How accurate is the result?

Mifflin-St Jeor estimates BMR within ~±10 % for most people — a very good starting point. Your real response to the calories is the final truth.

Why no more aggressive deficits?

Deficits beyond 500–700 kcal accelerate muscle loss, disrupt hormones, ruin training and sleep — and almost always end in yo-yo. Patience beats crash. That's Chanto.

What if I train on some days and not others?

Pick your activity level as a weekly average. You can vary calories between training and rest days — the weekly total is what counts.

Should I refeed or have cheat days?

For most people, consistent moderate deficits across the week beat complex refeed schemes. Plan social meals deliberately and keep the rest clean.

Why 2 g of protein per kg?

For active people building or preserving muscle, research points to ~1.6–2.2 g/kg. 2.0 g is a robust, simple anchor inside that corridor.

Do I need an account or a premium plan?

No. Every tool in the Performance Lab is permanently free — no ads, no sign-up, no limits.

Calculator · Performance Lab

Calorie Calculator

Calculate your basal metabolic rate, total daily energy expenditure and target calories — precisely, via Mifflin-St Jeor.

Ergebnis

Basal metabolic rate (BMR): 1,790kcal/day
Total daily energy expenditure (TDEE): 2,775kcal/day
Target calories (maintain): 2,775kcal/day
Protein recommendation: 160g/day

Explained

What this calculator does for you

Your calorie needs have two layers: your basal metabolic rate (BMR) — the energy your body burns at complete rest just to function — and the activity component added by movement, training and daily life. The sum is your total daily energy expenditure (TDEE).

This number is the starting point of any honest nutrition plan. To lose fat, eat deliberately below it. To build muscle, eat slightly above it. To maintain, hit it. Everything else is guessing.

The calculator gives an estimate — a very good one. Reality settles over weeks at the mirror and the scale. Adjust in 100 kcal steps from there.

Science

Scientific background

The Mifflin-St Jeor equation (1990) is today's most accurate standard for estimating BMR in healthy adults. It has replaced the older Harris-Benedict equation in most textbooks.

The activity multipliers (1.2 to 1.9) are a long-established convention. They are necessarily coarse — no multiplier can precisely separate 'I walk once a week' from 'I walk an hour every day'.

For more precision, track honestly for 7–14 days (calories in, weight out) and correct the estimate by the observed change.

Examples

Practical examples

Example A — 28, male, 80 kg, 180 cm, moderately active, maintain

BMR ≈ 1,780 kcal, TDEE ≈ 2,760 kcal. Maintain: ~2,760 kcal/day. Lean bulk: ~3,060 kcal/day. Fat loss: ~2,260 kcal/day.

Example B — 24, female, 62 kg, 168 cm, lightly active, fat loss

BMR ≈ 1,400 kcal, TDEE ≈ 1,925 kcal. Fat-loss target: ~1,425 kcal/day — close to the safe floor. For small people, prefer a gentler deficit plus more activity.

Avoid these

Common mistakes

01Picking too high an activity level. A standing desk plus 3× lifting is 'moderate', not 'extreme'.
02Re-adjusting calories within days. Give any plan two to three weeks.
03Neglecting protein in a deficit. This is exactly when it matters most for protecting muscle.
04Ignoring weekends. The weekly total decides — not Monday.

Recommendations

Further recommendations

01Weigh yourself in the morning, fasted, three to five days a week. Work with a 7-day average, not single-day values.
02Anchor every meal with a clear protein source. It makes hitting daily targets easy.
03Drink enough water. Hunger and thirst are often confused — especially in a deficit.
04Treat sleep like training. Poor sleep shifts hunger hormones and makes deficits unnecessarily hard.

FAQ

Frequently asked questions

How accurate is the result?: Mifflin-St Jeor estimates BMR within ~±10 % for most people — a very good starting point. Your real response to the calories is the final truth.
Why no more aggressive deficits?: Deficits beyond 500–700 kcal accelerate muscle loss, disrupt hormones, ruin training and sleep — and almost always end in yo-yo. Patience beats crash. That's Chanto.
What if I train on some days and not others?: Pick your activity level as a weekly average. You can vary calories between training and rest days — the weekly total is what counts.
Should I refeed or have cheat days?: For most people, consistent moderate deficits across the week beat complex refeed schemes. Plan social meals deliberately and keep the rest clean.
Why 2 g of protein per kg?: For active people building or preserving muscle, research points to ~1.6–2.2 g/kg. 2.0 g is a robust, simple anchor inside that corridor.
Do I need an account or a premium plan?: No. Every tool in the Performance Lab is permanently free — no ads, no sign-up, no limits.

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