How it works
The BMR calculator estimates resting calorie needs first, then uses activity level to show how BMR becomes TDEE for daily planning.
Resting calorie estimate
BMR Calculator online
Estimate basal metabolic rate, compare BMR formulas, and see how activity turns resting calories into daily energy needs.
Local calculation
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Formula transparent
BMR, TDEE, BMI shown together
Next step ready
Macros, schedule, or explanation
Energy result
Step 2Ready
Your BMR result appears here.
Complete the form to estimate resting calories, activity-adjusted calories, and practical next steps locally in your browser.
Formula explanation
Mifflin-St Jeor is the default BMR formula. Revised Harris-Benedict and Katch-McArdle provide comparison points, but all formula results remain estimates.
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Quick Answers
What does BMR mean?
BMR estimates the calories your body uses at rest for basic functions.
It is a starting estimate, not a precise measurement. Daily calorie planning usually starts by turning BMR into TDEE with an activity multiplier.
Is BMR my daily calorie target?
BMR is usually not your daily calorie target because it does not include activity.
Maintenance calories are usually closer to TDEE. Weight-loss or weight-gain targets should adjust from TDEE rather than using BMR alone.
Mifflin-St Jeor vs Revised Harris-Benedict?
Mifflin-St Jeor is a common modern default, while Revised Harris-Benedict is an older revised population formula.
Both use sex, age, height, and weight. Comparing them helps show that BMR formulas are estimates with a normal range of uncertainty.
When is Katch-McArdle useful?
Katch-McArdle may be useful when you have a reliable body-fat estimate.
It uses lean body mass, so inaccurate body-fat inputs can make the result less useful than a simpler formula.
How does activity level change BMR?
Activity level multiplies BMR to estimate TDEE, which is closer to maintenance calories.
Choosing the right activity level matters because a sedentary multiplier and a very active multiplier can produce very different daily calorie estimates.
Guides
FAQ
What is BMR?
BMR is basal metabolic rate, an estimate of calories your body uses at rest for basic functions.
What formula does this BMR calculator use?
It defaults to Mifflin-St Jeor and also supports Revised Harris-Benedict and Katch-McArdle when body-fat percentage is available.
Is BMR the same as maintenance calories?
No. Maintenance calories are usually closer to TDEE because TDEE includes activity.
Should I eat at my BMR to lose weight?
Not usually. Most plans start from TDEE and then use a moderate deficit, because BMR does not include daily activity.
Which BMR formula is most accurate?
No formula is exact for every person. Mifflin-St Jeor is a common default, while Katch-McArdle can help when body-fat percentage is reliable.
Is this medical advice?
No. BMR results are educational estimates and are not medical advice.