BMR Formula Comparison Calculator
Compare Mifflin-St Jeor, Harris-Benedict and Katch-McArdle.
Enter your values
Choose one of: Male, Female.
Enter the weight in kg.
Enter the height in cm.
Enter the age in years.
Enter the body fat in %.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Mifflin-St Jeor
- 1,768 kcal
- Harris-Benedict (revised)
- 1,844 kcal
- Katch-McArdle
- 1,752 kcal
- Average of three
- 1,788 kcal
Quick answer
The three common BMR formulas usually agree within a few percent, with Katch-McArdle needing body fat percentage.
Mifflin-St Jeor, revised Harris-Benedict, Katch-McArdle (370 + 21.6 x lean mass)
At a glance
| What it does | Compare Mifflin-St Jeor, Harris-Benedict and Katch-McArdle. |
|---|---|
| Category | Health |
| Inputs needed | Sex, Weight, Height, Age, Body fat |
| Main output | Mifflin-St Jeor |
| Formula | Mifflin-St Jeor, revised Harris-Benedict, Katch-McArdle (370 + 21.6 x lean mass) |
| Cost | Free — no sign-up, no download |
How to use the BMR Formula Comparison Calculator
- 1Enter your stats — body fat is only needed for the Katch-McArdle estimate.
- 2Mifflin-St Jeor is generally considered the most accurate for the general population.
- 3Use the same formula consistently over time so your comparisons stay meaningful.
Inputs explained
- Sex
- Choose one of: Male, Female.
- Weight(kg)
- Enter the weight in kg.
- Height(cm)
- Enter the height in cm.
- Age(years)
- Enter the age in years.
- Body fat(%)
- Enter the body fat in %.
Worked example
Using the values the calculator loads with:
Inputs
- SexMale
- Weight80 kg
- Height178 cm
- Age30 years
- Body fat20 %
Results
- Mifflin-St Jeor1,768 kcal
- Harris-Benedict (revised)1,844 kcal
- Katch-McArdle1,752 kcal
- Average of three1,788 kcal
Frequently asked questions
Why do formulas disagree?
They were derived from different study populations, so equations weight height, weight and age differently.
Which should I trust?
Mifflin-St Jeor is the modern default; Katch-McArdle can be more accurate if you know your body fat precisely.
What do I need to enter into the BMR Formula Comparison Calculator?
Just 5 values: sex, weight, height, age, body fat. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the BMR Formula Comparison Calculator work out the answer?
The three common BMR formulas usually agree within a few percent, with Katch-McArdle needing body fat percentage. It applies the formula Mifflin-St Jeor, revised Harris-Benedict, Katch-McArdle (370 + 21.6 x lean mass) and shows the working so you can check each step by hand.
Is the BMR Formula Comparison Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.