Calorie Calculator

A daily calorie calculator estimates your Total Daily Energy Expenditure (TDEE) — the calories you burn in 24 hours when food intake roughly matches activity. The NHS uses a general guideline of 2,000 kcal/day for women and 2,500 kcal/day for men, but these averages mask huge individual variation. A 25-year-old male labourer can burn 3,500+ kcal a day, while a 65-year-old sedentary woman might need just 1,600. To find your personal number this calculator uses the Mifflin-St Jeor equation — the most accurate widely-used BMR formula, recommended by the American Dietetic Association — and multiplies the result by an activity factor. The Mifflin-St Jeor BMR formula is: men BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5; women BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161. BMR is what you burn at complete rest — heart, lungs, organs, basic cellular function. To get TDEE you multiply by activity factor: 1.2 sedentary (desk job, no exercise), 1.375 light (light exercise 1-3 days/week), 1.55 moderate (3-5 days/week), 1.725 active (6-7 days/week), 1.9 very active (athlete or physical job + hard training). For weight management the maths is simple but cruel: 1 lb (0.45 kg) of body fat contains roughly 3,500 kcal of energy. A consistent 500 kcal/day deficit produces about 1 lb/week loss; a 1,000 kcal deficit produces about 2 lb/week (the maximum safe rate for most adults). Conversely, eating 500 kcal/day above TDEE adds about 1 lb/week — relevant for muscle-building bulks. The calculator shows your maintenance calories plus weight-loss targets at -250, -500 and -1000 kcal, and weight-gain targets at +250 and +500. Caveats. The Mifflin-St Jeor equation has roughly ±10% individual variation — your real metabolism could be 1,800 kcal/day when the formula says 2,000. Track for 2-3 weeks and adjust if reality diverges. The activity multipliers consistently overestimate non-exercise calories burned, so most people find they need to use a one-step-lower activity bracket than self-described. The calculator does not handle medical conditions affecting metabolism (hypo/hyperthyroidism, PCOS, GLP-1 medications like Mounjaro or Ozempic which suppress appetite and may alter TDEE), pregnancy/breastfeeding additional needs (+300/+500 kcal), or athletes with unusual carbohydrate periodisation needs. For weight target setting use the Ideal Weight Calculator; for BMI classification use the BMI Calculator.