Weight Loss Calculator

See how long it may take to reach your goal weight and how many calories a day that plan requires.

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How to use the Weight Loss Calculator

  1. Choose the sex.
  2. Enter the age.
  3. Choose the units.
  4. Enter the height – feet.
  5. Enter the height – inches.
  6. Enter the height.
  7. Enter the current weight.
  8. Enter the current weight.
  9. Enter the goal weight.
  10. Enter the goal weight.
  11. Choose the activity level.
  12. Choose the rate of loss.
  13. Pick the start date.
  14. Press Calculate. The result updates automatically as you type.

About the Weight Loss Calculator

A goal date makes a weight-loss plan concrete. This calculator estimates your current maintenance calories, subtracts the deficit needed for your chosen weekly rate, and projects when you would reach your goal if you kept it up.

For most people, losing 0.5–1% of body weight per week (about 1–2 lb for a 200 lb person) is a sustainable pace that preserves muscle, especially combined with strength training and enough protein. Expect week-to-week fluctuations from water and food volume, and judge progress by the trend over several weeks. Plateaus are normal; recalculate as your weight changes.

Results are estimates for general information only and are not medical advice. Talk to a doctor or registered dietitian before making major changes.

Formula

TDEE = Mifflin-St Jeor BMR × activity factor
Daily deficit = rate (lb/week) × 3,500 ÷ 7 = rate × 500 kcal
Weeks to goal = (current − goal weight in lb) ÷ rate

The 3,500 kcal-per-pound rule (about 7,700 kcal per kg) is an approximation. It assumes your maintenance needs stay constant, so real progress usually slows over time.

Example calculation

Using the default values:

  • Sex = Male
  • Age = 35 years
  • Units = US (ft, in, lb)
  • Height – feet = 5 ft
  • Height – inches = 10 in
  • Current weight = 200 lb
  • Goal weight = 180 lb
  • Activity level = Moderately active (exercise 3–5 days/week)
  • Rate of loss = 1 lb (0.45 kg) per week
  • Start date = 2026-09-01

the calculator returns:

  • Estimated goal date: Tuesday, January 19, 2027
  • Time needed: 20 weeks
  • Daily calories to eat: 2,365 kcal/day
  • Current maintenance (TDEE): 2,865 kcal/day
  • BMI at goal weight: 25.8

Frequently asked questions

How fast can I safely lose weight?

Around 1–2 lb (0.5–0.9 kg) per week is widely recommended for adults. Faster loss is possible early on, mostly from water, but is harder to sustain.

Why does weight loss slow down?

As you lose weight your body needs fewer calories, and metabolism adapts a little, so the same intake creates a smaller deficit. Recalculating periodically keeps the plan accurate.

Should I exercise or just eat less?

Both help. Diet creates most of the deficit, while exercise, especially strength training, helps keep muscle and makes the weight easier to maintain.

Last updated: · Category: Health & Fitness calculators

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