BMR Calculator — Free Online Tool
Find your Basal Metabolic Rate — calories burned at rest. · No signup · Works on mobile
100% private: your data is processed in your browser. Nothing is uploaded to our servers.
How to use the bmr calculator
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Enter your age, biological sex, height, and weight.
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Pick your typical activity level from sedentary to very active.
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See your BMR plus maintenance calories, and targets for weight loss or gain.
What does this tool do?
This free BMR calculator estimates your Basal Metabolic Rate — the calories your body burns at complete rest just to stay alive. Enter your age, sex, height, and weight to get your BMR via the Mifflin-St Jeor equation, plus daily calorie needs at five activity levels.
How does the bmr calculator work?
It uses the Mifflin-St Jeor equation, the most accurate for the general population per the American Dietetic Association: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 for men, or −161 for women. Daily needs multiply BMR by an activity factor from 1.2 (sedentary) to 1.9 (extremely active).
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR is the energy burned at complete rest; TDEE (Total Daily Energy Expenditure) adds movement, exercise, and digestion. TDEE = BMR × activity factor. A 70 kg moderately active man with a BMR of 1,650 kcal has a TDEE around 2,560 kcal — that's his true maintenance intake.
How many calories should I cut to lose weight?
A deficit of 500 kcal/day below your TDEE produces roughly 0.45 kg (1 lb) of fat loss per week, since 1 lb of fat stores about 3,500 kcal. Never eat below your BMR long-term without medical supervision — aim for a moderate 15–25% deficit instead.
Is the BMR calculator really free?
Yes — 100% free with no hidden charges, trial limits, or premium tiers for core features. You don't need to create an account or enter an email address. The site is supported by non-intrusive display ads, which keeps every tool free for everyone.
Is my data private when using the BMR calculator?
Completely. The BMR calculator runs entirely in your browser using JavaScript — nothing you type or upload is sent to our servers. When you close the tab, your data is gone. This makes it safe for confidential documents, financial figures, and personal information.
Does the BMR calculator work on mobile phones?
Yes. The BMR calculator is built mobile-first and works on any phone or tablet with a modern browser — iPhone (Safari), Android (Chrome), and everything in between. The layout adapts to small screens, so buttons and inputs stay easy to tap on a 375px-wide display.
Do I need to install anything to use the BMR calculator?
No. The BMR calculator works directly in your web browser — no downloads, no extensions, no signup. Just open the page, use the tool, and get your result instantly. It works on Windows, macOS, Linux, ChromeOS, iOS, and Android.