Weight loss calculator: your goal date
With a steady deficit you usually lose 1–3 kg a month. The calculator takes 250, 500 or 750 kcal a day off your burn from the Mifflin-St Jeor equation, but never more than 20% of it, and counts about 7,700 kcal per kilo. For example, a 30-year-old woman, 80 kg, 165 cm, lightly active, at 0.5 kg a week gets 1,672 kcal a day and is 5 kg down in about 14 weeks.
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Where the number comes from
The formula, a worked example and where it stops working
How much weight can I lose in a month: the short answer
On a steady deficit most people lose 1-3 kg a month. The calculator uses the deficit calculator's model: 250, 500 or 750 kcal a day below your burn, but no more than 20% of it, and about 7,700 kcal per kilogram. CDC, Losing Weight, checked 19 October 2026 says people who lose about 1-2 pounds (0.5-1 kg) a week are more likely to keep it off. Weight moves unevenly, so treat the date as a guide.
How we calculate
First, your daily burn: resting metabolism from Mifflin MD, St Jeor ST et al., American Journal of Clinical Nutrition, 1990, times an activity factor. The deficit for your pace comes off that: 250, 500 or 750 kcal, but no more than 20% of your burn. That cap is our cautious choice; we could not find a verified source for an exact percentage. That is your daily target, but never below 1,200 kcal for women or 1,500 for men, the top ends of the ranges in NHLBI, Clinical Guidelines on Overweight and Obesity in Adults, 1998. From age 60 the minimum is 1,400 and 1,600, which is our cautious choice.
Then the calculator steps through the weeks. A week adds up seven days of deficit, and by convention 7,700 kcal count as a kilogram, the same ratio as in NHLBI, 1998: a deficit of 500–1,000 kcal a day gives 1–2 lb (0.45–0.9 kg) a week. After each week your weight is lower, your burn is lower too, and the target is recalculated — as if you entered your new weight in the deficit calculator every week. When the weight reaches your goal, you get the date.
An example from the calculator: a 30-year-old woman, 165 cm, 80 kg, lightly active, goal 75 kg, pace 0.5 kg a week. Her target is about 1,672 kcal a day and the goal is 14 weeks away. Why not 10? Taking 500 kcal off is more than 20% of her 2,090 kcal burn, so the deficit is trimmed to 418 kcal, about 0.38 kg a week. As she loses weight her burn drops too, and the deficit shrinks a little more.
How long to lose 5 and 10 kg: women
Same engine as the calculator. For each pace: how much to eat a day and how many weeks 5 and 10 kg take.
| Pace | Eat per day | To lose 5 kg | To lose 10 kg |
|---|---|---|---|
| 0.25 kg/wk | 1,840 kcal | 22 weeks | 44 weeks |
| 0.5 kg/wk | 1,672 kcal | 14 weeks | 28 weeks |
| 0.75 kg/wk | 1,672 kcal | 14 weeks | 28 weeks |
Woman, 30, 80 kg, 165 cm, light activity (×1.375). The deficit is capped at 20% of your burn and the target never drops below 1200 kcal.
How long to lose 5 and 10 kg: men
The man in this table (worked out by the same calculator) is heavier and taller, so his target is higher. At the mild pace the weeks match the woman's, since the 250 kcal deficit is the same. At 0.5 and 0.75 kg he goes faster: 20% of his burn is a bigger number, so the cap trims his deficit less.
| Pace | Eat per day | To lose 5 kg | To lose 10 kg |
|---|---|---|---|
| 0.25 kg/wk | 2,387 kcal | 22 weeks | 44 weeks |
| 0.5 kg/wk | 2,137 kcal | 11 weeks | 22 weeks |
| 0.75 kg/wk | 2,109 kcal | 11 weeks | 22 weeks |
Man, 30, 95 kg, 178 cm, light activity (×1.375). The deficit is capped at 20% of your burn and the target never drops below 1500 kcal.
Why your weight does not follow the timeline
The model only counts fat, while the scales show everything at once: water, food in your stomach, the salt from last night's dinner. Weight easily swings a kilo up and down in a day, and that is not fat. In the first weeks it often drops faster than planned as water goes, and later there are weeks when it stalls even though the deficit is there.
So compare weekly averages, not single days. If the average has not moved for two or three weeks, check your log first: unlogged snacks, oil and drinks eat most deficits. More in the article on why you are not losing weight on a deficit.
Which pace to pick
The US Centers for Disease Control and Prevention (CDC) says people who lose weight gradually and steadily, about 1-2 pounds (0.5-1 kg) a week, are more likely to keep it off than people who lose it quicker. All three paces in the calculator sit inside that range or below it.
A fast pace looks good on paper, but holding it for months is hard. A slow pace you can actually keep usually gets you there sooner than a fast one that falls apart in week three. If the target at the fast pace comes out below your resting metabolism, pick a gentler pace — the calorie deficit calculator explains why.
If the calculator shows a BMI at goal below 18.5, your goal is under the healthy range for your height. Check it with the ideal weight calculator.
The date only comes true if the deficit really holds. The easiest way to see that is a bot that counts calories from a photo: it remembers your target, adds up what you ate each day and keeps a weight diary — type your weight in the chat and it is logged.
Frequently asked questions
How much weight can I lose in a month?
On a deficit of 250-750 kcal a day, roughly 1-3 kg of fat a month. In the first month the scales often show more because of water. The CDC (Losing Weight) says losing about 1-2 pounds (0.5-1 kg) a week makes it more likely to stay off.
How long does it take to lose 10 kg?
It depends on your burn. A 30-year-old woman, 80 kg, 165 cm, lightly active, needs about 28 weeks at 0.5 kg a week, because the 20% cap trims her deficit. A 30-year-old man, 95 kg, 178 cm, needs about 22 weeks. At the mild pace both need about 44 weeks. The calculator above works out your own date.
Can I lose 5 kg in a week?
Not of fat. By the calculator's model 5 kg is about 38,500 kcal of deficit, over 5,000 a day. If the scales show 5 kg less after a week, it is mostly water, and it comes back.
Why is my weight not moving on a deficit?
Usually water and unlogged food: snacks, oil, drinks. Compare weekly averages rather than days. The reasons are covered in not losing weight on a calorie deficit.
How accurate is the weight loss date?
It is a forecast from an average model. Real weight moves in waves, and people of the same height and weight burn different amounts. Recalculate every 4-5 kg or if your weight stalls for two or three weeks.
Reminders
Water and weight