BMR Calculator

Calories you burn by existing. Finally, a skill you already have.

Use this free BMR calculator to estimate your Basal Metabolic Rate — the calories your body burns at complete rest just to keep the lights on: breathing, pumping blood, regulating temperature, and processing the questionable decisions from last night.

BMR is the floor under every calorie number you will ever see. Your TDEE is built on top of it, your deficit is measured against it, and your "why am I so tired" is often explained by eating below it. We use the Mifflin–St Jeor equation, the current standard in clinical nutrition.

What This BMR Calculator Does

Calculates BMR in kcal/day from weight (lb), height (in), and age
Uses Mifflin–St Jeor, the equation with the best accuracy record for adults
Gives you the base for TDEE, calorie targets, and macro splits
Explains the male/female constant so you can adjust honestly

How to Use the BMR Calculator

Inputs:

Weight — pounds (kg × 2.205)
Height — inches (cm ÷ 2.54)
Age — years

Steps:

Enter your three numbers
Click Calculate
Female? Subtract 166 kcal from the result (see formula notes)
Multiply by an activity factor (1.2–1.9) to get your daily burn, or jump to the TDEE calculator

How the Calculation Works

Men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5 Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161

This calculator applies the male constant (+5); the female version is 166 kcal lower
Weight contributes the most, height second, age subtracts about 5 kcal per year — yes, birthdays cost calories
BMR is measured lying down, fasted, in a neutral-temperature room. Nobody lives like that, which is why TDEE exists

Worked Example: 150 lb, 5'5", 30 years old (female)

150 lb ÷ 2.2 = 68.2 kg · 65 in × 2.54 = 165.1 cm
Calculator (male constant): 10 × 68.2 + 6.25 × 165.1 − 5 × 30 + 5 = 682 + 1,032 − 150 + 5 = 1,569 kcal
Female adjustment: 1,569 − 166 = 1,403 kcal/day at rest
Sedentary TDEE ≈ 1,403 × 1.2 = 1,684 kcal. The number your body spends doing absolutely nothing is bigger than most people's crash diets. Think about that.

Frequently Asked Questions

What is a normal BMR?

Most adults land between 1,200 and 2,000 kcal/day. Bigger, younger, and more muscular bodies burn more at rest; smaller, older, and less muscular ones burn less.

Should I eat below my BMR to lose weight?

Generally no. Eat below your TDEE, not your BMR. Sustained intake under BMR tends to cost muscle, energy, and sanity, and the weight loss rarely sticks.

How can I raise my BMR?

Build muscle — it burns more at rest than fat. Sleep enough, eat adequate protein, and stop doing 800-calorie days, which teach your body to run cheaper. There is no tea for this.

Why does the calculator use the male formula?

To keep the inputs to three fields. The only difference is the constant: subtract 166 kcal for the female equation. Everything else is identical.

BMR vs RMR — same thing?

Nearly. RMR (resting metabolic rate) is measured under slightly looser conditions and runs ~10% higher. Online calculators, including this one, use the terms almost interchangeably.

Mini Roast Disclaimer

We roast the number, not you. Burning 1,500 calories while doing nothing is genuinely impressive. Doing nothing was never the problem.

Reality Check

Prediction equations are accurate to roughly ±10% for most people and worse for the very lean, very heavy, or very athletic. Thyroid conditions, medications, and dieting history all shift the real number. If precision matters, indirect calorimetry at a clinic measures it directly.

BMR Calculator (Basal Metabolic Rate)

Inputs