BMR Calculator

Units Formula

Inputs

Age Sex

Height (cm) Weight (kg)

Body fat % (optional)

Katch–McArdle uses lean mass from body-fat %.

Press Enter in any field to calculate. Data stays local.

Results

BMR: — kcal/day

Using Mifflin–St Jeor.

Quick TDEE preview

Sedentary ×1.2: — Light ×1.375: — Moderate ×1.55: — Very ×1.725: — Extra ×1.9: —

Compare formulas

Formula	BMR (kcal/day)
Mifflin–St Jeor	—
Harris–Benedict	—
Katch–McArdle	—

BMR is a resting estimate. Not for children, pregnancy, or medical use.

Estimate how many calories your body burns at rest using Mifflin–St Jeor, Katch–McArdle (with body-fat %) or Harris–Benedict. Enter your details to get your BMR and a quick TDEE preview for common activity levels. All calculations run locally — we don’t store your data.

Key features

Three formulas: Mifflin–St Jeor (default), Katch–McArdle (uses body-fat %), Harris–Benedict (Revised)
Units: metric, imperial and UK stones/ft/in
Quick TDEE chips to estimate maintenance from BMR
Copy and Share (prefill) options
Mobile-first, accessible, client-side only

How to Use the BMR Calculator

Choose units and formula.
Enter age, sex, height, weight (and body-fat % if using Katch–McArdle).
Click Calculate to see your BMR and TDEE previews.
Use our Calorie Calculator to set goals and macros.

How it works

BMR = calories you’d burn in 24 hours at rest (breathing, circulation, cell repair).
Common formulas
- Mifflin–St Jeor: BMR = 10·kg + 6.25·cm − 5·age + s (s = +5 male, −161 female)
- Harris–Benedict (Revised): sex-specific equations using kg/cm/age
- Katch–McArdle: BMR = 370 + 21.6·LBM (LBM from body-fat %)
TDEE ≈ BMR × activity (e.g., ×1.2 sedentary → ×1.9 extra active).

When to use BMR vs TDEE

BMR: baseline physiology, comparisons over time, plan starting point
TDEE: day-to-day calorie target (use our Calorie Calculator to apply goals)

FAQs

Q1:Which formula is most accurate?
Mifflin–St Jeor is a strong default. If you know body-fat %, Katch–McArdle can be more precise.

Q2:Why do different formulas give different numbers?
Each was derived from different datasets; expect small variations. Use one method consistently.

Q3:Do you support stones/feet/inches?
Yes — switch to UK units.

Q4:Is BMR the same as resting metabolic rate (RMR)?
They’re closely related estimates; calculators often use the terms interchangeably.

Q5:Do you store my data?
No — everything runs locally in your browser.

Q6:Is this suitable for children or pregnancy?
No. Seek advice from a qualified clinician or dietitian.