TDEE & calorie-deficit calculator
Work out how many calories you burn a day, then a safe daily target to lose weight — kept to the NHS lower limits, so the number is realistic rather than crash-diet territory.
Updated 2 November 2026
Fill in your details to see your daily calories and a safe deficit.
An estimate from the Mifflin-St Jeor equation, not a personal diet plan. Aim to lose about 0.5 to 1 kg a week. If you have a health condition or a history of an eating disorder, get advice from a GP or dietitian.
Turning the number into weight loss
A pound of fat holds roughly 3,500 calories, so a 500-calorie daily deficit is about 0.5 kg a week. Faster isn’t better: very low intakes cost you muscle and are hard to sustain, which is why this tool won’t take you below the NHS floor. Pair the deficit with enough protein and some strength training to keep muscle while the fat comes off.
Next steps
Check where you are with the BMI & healthy-weight calculator, set a muscle-protecting target with the protein calculator, and see whether an NHS route applies with the NHS injection checker.
Common questions
- What is TDEE?
- TDEE is your Total Daily Energy Expenditure — roughly the calories you burn in a day. It's your BMR (what you'd burn at complete rest) multiplied by an activity factor. Eat around your TDEE to maintain weight; eat below it to lose.
- How is it calculated?
- This calculator uses the Mifflin-St Jeor equation for BMR, which is the one NHS and dietetic practice tend to use. It needs your weight, height, age and sex, then applies an activity multiplier from 1.2 (sedentary) to 1.9 (extra active).
- What's a safe calorie deficit to lose weight?
- The NHS suggests losing about 0.5 to 1 kg (1 to 2 lb) a week, which is roughly a 500 to 600 kcal daily deficit. This tool shows a steady and a faster target, but holds both to the NHS lower limits (about 1,400 kcal for women, 1,500 for men) — going lower than that without supervision isn't recommended.
- How much protein and water should I have?
- On a deficit, protein protects muscle: work out a target with the protein calculator. For fluid, aim for roughly 1.5 to 2 litres a day, and more in the heat, with exercise, or if a GLP-1 is giving you sickness or diarrhoea.
- Do I need to count calories on weight-loss injections?
- Medicines like Mounjaro and Wegovy cut appetite, so many people naturally eat less without counting. If you do track, use this as a guide, prioritise protein and fibre, and don't drop below the floor. Your prescriber can advise.
BMR from the Mifflin-St Jeor equation; safe-loss guidance from the NHS.