Question 1

What is BMR?

Accepted Answer

Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic life-sustaining functions — breathing, circulation, cell production — while completely at rest.

Question 2

What is TDEE?

Accepted Answer

Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor. It represents the total calories you burn in a day, including movement and exercise.

Question 3

What is RMR and how is it different from BMR?

Accepted Answer

Resting Metabolic Rate (RMR) is measured under less strict lab conditions than BMR and is typically 3-10% higher because it includes minor movement and digestion effects.

Question 4

What is the most accurate BMR formula?

Accepted Answer

The Mifflin-St Jeor equation is generally considered the most accurate for the general population. Katch-McArdle is more precise for lean, athletic individuals since it uses body fat percentage.

Question 5

How do I use BMR for weight loss?

Accepted Answer

Calculate your TDEE, then eat 250-750 calories below it depending on how aggressive you want your deficit to be, aiming for roughly 0.25-0.75 kg (0.5-1.5 lb) of loss per week.

Question 6

How many calories should I cut to lose 1 pound a week?

Accepted Answer

A pound of body fat is roughly 3,500 calories, so a daily deficit of about 500 calories below TDEE produces roughly 1 pound (0.45 kg) of loss per week.

Question 7

Why do men usually have a higher BMR than women?

Accepted Answer

Men typically carry more lean muscle mass and less body fat than women at the same weight, and muscle tissue burns more calories at rest than fat tissue.

Question 8

How accurate are BMR calculators?

Accepted Answer

Formula-based BMR calculators are estimates and can differ from a lab-measured value by around 10%. Indirect calorimetry is the most accurate way to measure BMR directly.

Question 9

Should I eat only my BMR in calories?

Accepted Answer

No. BMR only reflects resting needs. Eating at or below BMR for a sustained period can slow your metabolism and isn't recommended without medical supervision.

Question 10

Does age affect BMR?

Accepted Answer

Yes. BMR tends to decline with age, largely due to the gradual loss of muscle mass, so calorie needs typically decrease over time unless activity or muscle mass increases.

Question 11

Can I use this calculator for muscle gain?

Accepted Answer

Yes. Add roughly 250-500 calories above your TDEE to create a surplus that supports muscle growth while limiting excess fat gain.

Question 12

How often should I recalculate my BMR?

Accepted Answer

Recalculate every 4-8 weeks or whenever your weight changes by more than a few kilograms/pounds, since BMR shifts as body weight and composition change.

Question 13

Does this calculator support body fat percentage?

Accepted Answer

Yes. Selecting the Katch-McArdle formula reveals a body fat percentage field, which uses lean body mass for a more precise estimate in leaner individuals.

Question 14

What's the difference between Mifflin-St Jeor and Harris-Benedict?

Accepted Answer

Harris-Benedict is an older 1919 equation (revised in 1984) that tends to overestimate BMR slightly compared to the more modern and widely validated Mifflin-St Jeor equation.

Question 15

What is Katch-McArdle and when should I use it?

Accepted Answer

Katch-McArdle calculates BMR from lean body mass rather than total weight, making it more accurate for athletic or very lean individuals who know their body fat percentage.

Question 16

How does activity level affect my calorie needs?

Accepted Answer

Activity level scales your BMR up to your TDEE. Moving from sedentary to very active can raise daily calorie needs by several hundred to over a thousand calories.

Question 17

What factors affect BMR besides age and weight?

Accepted Answer

Muscle mass, height, sex, genetics, hormone levels (especially thyroid function), body temperature, and even climate can all influence BMR.

Question 18

Can exercise increase my BMR long-term?

Accepted Answer

Yes, primarily by building lean muscle mass through resistance training, since muscle tissue burns more calories at rest than fat tissue does.

Question 19

Is a higher BMR always better?

Accepted Answer

Not inherently — BMR simply reflects how many calories your body needs at rest. What matters for health and body composition goals is how BMR relates to total intake and activity.

Question 20

How do macros relate to my TDEE?

Accepted Answer

Once you know your daily calorie target from TDEE, macros split that total into protein, carbohydrate, and fat grams based on your goals and preferences.

Question 21

Does BMI factor into the BMR calculation?

Accepted Answer

No, BMI and BMR are calculated independently. BMI is a screening measure of weight relative to height, while BMR estimates resting calorie needs.

Question 22

Can pregnancy or medical conditions affect BMR?

Accepted Answer

Yes. Pregnancy, thyroid disorders, and other medical conditions can significantly raise or lower BMR, so anyone with such conditions should consult a healthcare provider.

Metric	What It Measures	Typical Use
BMR	Calories burned at complete rest, strict lab conditions (post-fast, no movement)	Baseline for calculating TDEE and calorie targets
RMR	Calories burned at rest under less strict conditions; usually 3-10% higher than BMR	Practical, easier-to-measure alternative to BMR
TDEE	Total calories burned per day including all activity	The number to base weight loss, maintenance, or gain targets on

BMR Calculator — BMR, TDEE & RMR (2026)

BMR Formulas & Worked Examples

Mifflin-St Jeor (Most Accurate for Most People)

Harris-Benedict (Revised 1984)

Katch-McArdle (Best for Lean/Athletic Individuals)

TDEE = BMR × Activity Multiplier

BMR vs TDEE vs RMR — What's the Difference?

Factors That Affect Your BMR

How to Increase Your Metabolism

Related Calculators

Scientific References

BMR Calculator — Frequently Asked Questions