Basal Metabolic Rate (BMR) is calculated with the Mifflin–St Jeor equation, the standard adopted by the American Dietetic Association in 2005 because it outperformed older formulas (Harris–Benedict, Katch–McArdle) on accuracy. Total Daily Energy Expenditure (TDEE) multiplies BMR by an activity factor — sedentary 1.2, light 1.375, moderate 1.55, active 1.725, very active 1.9. The numbers are estimates; individual variation is ±10–15%.


              male:   BMR = 10·kg + 6.25·cm − 5·age + 5
female: BMR = 10·kg + 6.25·cm − 5·age − 161
TDEE = BMR × activity_factor

Common use cases

Setting a baseline calorie target before starting a fat-loss or muscle-gain plan.
Sanity-checking the TDEE estimate from a fitness tracker.
Comparing how much your daily burn changes across different activity levels.

Frequently asked questions

Is Mifflin–St Jeor better than Harris–Benedict?

On average yes, by ~5%. It was published in 1990 using a more diverse and modern population sample. The American Dietetic Association recommends it as the default.

Why are the activity multipliers so wide?

They lump together NEAT (fidgeting, walking around) and exercise. Pick the level that matches your typical week, not your best week.

Should I eat my BMR?

No — eat at or above TDEE for maintenance. Eating only BMR is too aggressive a deficit and unsustainable.

Does it account for body composition?

No — the formula uses height/weight only. For lean athletes, Katch–McArdle (which uses lean body mass) is more accurate.

Embed this tool

Add this free calorie calculator to your own website or blog — copy the code below and paste it into your page HTML. No signup, no API key.

<iframe src="https://otoolrun.com/embed/calorie-calculator/" width="100%" height="560" style="border:0;border-radius:12px" loading="lazy" title="Calorie Calculator"></iframe>
<p style="font-size:14px"><a href="https://otoolrun.com/tools/calorie-calculator/">Calorie Calculator by oToolRun</a></p>

🔥 Calorie Calculator

Related Tools

0 comments

How it works