Online CalcKit

Calorie Needs Calculator

Calculate your BMR and total daily energy needs from age, sex, height, weight, and activity level — using the Mifflin-St Jeor equation.

Units:
Sex:

At rest your body burns about 1,699 kcal a day (BMR). Adjusting for your activity level, your total daily energy expenditure is 2,633 kcal — the calories you'd eat to maintain weight.

BMR (at rest) 1,699 kcal
TDEE (with activity) 2,633 kcal

Daily calories by goal

Lose ~1 kg/wk 1,633 kcal −1000 kcal
Lose ~0.5 kg/wk 2,133 kcal −500 kcal
Maintain 2,633 kcal TDEE
Gain ~0.5 kg/wk 3,133 kcal +500 kcal

Results update as you type. The Mifflin-St Jeor equation is the most accurate widely used formula at population level, but individual energy expenditure varies — treat the numbers as a starting estimate, not a prescription.

Formula

The Mifflin-St Jeor BMR equation: BMR = 10·kg + 6.25·cm − 5·age + s, where s = +5 for males, s = −161 for females. TDEE is BMR multiplied by an activity factor (sedentary 1.2 → extra-active 1.9). Goal calories are TDEE shifted by ±500 or ±1000 — the latter giving roughly 1 kg of weight change per week (3,500 kcal ≈ 0.45 kg of fat).

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Frequently asked questions

What's the difference between BMR and TDEE?

BMR is what your body burns completely at rest — keeping organs running and core temperature stable. TDEE adds all the daily activity on top: walking, work, exercise, digestion. TDEE is the figure you'd eat to keep weight stable.

How accurate is the Mifflin-St Jeor formula?

It's the most accurate widely-used BMR equation at population level — replaced Harris-Benedict in clinical use through the 1990s and 2000s. Individual variation is still ±10% or more (genetics, body composition, age-related metabolic adaptation), so treat the figure as a calibrated starting estimate, not a precise daily target.

Are calorie units the same as kilocalories?

On nutrition labels and in dietary advice, yes — 'calories' (capital C, sometimes) is shorthand for kilocalories (kcal). One kcal is the energy to raise 1 kg of water by 1°C. The 'calorie' as a small physics unit (1/1000th of a kcal) doesn't appear in dietetics. Some EU labels show both kcal and kilojoules (kJ); 1 kcal ≈ 4.184 kJ.

What activity level should I pick?

Be honest. 'Sedentary' = desk work, minimal walking. 'Lightly active' = 1–3 light sessions/week or daily walking. 'Moderately active' = 3–5 structured workouts. 'Very active' = 6–7 sessions OR a physical job. 'Extra active' = serious training plus heavy physical work. Most people overestimate their activity by one notch — if you're tracking weight and not losing on the suggested deficit, drop a level.

Is the 1,200 kcal floor universal?

It's a conservative rule of thumb for adult women; ~1,500 is more often used for adult men. Both reflect that very low intakes make meeting micronutrient targets without supplementation difficult, and that metabolism adapts down. EU national guidelines vary slightly (Germany's DGE, France's ANSES, etc.) but all recommend gradual deficits over very-low-calorie diets except under clinical supervision.

Does this work for athletes?

It gives a baseline. Endurance and strength athletes commonly need significantly more than the formula predicts, especially during training blocks (extra 500–1500 kcal/day during heavy training is normal for serious athletes). Use the 'extra active' multiplier as a starting point, then adjust based on how your weight, performance, and recovery respond over several weeks.