BMI vs BMR Comparison Calculator
Two health numbers often get mixed up: BMI (body mass index) measures your weight relative to your height, while BMR (basal metabolic rate) measures how many calories your body burns at complete rest. Enter your details below to see both side by side, plus your total daily energy expenditure (TDEE). All calculations happen in your browser — nothing is uploaded.
Enter your details
BMI — Body Mass Index
–
–
Measures your weight relative to your height. Formula: weight (kg) ÷ height (m)2. Categories follow the WHO scale.
BMR — Basal Metabolic Rate
– kcal/day
–
Measures the calories your body burns at complete rest, calculated with the Mifflin-St Jeor equation.
Comparison table: BMI vs BMR
| Aspect | BMI | BMR |
|---|---|---|
| What it measures | Weight relative to height — a rough screen for body size | Calories burned at rest — your baseline energy use |
| Inputs needed | Height and weight only | Height, weight, age and sex |
| Unit | kg/m² (a number) | Kilocalories per day |
| Used for | Classifying underweight, healthy, overweight or obesity ranges | Planning daily calorie intake and weight goals |
| Tells you about exercise? | No | No — combine with activity level to get TDEE |
| Limitations | Cannot tell muscle from fat; misleading for athletes | An estimate — real burn varies with body composition and health |
Your daily calorie targets (TDEE)
TDEE = BMR × activity factor. It estimates the total calories you burn in a day including movement and exercise.
| Goal | Calories per day | Meaning |
|---|
How to use
- Enter your height, weight, age and sex, then choose the activity level closest to your week.
- Press Calculate to see your BMI with its WHO category and your BMR in kcal/day.
- Read the comparison table to understand how the two numbers differ.
- Use the TDEE targets as rough guides for maintaining, losing or gaining weight.
Please note: these numbers are estimates based on population formulas, not a medical diagnosis. BMI cannot tell muscle from fat, and BMR is an approximation. Talk to a doctor or registered dietitian before making major diet or exercise changes.
Frequently asked questions
BMI is a number describing your weight relative to your height, used to screen for underweight, healthy weight, overweight or obesity ranges. BMR is the number of calories your body burns at complete rest each day. BMI tells you about body size; BMR tells you about baseline energy use.
This tool uses the Mifflin-St Jeor equation: for men, 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5; for women, the same with − 161 instead of + 5. It is widely considered the most accurate general BMR formula.
TDEE (total daily energy expenditure) is your BMR multiplied by an activity factor. BMR only covers complete rest, but you move, work and exercise — TDEE estimates your real total burn, so it is the number to compare against your food intake for weight goals.
BMI only uses height and weight, so it cannot tell muscle from fat. Athletes, weightlifters and very muscular people can score as overweight while being healthy. It is a screening guide, not a body composition test.
A common guideline is eating about 500 kcal below TDEE for steady weight loss or about 500 kcal above for weight gain. The table above shows those targets from your numbers. These are rough guides — consult a health professional for a personal plan.