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Health & Fitness Calculators

BMR Calculator

Estimate resting energy with the Mifflin-St Jeor equation and transparent assumptions.

Estimate resting energy

Select the original equation set and enter age, weight, and height.

Equation-set labels identify constants from the original study. They do not establish individual metabolic accuracy.

Select an equation set and units, enter all inputs, then calculate.

BMR and resting-energy terminology

The page is commonly called a BMR calculator, but Mifflin and colleagues developed an equation for resting energy expenditure. Basal measurements use stricter laboratory conditions than ordinary resting measurements.

Mifflin-St Jeor equation

10 x kg + 6.25 x cm - 5 x age + 5 (male equation set)

10 x kg + 6.25 x cm - 5 x age - 161 (female equation set)

Worked example

For the male equation set at age 30, 80 kg, and 180 cm: 800 + 1,125 - 150 + 5 = 1,780 kcal/day.

Continue to the Calorie Calculator for a broad activity-based range.

Limitations and common mistakes

  • Do not treat estimated resting energy as measured metabolism.
  • Do not use resting energy alone as a daily intake prescription.
  • Body composition, health, environment, and measurement error can affect actual expenditure.
  • Pregnancy, lactation, childhood, illness, eating disorders, and clinical nutrition require different assessment.

Quick answers

What this calculator answers

  • Result: Estimates resting energy in whole kilocalories per day.
  • Method: Uses one Mifflin-St Jeor equation set with weight, height, and whole-number age.
  • Terminology: The route is commonly called a BMR calculator, but the source equation predicts resting energy expenditure.
  • Limit: An equation estimate is not measured metabolism or a calorie prescription.

Transparency note

Accuracy and limitations

Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.

Health and fitness results are estimates, not medical advice. Formulas simplify real bodies and cycles, so important health decisions should be checked with a qualified clinician.

Reference check

Sources and references

These references provide background context for the topic. They do not replace official advice or documents for personal decisions.

How to Use This Tool

Use these steps to enter the right inputs and interpret the result correctly.

1

Enter the required values in the input fields.

2

The tool will automatically calculate or process the data.

3

Review the results in the result area.

4

Copy or reset the results as needed.

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Frequently Asked Questions

Common questions about BMR Calculator and how to read the result.

Why is this called a BMR calculator?

BMR is common search terminology. The Mifflin-St Jeor paper specifically developed equations for resting energy expenditure, so the result uses that more precise label.

Why are there two equation sets?

The original equation uses different constants for its male and female study groups. Selecting a set does not guarantee individual metabolic accuracy.

Is this a daily calorie target?

No. It estimates resting energy and does not include the full effect of activity or establish an intake recommendation.

Why is age limited to 19 through 78?

Those ages align with the population described in the original Mifflin-St Jeor research.