Health & Fitness
BMR Calculator
BMR: BMR Calculator estimates basal metabolic rate (resting energy) with the Mifflin-St Jeor equation. Worked through below with real figures, and the calculator repeats the working on your own inputs — free, on-device, instant.
From your weight, height, age and sex, BMR Calculator computes your basal metabolic rate in kcal/day via the Mifflin–St Jeor equation. No accounts, no uploads — just an instant way to work out your BMR.
About this calculator
BMR is easiest to get wrong in the setup, not the arithmetic. BMR Calculator estimates basal metabolic rate (resting energy) with the Mifflin-St Jeor equation. It matters when you want a quick screening number before deciding whether a habit, plan or measurement deserves a closer look. The worked example on this page (Using the Mifflin–St Jeor equation for a 30-year-old woman, 60 kg, 165 cm : BMR = 10 × 60 + 6.25 × 165 − 5 × 30 − 161 = 600 + 1,031.25 − 150 − 161 = 1,320 kcal/day .) shows the full substitution; the calculator above runs the same working on your own numbers, in your browser, with nothing uploaded.
How to use
- Enter your weight, height, and age to start.
- Choose your sex so the correct equation is applied.
- Pick the activity level that best matches your week.
- Press Calculate to see BMR and an estimated daily total.
Why use BMR Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Educational
Uses common estimation formulas for educational purposes. Results are not medical advice and should not replace professional guidance.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Clear about formulas used and their limits, with disclaimers where they matter.
Common uses
Use it for setting realistic training goals
Use it when adjusting diet and exercise
BMR as a general wellness guide
Use it when logging weekly numbers
BMR in personal-training sessions
Use it when planning a fitness routine
Technical notes
BMR Calculator estimates basal metabolic rate (resting energy) with the Mifflin-St Jeor equation.
These are general-population estimates and not a substitute for advice from a qualified clinician.
Because it runs locally, results appear instantly with no server round-trip.
Worked example
Using the Mifflin–St Jeor equation for a 30-year-old woman, 60 kg, 165 cm: BMR = 10 × 60 + 6.25 × 165 − 5 × 30 − 161 = 600 + 1,031.25 − 150 − 161 = 1,320 kcal/day. For men the final constant is +5 instead of −161. BMR is energy at complete rest — daily needs are higher once activity is included.
FAQ
Which BMR formula is used?
This tool uses the Mifflin–St Jeor equation, which is widely regarded as one of the more accurate predictive formulas for resting metabolism in healthy adults.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest; TDEE multiplies BMR by an activity factor to estimate everything you burn in a typical day, including movement and digestion.
Why does sex change the result?
The equation adds a constant for males and subtracts one for females, reflecting average differences in lean mass, so selecting the correct sex matters.
Does the BMR Calculator send my data to a server?
No. The BMR Calculator runs entirely in your browser — your inputs never leave your device, and nothing is uploaded or stored.