Calcs4All

APR 23 · 2026

BMR calculator

Estimate basal metabolic rate from weight, height, age, and sex.

What this calculator covers

Use this BMR calculator to estimate how many calories your body might use in a full day at rest before movement, training, or goal adjustments are added.

The calculator keeps the Mifflin-St Jeor inputs and formula visible so the result is easier to audit than a black-box calorie number.

BMR is only a planning estimate. Real energy needs can shift with body composition, medication, illness, and changes in daily routine.

Frequently asked questions

What does BMR measure?
BMR (basal metabolic rate) estimates the calories your body burns over a full day at complete rest — breathing, circulation, and basic cell maintenance only. It does not include any energy spent on movement, digestion, or exercise.
Which formula does this calculator use?
The Mifflin-St Jeor equation, which takes weight, height, age, and biological sex as inputs. It is widely used in dietetics practice because it tends to produce reasonably accurate resting-energy estimates for most adults.
How is BMR different from TDEE?
BMR is the resting baseline. TDEE (total daily energy expenditure) multiplies BMR by an activity factor that accounts for your typical movement and exercise level. Use a TDEE calculator to add that layer on top of the BMR result.
Why does biological sex affect the BMR result?
The Mifflin-St Jeor equation applies a sex-specific constant — a positive value for males and a negative value for females — to reflect average differences in lean mass and resting metabolism between the two groups.

Tool

Run the calculation

years

RESULT · BMR

â„–100

Primary result

1,755 kcal/day

Using the Mifflin-St Jeor equation, a 35-year-old male at 80 kg and 180 cm has an estimated basal metabolic rate of 1,755 kcal/day.

Metric weight used
80 kg
Metric height used
180 cm
Equation variant
Mifflin-St Jeor (male)
Estimated BMR
1,755 kcal/day

Step-by-step solution

  1. 1.Convert the measurement inputs into metric units for the formula: 80 kg and 180 cm.
  2. 2.Apply the Mifflin-St Jeor equation: 10 × 80 + 6.25 × 180 - 5 × 35 + 5.
  3. 3.Round the resting-energy estimate to the nearest calorie for a baseline burn of 1,755 kcal/day.

Walkthrough

Visual walkthrough

BMR estimates the calories your body would use at full rest before activity multipliers or goal adjustments are layered on top.

  1. 01

    Normalize the inputs

    80 kg · 180 cm · 35 years

    The Mifflin-St Jeor equation runs on kilograms, centimeters, age, and a sex-specific constant.

  2. 02

    Run the Mifflin-St Jeor equation

    10w + 6.25h - 5a + 5

    Weight and height increase the estimate, age pulls it down, and the final constant depends on the selected sex.

  3. 03

    Read the resting burn estimate

    This result is the daily energy estimate before exercise, occupation, or intentional gain-loss goals are added.

    1,755 kcal/day