# Mifflin–St Jeor Calculator (BMR)

URL: https://speedycalculator.com/calculators/health/bmr/
Last updated: 2026-10-30

> This BMR calculator uses the Mifflin–St Jeor equation – the one recommended by the Academy of Nutrition and Dietetics – to estimate the calories you burn at rest, and converts it into kilojoules and calories per hour.

## Inputs

- Sex
- Age (years)
- Weight (kg, lb, st, g)
- Height (cm, in, m, ft, mm)

## Results

- BMR
- BMR in kilojoules
- Calories per hour at rest
- Daily calories if sedentary (× 1.2)
- Daily calories if moderately active (× 1.55)

## Formula

```
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
```

## Explanation

Mifflin and St Jeor published their equation in 1990 from measurements of 498 healthy adults. In comparisons it predicts measured resting energy expenditure within 10% for more people than older equations.

### How to use the Mifflin–St Jeor Calculator

- **Sex**
- **Age**
- **Weight**
- **Height**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter sex, age, weight and height. The equation adds the effect of weight and height, subtracts the effect of age and applies a constant for sex.

### Inputs explained

FieldWhat to enterSexChoose one: Male, FemaleAgeIn yearsWeightUnits: kg, lb, st, gHeightUnits: cm, in, m, ft, mm

### What each result means

- **BMR in kilojoules** = [BMR]×4.184
- **Calories per hour at rest** = [BMR]÷24
- **Daily calories if sedentary (× 1.2)** = [BMR]×1.2
- **Daily calories if moderately active (× 1.55)** = [BMR]×1.55

### Example values

How the main result changes when **Age** changes and everything else stays at the example values above:

Age (years)BMR (kcal/day)151,79322.51,755301,71837.51,680451,643601,568
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Sex: Male; Age: 30 years; Weight: 75 kg; Height: 178 cm.

Results — **BMR = 1,718 kcal/day**; BMR in kilojoules = 7,186 kJ/day; Calories per hour at rest = 71.6 kcal/h; Daily calories if sedentary (× 1.2) = 2,061 kcal/day; Daily calories if moderately active (× 1.55) = 2,662 kcal/day.

## Key terms

- **BMR**: Basal metabolic rate.

## FAQ

**Is Mifflin–St Jeor better than Harris–Benedict?**
In most studies it is slightly more accurate for modern adults.

**Does BMR include exercise?**
No – it is the energy used at complete rest.

**How can I raise my BMR?**
Building muscle raises it a little; very low calorie diets lower it.


## Sources

- [Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990](https://pubmed.ncbi.nlm.nih.gov/2305711/)
- [Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr, 1984](https://pubmed.ncbi.nlm.nih.gov/6741850/)
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy and Human Performance