Health & Fitness
BMR Calculator
BMR Calculator is a browser-based calculator tool on CalcToolsBase. Estimate your Basal Metabolic Rate — the calories your body burns at complete rest — plus your daily total. To use it, enter your values and view the result directly in your browser — no signup and nothing to install.
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 Calculator is built to work out your BMR without a server round-trip. Provide your weight, height, age and sex and it uses the Mifflin–St Jeor equation to produce your basal metabolic rate in kcal/day, instantly and entirely in your browser, which makes it handy for quick checks and repeat runs.
BMR is an estimate based on weight, height, age, and sex. Real metabolism varies with body composition, genetics, hormones, and health, so use the figure as a starting point rather than an exact requirement.
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
BMR for setting realistic training goals
BMR when adjusting diet and exercise
BMR as a general wellness guide
BMR when logging weekly numbers
BMR in personal-training sessions
BMR 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.