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Weight Loss Calculator
See how long it would take to reach a goal weight at a daily calorie deficit you choose, and the date that lands on. The calculator estimates your maintenance calories with the Mifflin-St Jeor equation and applies the rough rule that a pound of body weight is worth about 3,500 kcal.
- Estimated goal date
- Sun, Jan 24, 2027
- Daily calorie intake
- 2,263 kcal/day
- Maintenance calories (TDEE)
- 2,763 kcal/day
- Loss per week
- 1 lb
- Check
- Intake stays above the commonly cited minimum
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Enter your sex, age, height, current weight and activity level.
- Enter your goal weight.
- Enter the daily calorie deficit you plan to keep and a start date.
- Read the number of weeks, the estimated date and the daily intake that deficit implies.
Worked examples
A moderately active 30-year-old man going from 180 lb to 165 lb at a 500 kcal daily deficit from Jan 1, 2026
- Time to reach your goal
- 15 weeks
- Estimated goal date
- Thu, Apr 16, 2026
- Daily calorie intake
- 2,263 kcal/day
- Maintenance calories (TDEE)
- 2,763 kcal/day
- Loss per week
- 1 lb
A sedentary 35-year-old woman (165 cm, 65 kg) asking for a 500 kcal deficit — refused because 1,614 − 500 is under 1,200
- Maintenance calories (TDEE)
- 1,614 kcal/day
- Check
- Not calculated: this deficit would put intake below 1,200 kcal a day. Choose a smaller deficit.
A rough rule
The 3,500 kcal per pound figure is a long-standing approximation, not a law. It predicts a straight line, but real weight loss curves flatten: a lighter body burns fewer calories, so the same intake produces a smaller deficit as you go. Expect the later weeks to be slower than the estimate, and recalculate as your weight changes.
When the calculator will not give an answer
If the deficit you enter would put your daily intake below 1,200 kcal for women or 1,500 kcal for men, no timeline is shown. Those are the levels commonly cited as the lowest that should be followed without medical supervision. Choose a smaller deficit, or raise your activity so that maintenance is higher.
A loss of 1 to 2 lb (0.5 to 1 kg) a week — a deficit of roughly 500 to 1,000 kcal a day — is the pace generally advised.
This is an estimate for general information, not medical advice. Talk to a doctor or other qualified clinician before making health decisions based on it.
Questions people ask
How long does it take to lose 15 pounds?
At a 500 kcal daily deficit, about 15 weeks: 15 lb × 3,500 = 52,500 kcal, divided by 500 a day is 105 days. At 750 kcal a day it is about 10 weeks.
How much weight will I lose with a 500 calorie deficit?
Roughly 1 lb (0.45 kg) a week by the 3,500 kcal rule, usually a little less over the long run as your body adapts.
Why does the calculator show no result for my deficit?
Because the intake left after the deficit would be under 1,200 kcal (women) or 1,500 kcal (men) a day. For example, a maintenance level of 1,614 kcal minus 500 leaves 1,114, so nothing is calculated; a 300 kcal deficit would work.