Calorie Calculator
Enter your sex, age, weight, height and activity level. The calculator returns BMR, daily maintenance calories, a cutting target (-500 kcal) and a lean-bulk target (+300 kcal).
Maintenance calories (kcal/day)
2,633
- BMR — at rest (kcal/day)
- 1,699
- Cut — lose ~1 lb / week (kcal/day)
- 2,133
- Bulk — lean gain (kcal/day)
- 2,933
Mifflin-St Jeor BMR multiplied by an activity factor (1.2 sedentary → 1.9 extra active) gives daily maintenance calories. Subtract 500 kcal/day for ~1 lb/week fat loss; add 300 kcal/day for a lean bulk. Educational estimate, not medical advice — see a registered dietitian for prescriptive plans.
How to use this calculator
Pick your sex, type your age in years, weight in kilograms and height in centimetres, then choose the activity level closest to your weekly routine. Maintenance calories are how much you need to keep weight stable; the cut figure removes 500 kcal/day for steady fat loss; the bulk figure adds 300 kcal/day for slow muscle gain.
How the calculation works
BMR (the calories your body burns at complete rest) is estimated using the Mifflin-St Jeor equation, which the Academy of Nutrition and Dietetics rates as the most accurate predictor for healthy adults. The formula is 10·kg + 6.25·cm − 5·age + 5 for men, or − 161 for women. BMR is then multiplied by an activity factor (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extra active) to give total daily energy expenditure (TDEE).
Worked example
A 30-year-old man, 80 kg and 180 cm, training moderately 3-5 days a week. BMR = 10·80 + 6.25·180 − 5·30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal. Multiplying by the 1.55 moderate factor gives a maintenance TDEE of 2,759 kcal/day. Cutting target ≈ 2,259 kcal; lean-bulk target ≈ 3,059 kcal.
Frequently asked questions
How accurate is the Mifflin-St Jeor BMR formula?
For healthy adults aged 19-78 it predicts measured BMR within roughly ±10 % for most people. Group accuracy beats older formulas like Harris-Benedict, but individual variation in metabolism, body composition and adaptive thermogenesis means the number is a starting estimate, not a precise prescription. Track your weight for two weeks at the calculated maintenance level and adjust ±100-200 kcal/day if you drift.
Why does the calculator ignore body-fat percentage?
Mifflin-St Jeor uses only height, weight, age and sex by design — its accuracy was validated on those inputs alone. If you know your body-fat % accurately (DEXA scan, not bioimpedance scales), the Katch-McArdle equation BMR = 370 + 21.6·LBM(kg) is a better fit for very lean or very muscular people. Most users overestimate lean mass, so we default to Mifflin-St Jeor.
How big a deficit should I run to lose weight?
A 500 kcal/day deficit averages out to about 1 lb (0.45 kg) of fat per week, the rate the CDC and NHS describe as sustainable. Larger deficits (750-1,000 kcal/day) work short-term but tend to shed muscle, tank training quality and rebound when the diet ends. Stick within 20 % below maintenance for cuts longer than a few weeks.
What activity level should I pick?
Be honest — most desk workers who go to the gym 3 times a week are "lightly active" (1.375), not "moderate". Moderate (1.55) suits people doing structured exercise 4-5 hours a week. Very active (1.725) is for athletes training daily. Extra active (1.9) is reserved for manual labourers or twice-a-day training. Overestimating activity is the single biggest source of calorie-tracking failure.
Is this medical advice?
No. This calculator is a general educational tool based on a published equation. It is not a substitute for advice from a registered dietitian, GP or sports physician — particularly if you are pregnant, breastfeeding, under 18, over 65, recovering from an eating disorder, or managing a metabolic condition such as diabetes or thyroid disease. Use the number as a starting point and seek qualified guidance for prescriptive plans.
Why are my "bulk" calories only 300 above maintenance?
Lean-gain protocols add a small surplus (200-400 kcal/day) so most of the new tissue is muscle rather than fat. Larger surpluses speed scale weight gain but the extra is mostly fat, which then has to be cut back off. A 300 kcal/day surplus targets roughly 0.25-0.5 lb of weight gain per week — slow on paper but efficient in body composition.