BMR Calculator
Use the Mifflin-St Jeor equation to estimate basal metabolic rate, the energy your body needs to keep functioning at rest.
Basal metabolic rate
1,699 kcal
Per day at complete rest · Mifflin-St Jeor
Sedentary daily needs
2,039 kcal
Moderately active
2,633 kcal
- Sedentary (little exercise)
- 2,039 kcal
- Light exercise (1–3 days)
- 2,336 kcal
- Moderate exercise (3–5 days)
- 2,633 kcal
- Very active (6–7 days)
- 2,930 kcal
- Athlete / physical job
- 3,228 kcal
- Same inputs with the other equation
- 1,763 kcal
How this was calculated
- 1.Mifflin-St Jeor: 10 × 75 + 6.25 × 175 − 5 × 30 + 5
- 2.BMR = 1,699 kcal per day.
- 3.Multiply by an activity factor (1.2 to 1.9) to estimate total daily energy expenditure.
BMR is measured at complete rest. Real daily needs are higher by the activity multiplier shown in the table.
How the bmr calculation works
Basal metabolic rate is the energy your body uses just to stay alive: breathing, circulation, cell repair and temperature control. It typically accounts for 60–70% of the calories a sedentary person burns.
The Mifflin-St Jeor equation is the modern standard, more accurate than the older Harris-Benedict formula for most people. Harris-Benedict is still used in clinical settings and is shown for comparison.
Multiply BMR by an activity factor to get total daily energy expenditure. This is the number to build a calorie target on — not the BMR itself.
Worked example
A 30-year-old man, 75 kg, 175 cm.
- →10 × 75 = 750
- →6.25 × 175 = 1,093.75
- →5 × 30 = 150
- →750 + 1,093.75 − 150 + 5
Answer: About 1,699 kcal a day at rest, or 2,039 kcal with light activity.
BMR FAQs
Should I eat my BMR?
Generally not — BMR is what you burn lying still. Eating only your BMR means a very aggressive deficit. Base your intake on total daily expenditure instead.
Why does BMR fall as I age?
Mainly because muscle mass declines. Resistance training preserves lean mass, which keeps resting energy expenditure higher for longer.
How accurate are these equations?
Within roughly 10% for most people, but individual variation is real. Track your weight over two to three weeks and adjust: the scale is the better predictor.
BMR Calculator is part of the health calculators collection on Calcora, alongside 7 other tools. Results are calculated in your browser and are for information only — see our disclaimer.
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