Purpose and context
What does the BMR Calculator do?
Basal or resting metabolic rate represents energy used to maintain essential functions at rest. Predictive equations provide population-based estimates rather than laboratory measurements.
Who it supports: Adults represented by the published equation categories.
Transparent calculation
Formula and calculation method
Weight is normalized to kilograms and height to centimetres before applying the 1990 Mifflin–St Jeor equation. Calories are rounded to a whole number for display.
Worked calculation example
For a 30-year-old using the male equation at 75 kg and 180 cm: 750 + 1,125 − 150 + 5 = 1,730 kcal/day.
The live calculator retains greater internal precision and rounds only when presenting the result.
How to use the BMR Calculator
- Select the published equation category.
- Enter age, height and weight.
- Calculate resting energy and review the assumptions.
- Use the TDEE calculator when activity needs to be included.
Understanding your result
The result card identifies the value, unit, method, supporting values and an accuracy notice. Estimated and predicted outputs are labelled so that apparent precision is not mistaken for certainty.
Continue with the TDEE Calculator for a related measurement using its own documented method.
Accuracy, assumptions and limitations
Body composition, illness, pregnancy, medications, adaptive metabolism and measurement error can cause actual resting expenditure to differ.
Common input and interpretation mistakes
- Calling predicted BMR a measured laboratory result.
- Using BMR as total daily calorie expenditure.
- Entering mixed units after selecting a unit system.
Primary method source: https://pubmed.ncbi.nlm.nih.gov/2305711/.
Frequently asked questions about BMR Calculator
BMR is the energy used for essential body functions at rest. This calculator predicts it from population data.
Yes. Age is an explicit term in the Mifflin–St Jeor equation and generally lowers the prediction as age increases.
It can affect real resting expenditure, but this general equation does not directly use lean mass.
BMR estimates resting energy; TDEE combines a resting estimate with an activity model.
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