Weight Loss Timeline Calculator

Eating a set number of calories a day? See roughly when you'd reach your goal weight, and how your loss slows down as you get lighter.

Your details

years
kg
Sex
cm
kg
kcal/day
Desk job plus training 2–4 times a week, or on your feet part of the day

Your results

Enter your details, goal weight and daily calories to see how long it takes.

How to use it

  1. Choose your units, then enter your sex, age, height and current weight.
  2. Enter your goal weight and the calories you plan to eat each day.
  3. Pick your activity level.
  4. Read your estimated goal date and the week-by-week table.

How it's calculated

Week by week. Unlike a simple “7,700 kcal = 1 kg” estimate, the calculator recalculates your maintenance calories every week as your weight drops:

  1. Maintenance (TDEE) = BMR from Mifflin-St Jeor × your activity level (FAO/WHO/UNU PAL: 1.40, 1.60, 1.85 or 2.20).
  2. Weekly loss = (maintenance − your intake) × 7 ÷ 7,700 kcal per kg (Hall, 2008).
  3. Your new weight goes into step 1 for the next week, until you reach your goal.

Your age is kept the same throughout. The goal date is today plus the number of weeks, and the table shows about ten rows across your plan.

Why it matters. The classic rule says a 3,500 kcal deficit (per pound) or 7,700 kcal (per kg) always gives the same loss. Thomas and colleagues (2013) showed that rule overestimates long-term loss, because energy needs fall as weight falls. Recalculating each week accounts for most of that.

Limits. The model doesn’t include adaptive thermogenesis, the extra drop in energy use some people see when dieting, or changes in water weight. The calculator withholds a forecast for goals below adult BMI 18.5, intakes below 1,250 kcal/day, starting deficits above 1,000 kcal/day or starting losses above 1% of bodyweight per week. The intake cutoff is a site limit above the range NICE reserves for supervised low-energy diets. Results flag an intake below estimated resting energy needs.

Sources

  1. Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 51(2), 241–247.
  2. FAO/WHO/UNU (2004). Human energy requirements: report of a Joint FAO/WHO/UNU Expert Consultation. FAO Food and Nutrition Technical Report Series 1. Table 5.3.
  3. Hall, K. D. (2008). What is the required energy deficit per unit weight loss? International Journal of Obesity, 32(3), 573–576.
  4. Thomas, D. M., Martin, C. K., Lettieri, S., Bredlau, C., Kaiser, K., Church, T., Bouchard, C., & Heymsfield, S. B. (2013). Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule. International Journal of Obesity, 37(12), 1611–1613.
  5. NICE. Overweight and obesity management (NG246). Low-energy and very-low-energy diets for adults.
  6. World Health Organization (2000). Obesity: preventing and managing the global epidemic. Technical Report Series 894. Adult BMI classification.
  7. Helms, E. R., Aragon, A. A., & Fitschen, P. J. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition, 11, 20.

Questions

Why does my weight loss slow down?

A lighter body burns fewer calories. If you keep eating the same amount, your daily deficit gets smaller every week, so you lose a little less each week. The table shows this happening.

Why does it say I'd level off before my goal?

The model can reach a point where maintenance drops to what you're eating. It also stops after 156 weeks, so a slower goal may fall beyond the forecast.

How accurate is the date?

Treat it as a rough guide. Your body also adapts to dieting in ways the equations don't capture, and day-to-day water changes hide progress. Real loss is often a bit slower than predicted.

How is this different from the Calorie Deficit Calculator?

That calculator starts from a deadline and tells you the deficit you need. This one starts from what you'll eat and tells you when you'd get there.

Updated November 9, 2026.