BMR Calculator
Basal metabolic rate — calories burned at complete rest — plus daily needs by activity level.
Your figures
Result
How to use this tool
- Enter your own figures over the defaults — Weight, Height, Age and the rest.
- The answer updates as you type. There is no button, and nothing is sent anywhere.
- Change one input at a time to see how sensitive the answer is to it.
Uses the Mifflin-St Jeor equation, generally considered the most accurate of the common formulas. Individual metabolism still varies by roughly 10% either way.
How it works
This takes 4 inputs — weight, height, age, sex at birth — and returns bmr, sedentary (×1.2), lightly active (×1.375), moderately active (×1.55) and very active (×1.725). The whole calculation happens in this page as you type: there is no submit button, no request, and nothing stored.
A worked example
Worked through with the figures the page already has in it: weight of 70 kg and height of 175 cm, and the rest as shown, giving bmr of 1,649 kcal/day. These numbers come from running the calculator’s own code, not from being typed in here, so they cannot drift away from what you see on screen.
Starting from:
- Weight: 70 kg
- Height: 175 cm
- Age: 30 years
- Sex at birth: Male
| Result | Value |
|---|---|
| BMR | 1,649 kcal/day |
| Sedentary (×1.2) | 1,979 kcal |
| Lightly active (×1.375) | 2,267 kcal |
| Moderately active (×1.55) | 2,556 kcal |
| Very active (×1.725) | 2,844 kcal |
BMR Calculator — frequently asked questions
What is BMR?
The energy your body uses at complete rest to maintain basic functions — breathing, circulation, cell production. It is typically 60–70% of total daily energy use.
Which formula is this?
Mifflin-St Jeor, which generally outperforms the older Harris-Benedict equation.
How accurate is it?
Within about 10% for most people. Body composition matters — two people of identical height and weight can differ if one carries more muscle.
Is this calculator free?
Yes, with no account, no limits and no data collection. It runs entirely in your browser.
Should I rely on this for a financial or medical decision?
No. It is a planning estimate built on standard formulas and stated assumptions. For decisions that matter, speak to a qualified professional who can account for your full circumstances.
Is this calculator accurate?
The arithmetic is exact — it uses the standard formula. What limits accuracy is the assumptions: the figures you enter, and factors the formula does not model such as fees, taxes and rule changes.
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Nothing is sent anywhere. The figures you type stay in this page and are never transmitted or stored — how that works.
Disclaimer. The formula is exact; the answer is only as good as the figures and assumptions above. Not financial, tax, medical or legal advice. Full disclaimer.