Weight Loss Timeline Calculator — When Will You Reach Your Goal?
See the date you would reach your goal weight at a weekly pace, a % of body weight, a deadline or a daily deficit — with a week-by-week plan, a weight chart, safe-pace checks and your maintenance calories at goal.
How it works
Weeks = (current − goal) ÷ weekly loss · % plan: weeks = ln(goal ÷ current) ÷ ln(1 − weekly %) · Daily deficit = weekly loss × 3,500 kcal per lb (7,716 per kg) ÷ 7 · Maintenance = Mifflin-St Jeor BMR × activity factor · Goal date = start date + weeks × 7 days
Choose how you want to plan: a fixed weekly pace, a percentage of your body weight each week (the pace shrinks as you get lighter, closer to how weight loss really behaves), a deadline in weeks, or a daily calorie deficit. The calculator turns that into the number of weeks and the calendar date you would reach your goal, using the standard approximation that a pound of body fat stores about 3,500 kcal (about 7,700 kcal per kilogram). It also estimates your maintenance calories with the Mifflin-St Jeor equation and your activity level, both today and at your goal weight, so you can see how much to eat to stay on pace each week and how much to eat afterwards to keep the weight off. The pace is checked against common safety guidance: about 0.5–1% of body weight or up to 1–2 lb (0.5–0.9 kg) a week, and a daily intake no lower than 1,200 kcal for women or 1,500 kcal for men without medical supervision. If your plan would need less, it shows the later goal date you can reach at a safe intake. The chart also shows what happens if you keep eating your starting calories: loss slows as maintenance falls and can level off before the goal.
Worked example
A 35-year-old woman, 5′5″ and lightly active, wants to go from 180 lb to 160 lb at 1 lb a week. That is 20 lb, so 20 weeks (about 4.6 months). One pound a week needs 3,500 ÷ 7 = 500 kcal a day below maintenance. Her estimated maintenance is about 2,079 kcal now, so she eats about 1,579 kcal at the start and about 1,455 kcal near the end, as maintenance falls to about 1,955 kcal at 160 lb. Once she reaches 160 lb, about 1,955 kcal a day holds that weight. One pound a week is 0.56% of her body weight, inside the usual safe range.
Sources: NIDDK — Body Weight Planner · CDC — Losing weight · Mifflin MD et al. (1990) — A new predictive equation for resting energy expenditure · Hall KD et al. (2011) — Quantification of the effect of energy imbalance on bodyweight
Frequently asked questions
How long will it take to lose 20 pounds?
At 1 lb a week, about 20 weeks; at 0.5 lb a week, about 40; at 2 lb a week, about 10. The calculator gives the exact date from your start day and compares four paces side by side, flagging any that would need fewer calories than the usual safe minimum.
What is a safe rate of weight loss?
Most health bodies suggest about 0.5–1% of body weight a week, which is roughly 1–2 lb (0.5–0.9 kg) for most adults, and an intake no lower than about 1,200 kcal a day for women or 1,500 for men unless a doctor supervises. The Pace check result and the notes tell you where your plan sits.
Why does the plan lower my calories each week?
A lighter body burns less energy, so your maintenance calories fall as you lose weight. To keep losing at the same pace, intake has to drift down too. The week-by-week table shows both numbers, and the chart shows how loss slows if you keep eating your starting amount instead.
What are maintenance calories at goal?
They are the calories that hold your new weight steady once you get there, estimated with the Mifflin-St Jeor equation at your goal weight and your activity level. Eating around that amount after the diet is what keeps the weight off.
Does the goal date assume a constant rate?
With a weekly pace, deadline or daily deficit, yes — the same loss every week. Choose "% per week" for a pace that shrinks as you get lighter, which is closer to real life. Either way, treat the date as an estimate: water, sodium and hormones move the scale day to day.
Can the deficit come from exercise instead of eating less?
Yes. The deficit is the gap between what you burn and what you eat, so extra activity counts. If your plan would need fewer calories than the safe minimum, adding activity is the way to keep the pace.
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Educational estimate using standard published formulas — not medical, dietary or nutritional advice. Individual needs vary with health status, medication and activity; consult a qualified clinician or dietitian before making changes.