BMR Calculator

Calculate your BMR (Basal Metabolic Rate) — the calories your body burns at rest — using the Mifflin-St Jeor formula.

100% Browser-Based • Local Processing
Units
yr
cm
kg

BMR is what your body burns at complete rest. Your real daily need is higher — multiply by an activity factor, or use the Calorie Calculator. This is an estimate, not medical advice.

Basal metabolic rate

1,780 kcal/day

Per hour 74 kcal
Sedentary (×1.2) 2,136 kcal
Moderate (×1.55) 2,759 kcal
Other formula 1,854 kcal
Formula and working

The formula

BMR = 10 × kg + 6.25 × cm − 5 × age + 5

Your numbers

10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 kcal/day

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Privacy Focused

🔒 Local Processing. Your numbers never leave your device.

Instant Results

🌐 Fully Client-Side. Runs instantly in your browser.

No Signup

⚡ No accounts. No API keys. Just open and use.

Browser Based

🚀 No installs, no sign-ups, no server round-trip.

Overview

What is a BMR Calculator?

A BMR Calculator estimates your Basal Metabolic Rate — the calories your body burns at complete rest just to stay alive. Using the Mifflin-St Jeor equation with your age, sex, height, and weight, it gives your daily resting calorie burn, the baseline for any calorie or weight plan. It runs privately in your browser.

Your Basal Metabolic Rate is the energy your body uses at rest for breathing, circulation, and basic functions — typically the largest part of your daily calorie burn. It's the starting point for working out how many calories you need.

This calculator uses the widely trusted Mifflin-St Jeor equation and shows the formula. It runs entirely in your browser, so your details stay private. To include activity, pair it with the Calorie (TDEE) Calculator.

Guide

How to calculate your BMR

Step 1: Choose metric or imperial units

Choose metric or imperial units.

Step 2: Enter your age, sex, height, and weight

Enter your age, sex, height, and weight.

Step 3: Read your BMR in calories per day, with the formula shown

Read your BMR in calories per day, with the formula shown.

Screens

BMR Calculator in action

BMR Calculator showing basal metabolic rate in the browser.
BMR result
BMR estimated with the Mifflin-St Jeor formula.
Formula
Calculating BMR on a phone, no app installed.
Mobile (stacked)
Details

What BMR means and how it's estimated

BMR is the number of calories your body would burn if you did nothing but rest for 24 hours — it powers involuntary functions like breathing, circulation, and cell repair, and usually accounts for 60–70% of total daily energy use. The calculator uses the Mifflin-St Jeor equation, which research considers one of the most accurate population formulas: for men, BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; for women, the same but − 161. An older alternative, Harris-Benedict, is offered for comparison. These are estimates derived from population averages, so your true BMR can differ based on body composition (more muscle burns more), genetics, hormones, and health conditions — the equations don't measure those directly. BMR is the baseline; your actual daily need is higher because you move, which is captured by multiplying BMR by an activity factor to get TDEE (total daily energy expenditure). Use BMR to understand your resting burn and as the foundation for a calorie target, but treat it as a guide, not a precise medical figure — it isn't medical advice. Everything computes locally in your browser. For calories including activity, use the Calorie Calculator.

Support

Frequently Asked Questions

What is BMR?

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to keep you alive — breathing, circulating blood, repairing cells. It's usually the biggest chunk of your daily calorie use (around 60–70%) and is the baseline before any activity is added.

How is BMR calculated?

This tool uses the Mifflin-St Jeor equation: men, BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; women, the same but − 161. It's regarded as one of the most accurate formulas for estimating resting calorie burn from age, sex, height, and weight. The calculator shows the working.

What's the difference between BMR and TDEE?

BMR is calories burned at rest; TDEE (Total Daily Energy Expenditure) is your full daily burn including movement and exercise. TDEE is BMR multiplied by an activity factor (1.2 for sedentary up to ~1.9 for very active). You use TDEE, not BMR, to set a calorie target — the Calorie Calculator does this.

Which formula is most accurate?

The Mifflin-St Jeor equation (the default here) is widely considered the most accurate general formula for BMR. The older Harris-Benedict equation is also common and is offered as an option. Both are population estimates; neither measures your individual metabolism exactly, which only lab testing can do.

Why might my real BMR differ from the estimate?

Because the formula uses only age, sex, height, and weight, while real metabolism is also affected by body composition (muscle burns more than fat at the same weight), genetics, hormones, and health conditions. Two people with identical stats can have different BMRs, so treat the number as a solid estimate, not an exact measurement.

Can I use BMR to lose or gain weight?

BMR is the foundation: combine it with your activity level to get your TDEE, then eat below TDEE to lose weight or above it to gain. Don't eat below your BMR for long without professional guidance. The calculator gives the baseline; use the Calorie Calculator for a target. It isn't medical advice.

Is it free, and do I need to sign up?

Yes, it's completely free with no account, no trial, and no limit on how many times you use it. It runs entirely in your browser, so there's no sign-in wall — just open the page and calculate.

Is my data private?

Yes. Everything is calculated in your browser — the numbers you enter are never sent to a server, and nothing is stored once you close the tab. That keeps any personal figures (salary, loan, health) on your own device.

Does it work on mobile?

Yes. It runs in your phone's browser with nothing to install, so you can calculate on Android or iOS. The layout adapts to small screens, so entering numbers and reading the result is easy on the go.

Does it work offline?

Once the page has loaded, the calculation runs entirely on your device, so it keeps working without a connection. You only need to be online to open the page the first time — which is also why nothing you enter is uploaded.

Can I copy or share the result?

Yes. You can copy the result to your clipboard with one click, and many results can be shared. Because everything is calculated locally, copying is instant with no upload step.

How accurate is it, and is this professional advice?

The math is accurate for the inputs you give, and the formula is shown so you can verify it. But results are estimates for general use, not professional advice — finance calculators use simplified assumptions and ignore fees and rate changes, and health calculators are general estimates, not medical advice. For important decisions, consult a qualified professional.

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