Weight Loss Calculator — Lose Weight on Your Schedule
Enter your current weight and goal weight, then set your timeline — by weeks or by weekly pace. This calculator shows your weekly loss rate, daily calorie deficit, calorie target, and estimated goal date. It can even work out your maintenance calories from your body stats.
Your plan
🔒 All calculations happen in your browser — no data leaves your device.
Your weight-loss plan
Your path to the goal
A straight-line projection at your weekly rate — redrawn live from your plan.
- The plan runs on one conversion: about 3,500 kcal per pound of body weight (7,700 per kilo), spread across your chosen weeks.
- At the defaults — 200 lb down to 180 lb over 20 weeks — that is 1.0 lb a week and a 500 kcal/day deficit, giving a 2,000 kcal/day target on 2,500 maintenance calories.
- Deficits above about 1,000 kcal a day are flagged as aggressive — most plans aim for 1–2 lb (0.5–1 kg) a week.
Enter your current weight and goal weight, then set your timeline — by weeks or by weekly pace. This calculator shows your weekly loss rate, daily calorie deficit, calorie target, and estimated goal date. It can even work out your maintenance calories from your body stats.
Keep exploring
Three companion tools for the full picture.
How it works
Three steps from where you are to where you want to be.
Enter current and goal weight
Type where you are and where you want to be. Toggle pounds or kilograms — the math follows.
Set your timeline
Choose how many weeks you have. The weekly loss rate and daily deficit appear instantly.
Read your targets
See your daily calorie deficit, calorie target (if you gave maintenance), and estimated goal date.
The math behind your plan
The plan is built on the energy-balance rule: one pound of body fat stores roughly 3,500 kcal (one kilogram ≈ 7,700 kcal). Lose weight at a steady rate, and the required daily deficit is:
Worked examples:
| Plan | Calculation | Result |
|---|---|---|
| 200 lb → 180 lb, 20 weeks | (20 ÷ 20) × 3,500 ÷ 7 | 1.0 lb/week · 500 kcal/day deficit |
| 90 kg → 80 kg, 20 weeks | (10 ÷ 20) × 7,700 ÷ 7 | 0.5 kg/week · 550 kcal/day deficit |
| 200 lb → 170 lb, 10 weeks | (30 ÷ 10) × 3,500 ÷ 7 | 3.0 lb/week · 1,500 kcal/day — too aggressive, flagged |
Go deeper
The details that separate a rough guess from a trustworthy plan.
A common, well-studied guideline is 1–2 lb (0.5–1 kg) per week:
- About 1 lb/week needs roughly a 500 kcal/day deficit — sustainable for most people.
- About 2 lb/week needs roughly a 1,000 kcal/day deficit — faster, but harder to sustain and easier to lose muscle.
- Faster than that raises the risk of muscle loss, fatigue, nutrient gaps, and regain — this calculator flags it in red.
Early drops are often water weight, not fat — judge the plan over weeks, not days.
- Metabolic adaptation — your body burns fewer calories as you get lighter, so real loss slows even at a fixed deficit.
- Muscle vs. fat — protein intake and resistance training decide how much of the loss is fat.
- Maintenance accuracy — the optional daily target is only as good as your maintenance estimate.
- Plateaus — weeks with no scale movement are normal; consistency beats any calculator.
This is a planning estimate, not medical advice — talk to a healthcare professional before a big deficit.
Frequently asked questions
Quick answers about this weight loss calculator.
How does this weight loss calculator work?
Enter your current weight, goal weight, and weeks. It divides the total loss by the weeks for your weekly rate, then converts that to a daily calorie deficit using 3,500 kcal per pound (7,700 per kg), and estimates your goal date. You can also pick a weekly pace instead of typing weeks, and let the calculator derive your maintenance calories from your body stats.
How fast can I safely lose weight?
A widely used guideline is 1–2 lb (0.5–1 kg) per week. This calculator flags plans above about 2 lb/week or a 1,000 kcal/day deficit as aggressive — faster plans risk muscle loss, fatigue, and rebound.
What is a calorie deficit and how big should it be?
A deficit is eating fewer calories than you burn. About 500 kcal/day loses roughly 1 lb per week; about 1,000 kcal/day loses roughly 2 lb per week. Bigger deficits are harder to sustain — see the pace check above.
Does this work with kilograms?
Yes — toggle kg above the inputs. The math switches to 7,700 kcal per kilogram, so 0.5 kg/week needs about a 550 kcal/day deficit.
What if my goal weight is higher than my current weight?
The calculator shows an error — it is a weight-loss planner. For gaining, keep a small surplus instead, and the calorie and macro calculators can help you plan meals.
Is a 500 kcal deficit right for everyone?
No — it is a useful default, not a prescription. Your real maintenance calories depend on size, activity, and age. This tool gives estimates for planning; it is not medical advice.
Can the calculator work out my maintenance calories?
Yes — under Daily maintenance calories choose “Work it out for me” and add your sex, age, height and activity level. It estimates your BMR with the Mifflin-St Jeor equation — or Revised Harris-Benedict, or Katch-McArdle if you know your body fat % — and multiplies by your activity level: the same math as our TDEE calculator. The figure is filled into the maintenance field, so the plan runs on it exactly as if you had typed it.
What is a zigzag (calorie-cycling) schedule?
A zigzag week spreads the same weekly calories unevenly instead of eating the same target every day: three higher days and four lower days around your daily target. This calculator uses +200 kcal on the higher days (Mon, Wed, Fri) and −150 kcal on the lower days, so the weekly average lands exactly on your target — the same convention as our Calorie Calculator.
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More ways to plan food, activity, and body metrics.
Disclaimer
This calculator provides estimates for information only — it is not medical, nutrition, or fitness advice. Calorie needs, metabolism, and safe loss rates vary by person. Do not attempt large deficits without guidance; consult a healthcare professional or registered dietitian before starting a weight-loss plan.