Weight Loss Calculator
Tell us where you are, where you want to be and how long you have. We work out the daily calories and tell you if the plan is realistic.
This calculator gives general estimates for information only. It is not medical advice and does not replace a consultation with a doctor or other qualified health professional.
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The formula
Weekly loss = (current - goal weight) / weeks. Daily calories = maintenance - (weekly loss x 7,700 / 7).
How the plan is built
We estimate your maintenance calories, work out how much weight you need to lose per week to hit your goal in the time you chose, and convert that into a daily calorie target.
Is your goal realistic?
We flag plans that would mean eating below a safe minimum, or losing more than about 1 percent of your body weight a week. If that happens, stretch the time frame. A goal reached a month later is better than one abandoned.
Why the scale slows down
As you lose weight your body needs fewer calories, so the same deficit produces less loss over time. Recalculate every few kilos to keep the plan accurate.
Examples to check
Type these into the calculator above to see how it behaves. Every result below was produced by the same calculator code that runs on this page.
| What you enter | What you get |
|---|---|
| Male; Age (years): 30; Height (cm): 180; Weight (kg): 80; Moderate (3-5 days a week); Goal weight (kg): 74; Weeks to reach it: 12 | Daily calories to hit your goal: 2,209 kcal/day |
| Female; Age (years): 30; Height (cm): 165; Weight (kg): 65; Light (exercise 1-3 days a week); Goal weight (kg): 59; Weeks to reach it: 12 | Daily calories to hit your goal: 1,334 kcal/day |
| Female; Age (years): 40; Height (cm): 160; Weight (kg): 72; Sedentary (little or no exercise); Goal weight (kg): 66; Weeks to reach it: 12 | Daily calories to hit your goal: 1,081 kcal/day |
Weight Loss Calculator: frequently asked questions
How accurate are calorie calculators?
They are estimates, usually within about 10 percent. Your real needs depend on genetics, muscle, sleep and how much you move outside of exercise. Track your weight for two to three weeks and adjust by 100 to 200 calories if it is not moving as expected.
How many calories is a pound of fat?
About 3,500 calories per pound, or 7,700 per kilogram. This is a handy rule of thumb, but real weight loss slows down over time as your body adapts.
Can I rely on this result as medical advice?
No. It is a general estimate for information only. It cannot replace a check-up, and your doctor can interpret the numbers for your own situation.
Is what I enter in this calculator saved or sent anywhere?
No. The calculation runs in your browser, so what you enter is not sent to our servers. We only count, anonymously, whether a tool ran successfully.
Is this calculator free to use?
Yes. It is free, needs no sign-up and has no usage limit.
Last reviewed: October 3, 2026