Weight loss calculator.
See how long your weight loss will take. Enter your current and goal weight and a daily calorie deficit, and the calculator estimates the weeks and a target date.
Your goal
LiveBased on about 3,500 calories per pound. A 500 calorie daily deficit is roughly a pound a week. Aim for 0.5 to 2 lb a week for steady loss.
Time to goal
20 weeks
to reach 160 lb
An estimate; the 3,500-calorie rule simplifies real fat loss, which slows over time. Not medical advice. Calculations run in your browser; nothing is stored.
How it works
Deficit, time and date
Weight loss comes down to a calorie deficit over time. Because a pound of fat is about 3,500 calories, the calculator works out the total calories between your current and goal weight, then divides by your daily deficit to estimate the days, weeks and a target date.
Losing 20 lb on a 500 calorie daily deficit takes about 140 days, or 20 weeks, at roughly a pound a week. A larger deficit is faster but harder to sustain.
Reference
Daily deficit to weekly loss.
How a daily calorie deficit translates into weekly weight loss, using 3,500 calories per pound.
| Daily deficit | Weekly loss |
|---|---|
| 250 cal | 0.5 lb |
| 500 cal | 1.0 lb |
| 750 cal | 1.5 lb |
| 1,000 cal | 2.0 lb |
The full guide
The complete guide to weight loss timing.
How the timeline works, how to pick a safe pace, and why real loss is rarely a straight line.
How the timeline works
The estimate uses the rule that a pound of fat holds about 3,500 calories. Multiply the pounds you want to lose by 3,500 to get the total calories, then divide by your daily deficit to find the days it should take.
A 500 calorie deficit clears about a pound a week, so the time to goal is roughly the pounds to lose in weeks.
Choosing a safe pace
Aiming for 0.5 to 2 lb a week is sustainable for most people. Faster than that usually means a very large deficit that is hard to hold and can cost muscle. Do not drop daily calories below roughly 1,200 for women or 1,500 for men.
A slower pace is easier to live with and more likely to stick, which matters more than speed.
Why loss is not a straight line
Real weight loss wobbles. Water, glycogen, hormones and the scale itself move day to day, and as you get lighter your maintenance falls, so the same deficit slows over time. The 3,500 rule tends to be optimistic over long periods.
Judge progress over several weeks and recalculate as your weight drops.
Making the plan work
Find your maintenance with a TDEE calculator, set a deficit you can keep, and prioritise protein and strength work to hold muscle. Track honestly, since most people underestimate intake.
Use the target date as motivation, not a deadline, and adjust the deficit if progress stalls for a few weeks.
The formula
Pounds over
deficit.
Total calories to lose is pounds times 3,500. Divide by your daily deficit to get the days.
Find your maintenance ›# Time to goal
total_cal = (current − goal) × 3500
days = total_cal / daily_deficit
# worked example
20 lb × 3500 / 500 = 140 days (20 wk)Questions
Weight loss questions.
How long will it take to lose weight?
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It depends on how much you want to lose and your daily deficit. Losing 20 lb on a 500 calorie deficit takes about 20 weeks, at roughly a pound a week. Enter your numbers above.
How do I calculate weight loss time?
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Multiply the pounds to lose by 3,500 for the total calories, then divide by your daily deficit to get the days. A larger deficit shortens the time but is harder to sustain.
What is a safe rate of weight loss?
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About 0.5 to 2 lb a week. Faster usually needs a very large deficit that is hard to keep and can cost muscle. Do not go below roughly 1,200 calories for women or 1,500 for men.
Why is my real loss slower than the estimate?
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The 3,500-calorie rule is a simplification. Water and hormones swing the scale, and your maintenance falls as you lose weight, so the same deficit slows down. Judge progress over weeks.
Is this weight loss calculator free?
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Yes. It is completely free with no sign-up, and every calculation runs locally in your browser, so nothing you enter is stored or sent anywhere.
About the developer
Jean Borg
Jean builds and maintains every calculator on freecalculators.pro from Malta, with a focus on tools that are fast, free and show their working. The weight loss calculator uses the standard 3,500-calorie estimate and is for general information, not medical advice.