Calorie Calculator: daily calories to lose or gain weight

Work out how many calories you burn in a day and how many to eat to keep your weight steady, lose weight or gain it at a safe rate.

Daily calories for each goal
Goal	Calories a day
Maintain weight	1,918 kcal
Lose about 0.25 kg (½ lb) a week	1,668 kcal
Lose about 0.5 kg (1 lb) a week	1,418 kcal
Lose about 1 kg (2 lb) a week	918 kcal ⚠ under 1,200: only with medical supervision
Gain about 0.25 kg (½ lb) a week	2,168 kcal
Gain about 0.5 kg (1 lb) a week	2,418 kcal

How the calculator works

It estimates your BMR, the energy you burn at complete rest, with the Mifflin–St Jeor equation: women 10 × kg + 6.25 × cm − 5 × age − 161; men the same + 5 instead of − 161.
It multiplies BMR by an activity factor, from 1.2 for a desk job with little exercise to 1.9 for very hard training, to get your maintenance calories.
It subtracts or adds 250, 500 or 1,000 calories a day for each goal. NIH guidance puts a 500 to 1,000 calorie daily deficit at roughly 1 to 2 lb (0.5 to 1 kg) of weight loss a week.

Worked example

A 35-year-old woman, 165 cm and 70 kg, who exercises lightly 1 to 3 days a week: BMR = 700 + 1,031.25 − 175 − 161 = 1,395 kcal. × 1.375 for light activity = 1,918 kcal a day to stay at the same weight. To lose about 0.5 kg (1 lb) a week she would eat about 1,418 kcal a day.

Make it work for you

Treat the number as a starting point: everyone burns a little more or less than a formula predicts. If your weight trend hasn't changed after a few weeks, adjust your target a little.
Protein and fibre help you feel full on fewer calories. See how to split your calories with the macro calculator.
Check where you are with the BMI calculator and set a goal with the ideal weight calculator.

Sources, checked 2 October 2026: Mifflin MD, St Jeor ST et al., American Journal of Clinical Nutrition 1990;51:241–7; NIH National Heart, Lung, and Blood Institute, The Practical Guide to overweight and obesity in adults; the NHS on calories and its 12-week weight loss plan; Harvard Health. For a model of how weight changes over time, see the NIH Body Weight Planner. Not medical advice.

Frequently asked questions

How many calories should I eat to lose weight?

Eat about 500 to 1,000 calories a day less than your maintenance calories. The US National Heart, Lung, and Blood Institute says that leads to a loss of 1 to 2 pounds (about 0.5 to 1 kg) a week, the rate the NHS also recommends as safe and sustainable.

What's the lowest calorie intake that's safe?

Harvard Health advises not going below 1,200 calories a day for women or 1,500 for men except under medical supervision. The calculator flags any target below those levels. Very low-calorie diets should only be done with a doctor.

Why has my weight loss slowed down?

As you lose weight your body needs fewer calories, so the same intake creates a smaller deficit. Recalculate with your new weight every few kilos. Water weight also makes the scales jump around from day to day, so look at the trend over weeks.

How many calories does an average adult need?

The NHS uses about 2,000 kcal a day for an average woman and 2,500 kcal for an average man. Your own needs depend on your age, size and how active you are, which is what this calculator estimates.

Are calories and kcal the same?

On food labels, yes: a food Calorie is a kilocalorie (kcal), 1,000 small calories. 1 kcal = 4.184 kJ, so 2,000 kcal is about 8,400 kJ.