Weight Loss Timeline Calculator

Enter where you are, where you want to be and what you plan to eat. The projection recalculates your TDEE for every day, so the date reflects the slowdown that comes with a lighter body.

Example: a 35-year-old woman going from 180.0 lb to 160.0 lb on 1,579 kcal a day. Enter your numbers to replace it.

Example goal date

April 10, 2027

About 23.0 weeks (161 days) from the example start date to 160.0 lb, if you hold 1,579 kcal a day.

First week: about 1.0 lb (500 kcal below a TDEE of 2,079).
A straight 3,500-kcal-per-pound projection would say 20.0 weeks. This one is 3.0 weeks longer because your TDEE falls from 2,079 to about 1,955 kcal as you get lighter, so the daily gap shrinks.
Math: each day, TDEE = Mifflin-St Jeor BMR at that day's weight × 1.375; the gap to 1,579 kcal changes weight at 3,500 kcal per lb (7,716 per kg).

Projected weight and TDEE
When	Date	Weight	TDEE
Start	October 31, 2026	180.0 lb	2,079
Week 4.0	November 28, 2026	176.1 lb	2,055
Week 8.0	December 26, 2026	172.4 lb	2,032
Week 12.0	January 23, 2027	168.8 lb	2,010
Week 16.0	February 20, 2027	165.5 lb	1,989
Week 20.0	March 20, 2027	162.3 lb	1,969
Week 23.0	April 10, 2027	160.0 lb	1,955

Real progress is usually slower than any projection: the body adapts to a deficit beyond what weight alone explains, and water hides fat loss for days at a time. Treat the date as the earliest likely, and check it against your own trend in the tracker.

Most goal-date calculators divide the weight to lose by a fixed weekly rate. That assumes your deficit stays the same all the way down, but it does not: a lighter body burns less, so the same intake makes a smaller deficit every week. This calculator recomputes TDEE with the Mifflin-St Jeor equation at each day's projected weight. For the example above, going from 180 to 160 lb on 1,579 kcal takes 23.0 weeks, against 20.0 weeks with a fixed rate.

It is still a simplification. Researchers at the NIH showed that the fixed 3,500-calorie rule overpredicts weight loss over time, and their model also includes the adaptations in energy expenditure that happen during a diet, which this calculator leaves out. Their rule of thumb for an average overweight adult: every 10 kcal a day of lasting change in intake moves weight by about 1 lb in the end, with half of the change reached in about a year and 95% in about three years. Read the date here as the earliest likely date, not a promise.

How long does it take to lose 10, 20 or 30 pounds?

Projected with this calculator, eating 500 or 750 kcal below the starting TDEE and holding that intake:

Person	Daily calories	10 lb	20 lb	30 lb
Woman, 35, 5 ft 5 in, 180 lb, lightly active, −500	1,579	10.7 wk	23.0 wk	37.6 wk
Woman, 35, 5 ft 5 in, 180 lb, lightly active, −750	1,329	7.0 wk	14.6 wk	23.0 wk
Man, 40, 5 ft 10 in, 230 lb, moderately active, −500	2,537	10.9 wk	23.6 wk	39.0 wk
Man, 40, 5 ft 10 in, 230 lb, moderately active, −750	2,287	7.0 wk	14.9 wk	23.6 wk

The first 10 lb come at close to the expected pace; each later 10 lb takes longer. "Levels off first" means TDEE falls to the intake before that much weight is lost, so the deficit has to be reset partway.

How many calories is a pound of fat?

About 3,500 kcal per pound, or roughly 7,700 kcal per kilogram. It is an approximation that holds reasonably well for the first weeks of a diet, which is why every calculator on this site uses it for weekly rates. To lose 1 lb you need a total deficit of about 3,500 kcal: 500 kcal a day for a week, or 250 a day for two weeks. Over months, use the projection above or your own trend, because the rule alone predicts more loss than people see.

Why your weight can level off before the goal

Every intake has a weight where it becomes maintenance. Set your intake from today's TDEE and leave it there, and your weight slides toward that point, slower and slower, without passing it. When the calculator says "Not reached", it shows that weight. The fix is to recalculate after every 10 lb or so and lower the intake a little, or raise activity, while staying above 1,200 kcal (women) or 1,500 kcal (men).

Getting a more accurate date

Use your real TDEE. Log weight and calories for two to four weeks in the adaptive tracker, then plan from the observed number instead of the formula.
Be honest about the intake. The date assumes you eat the number in the box every day, weekends included.
Expect noise. Water and food in the gut swing the scale by a pound or two from day to day. Judge progress on weekly averages; the weight loss percentage calculator shows how far you have come.

Questions

How long will it take me to lose 30 pounds?

At a steady 500 kcal a day below your starting TDEE, about 38 to 39 weeks, roughly nine months, for the two examples in the table above. Smaller people need longer, because the same 30 lb is a bigger share of their weight and their TDEE falls closer to the intake. Enter your own numbers in the calculator; it gives a date, not a range of months.

How fast can I safely lose weight?

The CDC notes that people who lose about 1 to 2 lb a week are more likely to keep it off than people who lose faster. The calculator flags a first-week rate above 2 lb and any intake below 1,200 kcal (women) or 1,500 kcal (men).

Why is my date later than on other calculators?

Most use a fixed weekly rate. This one lowers your TDEE as your weight falls, which adds weeks toward the end. Real progress tends to be slower still, so a later date is the more realistic one.

Does this work for gaining weight?

Yes. Enter a goal above your current weight and an intake above your TDEE; the same daily recalculation applies, and the surplus shrinks as you get heavier.

By Alton Vieira · Updated October 31, 2026. Estimates for healthy adults; not medical advice. How every number is calculated.