Calorie Calculator

Estimate your daily calorie maintenance (TDEE) plus cut and bulk targets using the Mifflin-St Jeor equation.

About this calculator

Your daily calorie needs depend on your basal metabolic rate (BMR) — the calories your body burns at rest — plus the calories you burn through activity. This calculator estimates both using the Mifflin-St Jeor equation, the most accurate of the standard BMR formulas, and shows targets for losing, maintaining, or gaining weight.

How it works

BMR (basal metabolic rate) is the energy your body uses to keep you alive — heartbeat, breathing, brain activity, tissue maintenance. The Mifflin-St Jeor equation gives BMR from your weight, height, age and sex with about ±10% accuracy for most people.

TDEE (total daily energy expenditure) is BMR multiplied by an activity factor: 1.2 for sedentary (desk job, no exercise), 1.375 for light (1–3 days/week), 1.55 for moderate (3–5 days/week), 1.725 for active (6–7 days/week), 1.9 for very active (athletes, manual labour, twice-daily training).

To lose weight, eat below TDEE. A 500 kcal/day deficit produces roughly 0.5 kg / 1 lb per week of weight loss in the short term. A 250 kcal deficit is gentler and easier to sustain — recommended for most people. To gain muscle, eat about 250 kcal above TDEE while training resistance.

Mifflin-St Jeor was published in 1990 and replaced the older Harris-Benedict equation. For most adults under 60 it's within 10% of the true value as measured by indirect calorimetry. Outliers: very lean athletes (often higher than calculated), people with thyroid conditions, and very obese individuals (where the equation overestimates by 5–15%).

Formula

Mifflin-St Jeor BMR:
  male:    BMR = 10·kg + 6.25·cm − 5·age + 5
  female:  BMR = 10·kg + 6.25·cm − 5·age − 161

TDEE = BMR × activity_factor
  sedentary 1.2 · light 1.375 · moderate 1.55 · active 1.725 · very-active 1.9

Examples

30-year-old male, 80 kg, 180 cm, moderate activity

A moderately active 30-year-old male of 80 kg / 180 cm needs about 2,759 kcal/day to maintain weight. Eating 2,509 kcal/day produces about 0.25 kg/week of loss.

Result: BMR ≈ 1,780 kcal — TDEE ≈ 2,759 kcal — Mild cut ≈ 2,509 kcal

35-year-old female, 65 kg, 168 cm, light activity

A lightly active 35-year-old female of 65 kg / 168 cm needs about 1,910 kcal/day to maintain weight.

Result: BMR ≈ 1,389 kcal — TDEE ≈ 1,910 kcal

Frequently asked questions

How accurate is Mifflin-St Jeor? +

For most adults, within ±10% of true BMR measured by indirect calorimetry. Less accurate for very lean, very obese, elderly, or people with thyroid disorders.

Should I eat exactly my TDEE? +

Use it as a starting point and adjust based on real-world results over 2–4 weeks. If you're maintaining weight, your TDEE estimate is good. If not, adjust by 100–200 kcal.

Can I lose more than 0.5 kg per week? +

Physiologically yes, but sustained deficits over 750 kcal/day tend to cause muscle loss, low energy, hormonal disruption and rebound eating. Slow loss almost always wins long-term.

Is this medical advice? +

No. The calculator gives a population-average estimate. If you have a thyroid condition, eating disorder history, or other health concerns, work with a registered dietitian or physician.

Why Mifflin-St Jeor and not Harris-Benedict? +

Mifflin-St Jeor (1990) was developed on a larger, more modern population and is more accurate than Harris-Benedict (1919) for most people, especially those with higher body weight.