Most adults need between 1,600–3,000 calories per day depending on age, sex, weight and activity level. This calculator uses the Mifflin-St Jeor equation — the most accurate formula recognised by the Academy of Nutrition and Dietetics — to give you a personalised number.

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to stay alive. TDEE (Total Daily Energy Expenditure) multiplies BMR by your activity level to give your real daily calorie burn including exercise and movement.

To lose 0.5 kg (1 lb) per week, aim for a daily deficit of about 500 calories below your TDEE. This is considered safe and sustainable by the NHS, CDC and WHO. Never go below 1,200 calories (women) or 1,500 calories (men) without medical supervision.

We use the Mifflin-St Jeor equation (1990), published in the American Journal of Clinical Nutrition. It is widely accepted as the most accurate BMR formula for most people. For men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. For women: same but −161 instead of +5.

The European Food Safety Authority recommends approximately 35 ml of water per kg of body weight per day. This tool calculates your personalised recommendation. Active individuals and those in hot climates need more.