Calorie Calculator
Find out how many calories you need each day to lose, gain or maintain weight — using the Mifflin-St Jeor equation and your activity level, in metric or imperial.
Daily calorie needs
Mifflin-St Jeor TDEE. Metric or imperial.
A guide only, not medical or dietary advice. The NHS general daily guide is 2,500 (men) and 2,000 (women) — see NHS calories.
How many calories do you need a day?
Your daily calorie need depends on your age, sex, height, weight and activity level. We first work out your Basal Metabolic Rate with the Mifflin-St Jeor equation, then multiply by an activity factor to get your maintenance calories (TDEE). Adjusting up or down from that figure is how you gain or lose weight.
As a general guide the NHS uses 2,500 calories a day for men and 2,000 for women. To lose about 0.5 kg a week, eat roughly 500 calories a day below maintenance; a 1 kg/week loss means a 1,000-calorie deficit, which suits fewer people.
What a calorie change does
| Goal | Daily change | Weekly effect |
|---|---|---|
| Maintain | 0 | Stable weight |
| Lose slowly | −500 kcal | ≈ 0.5 kg loss |
| Lose faster | −1,000 kcal | ≈ 1 kg loss |
| Gain | +500 kcal | ≈ 0.5 kg gain |
Based on roughly 7,700 calories per kg of body fat. Source: NHS — understanding calories.
Making it safe and sustainable
The NHS advises not dropping below about 1,500 calories (men) or 1,200 (women) without medical supervision. Slow, steady loss is easier to keep off than crash dieting. Calories are only part of the picture — food quality, protein and activity all matter. Check your weight category with our BMI calculator and your resting burn with the BMR calculator.
Frequently asked questions
How many calories should I eat a day?
It depends on you, but the NHS general guide is 2,500 for men and 2,000 for women. This calculator personalises that using your age, sex, height, weight and activity level via the Mifflin-St Jeor equation.
How do I create a calorie deficit to lose weight?
Eat fewer calories than your maintenance level. A deficit of about 500 calories a day gives roughly 0.5 kg of weight loss a week, since around 7,700 calories equals 1 kg of body fat.
What is TDEE?
TDEE stands for Total Daily Energy Expenditure — your maintenance calories. It's your Basal Metabolic Rate multiplied by an activity factor, representing all the calories you burn in a typical day.
Is it safe to eat 1,200 calories a day?
The NHS suggests not going below about 1,200 calories for women or 1,500 for men without medical advice, as very low intakes can be unsafe and hard to sustain. Aim for a gentle deficit instead.
Why does my calorie need fall as I lose weight?
A lighter body burns fewer calories at rest, so your maintenance level drops as you lose weight. Recalculating every few kilograms keeps your target accurate and avoids a stall.