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Your basal metabolic rate (BMR) is the number of calories your body burns at complete rest, just to keep you alive — breathing, circulating blood, running your organs. It's the foundation of any calorie plan: your total daily needs are simply your BMR scaled up by how active you are. Knowing it tells you the minimum energy your body requires before any movement.
Enter your sex, age, weight and height, and your BMR is calculated instantly.
BMR Calculator: step-by-step worked example
- Sex
- Male
- Age
- 35
- Weight (kg)
- 80
- Height (cm)
- 178
- Formula
- Mifflin-St Jeor (recommended)
- 1
Weight term
10 × Weight (kg)
10 × 80 = 800 kcal
- 2
Height term
6.25 × Height (cm)
6.25 × 178 = 1,112.5 kcal
- 3
Age term
5 × Age
5 × 35 = 175 kcal
- 4
BMR with Mifflin-St Jeor
BMR = 10×kg + 6.25×cm − 5×age + (male +5 / female −161)
800 + 1,112.5 − 175 + 5 = 1,743 kcal
- 5
Cross-check: Harris-Benedict (revised)
Male: 88.362 + 13.397×kg + 4.799×cm − 5.677×age · Female: 447.593 + 9.247×kg + 3.098×cm − 4.330×age
= 1,816 kcal
- 10 × weight800 kcal
- 6.25 × height+1,112.5 kcal
- 5 × age−175 kcal
- Male constant+5 kcal
- BMR1,742.5 kcal
- Mifflin-St Jeor1,743 kcal
- Harris-Benedict1,816 kcal
Good to know: Mifflin-St Jeor (1990) is considered one of the most accurate equations for healthy adults, yet individual error can reach ±10%. BMR is energy at complete rest — multiply by an activity factor for daily needs. Thyroid disease, pregnancy or medication can skew it.
BMR Calculator — how it works
Formulas
The tool offers the two most established equations:
Mifflin-St Jeor (recommended, more accurate today): - Men: 10 × kg + 6.25 × cm − 5 × age + 5 - Women: 10 × kg + 6.25 × cm − 5 × age − 161
Harris-Benedict (revised, older standard): - Men: 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age - Women: 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age
BMR is not your daily calorie need
BMR is what you burn doing nothing. Your actual daily requirement is BMR multiplied by an activity factor (1.2 for sedentary up to 1.9 for very active). Never eat only your BMR to lose weight faster — it's below your body's real needs and isn't sustainable. For the full figure use a calorie calculator.
What affects BMR
- Muscle mass: muscle burns more at rest than fat, so a leaner body has a higher BMR.
- Age: BMR gradually declines with age as muscle mass falls.
- Size: taller, heavier people have a higher BMR.
- Sex: at the same size, men usually have a higher BMR due to more muscle.
Worked example
A 30-year-old man, 180 cm tall, weighing 82 kg: with Mifflin-St Jeor, BMR = 10×82 + 6.25×180 − 5×30 + 5 = 820 + 1,125 − 150 + 5 = 1,800 kcal. With the older Harris-Benedict equation the same person comes out around 1,880 kcal — a difference of about 80 kcal that shows why the formula matters. To get his real daily need, multiply the BMR by his activity factor: moderately active (1.55) gives 1,800 × 1.55 = 2,790 kcal.
Basal metabolic rate by weight (Mifflin-St Jeor, age 30)
Assumes 175 cm for men and 165 cm for women. Each 10 years of age lowers BMR by about 50 kcal; each 10 cm of height adds about 62 kcal.
| Weight | Men (175 cm) | Women (165 cm) |
|---|---|---|
| 50 kg | 1,449 kcal | 1,220 kcal |
| 60 kg | 1,549 kcal | 1,320 kcal |
| 70 kg | 1,649 kcal | 1,420 kcal |
| 80 kg | 1,749 kcal | 1,520 kcal |
| 90 kg | 1,849 kcal | 1,620 kcal |
| 100 kg | 1,949 kcal | 1,720 kcal |
| 110 kg | 2,049 kcal | 1,820 kcal |
| 120 kg | 2,149 kcal | 1,920 kcal |
Frequently asked questions
How is BMR calculated?+
With an equation using your weight, height, age and sex. The recommended Mifflin-St Jeor formula gives, for a 30-year-old 180 cm 82 kg man, 10×82 + 6.25×180 − 5×30 + 5 = 1,800 kcal.
What is the difference between Mifflin-St Jeor and Harris-Benedict?+
Both estimate BMR; Mifflin-St Jeor is newer and generally more accurate for modern populations, while Harris-Benedict is the older standard. Results differ by around 5%.
Should I eat only my BMR to lose weight?+
No — BMR is what you burn at rest, below your real daily needs. Eating at BMR is too aggressive and costs muscle. Aim for a modest deficit below your total daily needs instead.
How do I turn BMR into my daily calorie need?+
Multiply BMR by an activity factor: 1.2 (sedentary) to 1.9 (very active). A calorie calculator does this and gives loss and gain targets too.
Why does BMR decline with age?+
BMR falls mainly because muscle mass decreases with age, and muscle burns more calories at rest than fat. Staying active and maintaining muscle slows the decline.
Why do men and women have different BMRs?+
At the same height, weight and age, men usually have more muscle mass, which raises resting energy use. The formulas reflect this with a different constant for each sex.
Sources
About this page
- Publisher:
- Kalkoro — Teknolojig Bilişim Teknolojileri A.Ş., İstanbul
- Written by:
- Kübra Yıldız — Editor (Health, nutrition, pregnancy, education, exam scores)
- Reviewed by:
- Furkan Tur — Editor
Parameters come from official sources; the last update date is shown at the bottom of the page.
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How we calculate and our accuracy policy →
This tool is for general information only and is not medical diagnosis, treatment or advice. Consult a physician for decisions about your health.
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