hour and metres per second together, because those three cover roads, science and most of daily life. Two more units belong in the picture: knots, used in aviation and sailing, and feet per second, used in physics and ballistics. The Advanced options panel converts any pace-panel trip into both, and the table below gives the conversions for round speeds so a forecast, a speedometer or a textbook figure can be read in any unit.
| mph | km/h | m/s | knots | ft/s |
|---|---|---|---|---|
| 5 | 8.05 | 2.24 | 4.34 | 7.33 |
| 10 | 16.09 | 4.47 | 8.69 | 14.67 |
| 30 | 48.28 | 13.41 | 26.07 | 44.00 |
| 60 | 96.56 | 26.82 | 52.14 | 88.00 |
The exact factors are: 1 mph = 1.609344 km/h, exactly, because the international mile is defined as 1,609.344 metres; 1 mph = 0.44704 m/s, from the same definition; 1 mph = 0.868976 knots, because a knot is one nautical mile per hour and a nautical mile is defined as exactly 1,852 metres; and 1 mph = 1.46667 ft/s, because a mile is 5,280 feet and an hour is 3,600 seconds. The knots factor is the one most often misremembered, usually as 0.87, which is close enough for a glance and wrong enough to matter over a long passage: over 100 nautical miles, the rounding costs more than a mile. The calculator’s own default makes the point concretely: 5 mph is 8.05 km/h and 2.24 m/s, and in the Advanced panel the same trip is 4.34 knots and 7.33 ft/s.
Time entry deserves a note of its own, because it is where speed calculators most often go wrong. This calculator takes hours, minutes and seconds separately, so 40 minutes is entered as 0 hours and 40 minutes, not as 0.40 hours, and 1 hour 30 minutes is 1.5 hours, not 1.30 hours. The classic error is entering 90 minutes as 1.90 hours and wondering why the speed looks slow; the separate fields exist to prevent exactly that slip. If a time arrives as a decimal, convert it first: the minutes are the decimal part times 60, so 2.75 hours is 2 hours and 45 minutes.
Multi-leg trips: why average speed is not the average of speeds
A trip with more than one leg is where the simple speed formula quietly breaks if it is applied leg by leg and then averaged. The correct rule is unchanged: average speed is total distance divided by total time. The trap is averaging the leg speeds instead, which weights every leg equally even when the legs take very different times. The table below is a three-leg trip that makes the trap visible.
| Leg | Distance | Time | Leg speed |
|---|---|---|---|
| City streets | 30 miles | 0.5 hours | 60 mph |
| Motorway | 60 miles | 1.5 hours | 40 mph |
| Country lanes | 20 miles | 1.0 hours | 20 mph |
| Whole trip | 110 miles | 3.0 hours | 36.67 mph |
The average of the three leg speeds is 40 mph, but the trip’s average speed is 36.67 mph, because the slow leg takes a full hour while the fast leg takes only half an hour. The time-weighted answer is the one that predicts arrival: 110 miles at 36.67 mph takes 3 hours, while 110 miles at the naive 40 mph would predict 2 hours 45 minutes, fifteen minutes early. The same effect in its purest form is two 60-mile legs, one at 60 mph and one at 30 mph: the times are 1 hour and 2 hours, the total is 120 miles in 3 hours, and the average is 40 mph, not the 45 mph that a straight average of the speeds suggests. Whenever a journey mixes fast and slow sections, the slow sections dominate the average, because they consume the time.
Segment speeds still matter, just for a different question. The leg speeds tell you where the journey felt fast or slow, which sections to improve, and whether a route change helps; the overall average tells you when you arrive. A route that replaces the slow country leg with a longer but faster motorway leg can raise the average even while adding miles, because it trades distance for time, and that trade is exactly what the total-distance-over-total-time rule evaluates. Work each leg with the main calculator, add the distances and the times separately, and divide once at the end: that single division is the whole method, and every shortcut around it is an approximation that fails precisely when the legs differ most.
Speed in everyday problems
Most speed problems outside a classroom are arrival-time problems, and they all reduce to the same division, with one extra step: stops and delays count as time but add no distance, so they drag the average down. A 120-mile drive at a steady 60 mph takes exactly 2 hours, but add a single 20-minute fuel stop and the trip becomes 120 miles in 2 hours 20 minutes, an average of 51.4 mph, not 60. The stop did not slow the car; it lengthened the time, and average speed answers for the whole trip, stops included. Anyone who promises arrival from cruising speed alone is quietly deleting the stops.
Walking and cycling reward the pace form of the same arithmetic. A walker at 20 minutes per mile covers 3 miles in exactly an hour, because pace multiplied by distance is time: 3 times 20 minutes is 60 minutes. The same walker in speed terms moves at 3 mph, and 3 miles divided by 3 mph is again 1 hour; the two forms agree because they are the same division seen from opposite sides. A cyclist at 15 mph covers 15 miles in an hour, while at 12 mph the same ride takes 1 hour 15 minutes, since 15 divided by 12 is 1.25 hours. The practical habit is to convert the awkward unit before dividing: if the ride is 45 minutes, write it as 0.75 hours, and the division stays clean.
Longer journeys add a unit trap. A train covering 200 miles in 2 hours 30 minutes averages 80 mph, because 2 hours 30 minutes is 2.5 hours and 200 divided by 2.5 is 80. A short flight of 500 miles at 250 knots needs a conversion first: 250 knots is 287.7 mph, since a knot is 0.868976 mph in reverse, and 500 divided by 287.7 is 1.74 hours, or about 1 hour 44 minutes of flying time, before taxi, climb and descent are counted. Speed limits add the same trap in the other direction: 100 km/h is 62.1 mph, and 30 mph is 48.3 km/h, so a driver crossing between metric and imperial speedometers who reads the number without converting is off by more than half.
Three mental shortcuts cover most everyday estimates without a calculator. At 60 mph you cover a mile a minute, so minutes and miles are the same number. At 30 mph you cover a mile every two minutes, so double the miles for the minutes. And 10 km/h is exactly 6 minutes per kilometre, so a 5 km run at 10 km/h takes 30 minutes. Each shortcut is just the speed formula with round numbers chosen so the division disappears, and each one can be checked against the calculator above in seconds. When the numbers stop being round, use the calculator: the shortcuts are for estimating, and an arrival time promised to someone else deserves the exact division.
Speed units at a glance: the conversions you will actually use
Speed is distance divided by time, and the units follow the quantities: kilometres per hour, miles per hour, metres per second, knots, and feet per second are all the same idea with different scales. The conversions worth memorising are 1 mile per hour = 1.60934 kilometres per hour, 1 metre per second = 3.6 kilometres per hour, and 1 knot = 1.852 kilometres per hour (one nautical mile per hour). A speed of 60 mph is therefore 96.6 km/h; 10 metres per second is 36 km/h, or 22.4 mph; and 20 knots is 37.0 km/h.
The conversion that causes the most real-world confusion is metres per second to kilometres per hour in weather and sport reporting: multiply by 3.6, never by 3 or 4. And remember that average speed is total distance divided by total time, including stops — a journey of 120 miles in 2 hours 30 minutes averages 48 mph even if the speedometer spent most of the trip at 70, because the stops and slow stretches count in the denominator.
Instantaneous speed, average speed, and velocity: three different answers
Three quantities share the word speed in everyday speech, and physics keeps them apart. Instantaneous speed is the speedometer reading at one moment. Average speed is total distance divided by total time for a whole journey. Velocity adds direction: it is displacement (straight-line distance from start to finish, with direction) divided by time, so a round trip that returns to its start has an average velocity of zero however fast it was driven. The calculator on this page computes average speed from distance and time; it does not need direction, and it does not report velocity unless the journey is a straight line, in which case the two coincide in magnitude.
The distinction matters whenever direction changes. A runner who completes a 400-metre lap in 60 seconds averages 6.67 metres per second in speed, but zero in velocity, because the displacement is zero. A car that drives 30 miles east and 30 miles west in two hours averages 30 mph in speed and 0 mph in velocity. If a problem asks for velocity, it wants the displacement version; if it asks how fast, on average, the journey was, it wants the distance version.
Speed questions, answered
How do I calculate speed from distance and time?
Divide the distance by the time, keeping the units matched: 10 miles in 2 hours is 10 divided by 2 = 5 mph. If the time is in minutes, either convert it to hours first (45 minutes is 0.75 hours) or let this page do it — it takes hours, minutes and seconds separately. The answer is always an average over the whole journey, stops included if they were inside the time you entered.
How do I convert mph to km/h?
Multiply by 1.609344 — the exact length of a mile in kilometres. 60 mph is 96.56 km/h, and 5 mph is 8.05 km/h. To go the other way, divide: 100 km/h is 62.14 mph. For a rough roadside estimate, multiplying mph by 1.6 is close enough, but the figures on this page use the exact factor, so nothing drifts over a long journey.
What is the difference between speed and pace?
Speed says how much distance you cover in an hour; pace says how many minutes one mile or kilometre takes. They are the same performance read from opposite ends: 6 mph is a 10:00-per-mile pace, and a 5:00-per-kilometre pace is 12 km/h — about 7.46 mph. Runners plan races in pace because each split is one unit of distance; drivers plan trips in speed because the signs and limits use it.
How long will 100 miles take at 60 mph?
100 divided by 60 = 1.667 hours — 1 hour 40 minutes of pure driving. Use the Time tab above: distance 100 miles, speed 60 mph. Real journeys take longer once fuel stops, traffic and slower roads join in, which is why trip planners usually work with an average nearer 45 to 50 mph for a mixed route than the 60 on the motorway signs.
Why is my average speed lower than my top speed?
Because an average folds everything in: the minutes at lights, the slow climb, the crawl behind a lorry. Even a journey spent mostly at 60 mph averages far less once the first and last miles on small roads join in — 30 miles with 20 at 60 mph and 10 at 20 mph takes 20 + 30 = 50 minutes, an average of just 36 mph. The average is the figure that decides your arrival time, so it is the one worth planning with.
What does m/s mean, and where is it used?
Metres per second — how many metres you cross in one second. Multiply by 3.6 to get km/h, so 10 m/s is 36 km/h. It is the standard unit in physics and the one sprinting uses: a 9.58-second 100 m averages 10.44 m/s. It suits short, fast events because the numbers stay readable — walking is about 1.4 m/s, a sprinter peaks near 12 m/s, and a motorway car cruises at roughly 31 m/s.
How do I pace a marathon from a target finish time?
Divide the target time by the distance: a 4-hour marathon over 26.2 miles needs 240 ÷ 26.2 = 9.16 minutes per mile, displayed as about 9:10 per mile, or 5:42 per kilometre. The splits table on this page shows the marker times for that pace (5 km in 28:28, half marathon in 2:00:05, 20 miles in 3:03:12), and the Advanced options panel works out the pace for any distance and time you enter.
What is a knot, and where is it used?
A knot is one nautical mile per hour, and a nautical mile is defined as exactly 1,852 metres, so 1 mph = 0.868976 knots. Knots are the standard speed unit in aviation and sailing, which is why forecasts for sea and air quote wind and vessel speed in knots rather than miles or kilometres per hour. The Advanced options panel converts any trip into knots.
Why is my trip’s average speed lower than the average of my leg speeds?
Because average speed is total distance divided by total time, and slow legs consume more time than fast legs. Two 60-mile legs at 60 mph and 30 mph take 1 hour and 2 hours, so the average is 120 miles ÷ 3 hours = 40 mph, not 45 mph. The multi-leg table on this page works a three-leg trip through the same point.
When should I use feet per second instead of mph?
Feet per second is the natural unit in physics and engineering problems, where distances are in feet and times in seconds: projectile motion, falling objects, and conveyor or fluid speeds are all usually stated in ft/s. The conversion is 1 mph = 1.46667 ft/s, so 60 mph is 88 ft/s, and the Advanced options panel shows ft/s for any trip.
What is the formula for average speed?
Average speed = total distance ÷ total time. Use consistent units: distance in kilometres and time in hours gives km/h; distance in miles and time in hours gives mph. Include all time, including stops, in the denominator — otherwise the result is a moving average, not the journey average.
How do I convert mph to km/h?
Multiply by 1.60934. 60 mph × 1.60934 = 96.6 km/h. To convert km/h to mph, divide by 1.60934 (or multiply by 0.621371): 100 km/h = 62.1 mph.
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→Exact arithmetic — averages, not promises.
Every figure on this page is an exact average from the numbers you enter, using 1 mile = 1.609344 km exactly. An average is not a forecast: real travel times depend on traffic, weather, stops and the roads themselves, and no result here should be used for navigation, safety decisions or beating a deadline you cannot afford to miss. Speed limits are legal maximums, not target averages — plan with a realistic average and arrive unhurried.