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BMR Calculator

Estimate basal metabolic rate with Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle and map it to activity levels.

Your details

Enter your measurements to estimate basal metabolic rate.

Optional — enables Katch-McArdle formula

Your estimated BMR

1,649kcal/day

Using Mifflin-St Jeor

TDEE · Moderately active

2,556 kcal/day

Formula comparison

Compare BMR across all available equations

TDEE by activity level

Tap a bar or pill to set your activity level

Energy breakdown

BMR vs calories from daily activity

  • Basal (BMR)

    1,649 kcal (65%)

  • Activity

    907 kcal (35%)

  • Total TDEE: 2,556 kcal

Estimate only — not medical advice

BMR and TDEE results are formula-based estimates. Individual metabolism varies. Consult a healthcare professional before making dietary changes.

BMR1,649kcal
TDEE · Moderately active2,556 kcal

Mifflin-St Jeor

MSJH-B

How it works

Basal metabolic rate (BMR) estimates how much energy your body uses for essential functions at rest—breathing, circulation, cellular repair—before adding exercise and daily movement.

Calcuit supports common adult formulas such as Mifflin-St Jeor and revised Harris-Benedict, and Katch-McArdle when you have a body-fat estimate. Different equations can disagree by a noticeable margin.

Enter sex, age, height, and weight (and body fat if you use Katch-McArdle). Compare formula outputs, then optionally map a selected BMR to activity multipliers for a rough daily total.

BMR is not a diet prescription. It is a starting point for maintenance estimates. Illness, hormones, medications, and measurement error all move real metabolism.

For a full-day burn estimate, continue with the TDEE or Calorie calculators. For composition context, see Body Fat and BMI tools.

Frequently asked questions

Which BMR formula should I choose?
Mifflin-St Jeor is widely used for general adult estimates. Harris-Benedict is an older alternative. Katch-McArdle can help when you trust a body-fat percentage. Comparing a few outputs shows uncertainty.
Is BMR the same as RMR?
They are related. BMR is a stricter resting concept; RMR (resting metabolic rate) is similar but measured under less strict conditions. Consumer calculators often use the terms loosely.
Why is my BMR different from a wearable’s estimate?
Wearables and apps use their own models and sensors. Expect disagreement. Use ranges and trends rather than a single exact calorie number.
Can I raise my BMR?
Muscle mass and overall body size influence resting burn. Strength training and avoiding extreme crash diets are common practical levers; genetics still set a large part of the baseline.

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