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Free BMR Calculator

Estimate your Basal Metabolic Rate — the calories your body burns at rest — using the widely used Mifflin-St Jeor equation.

Estimated BMR
1,780 kcal/day

Calories burned at rest. Multiply by an activity factor for your total daily needs. General estimate, not medical advice.

Estimate only. This tool is for general information only and is not medical advice or a diagnosis. Results are estimates based on the formula shown. Consult a qualified healthcare professional for guidance about your own situation.

Quick answer

Basal Metabolic Rate (BMR) is the number of calories your body uses at complete rest to keep functioning. The Mifflin-St Jeor formula estimates it as 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 for men, and the same with −161 instead of +5 for women.

Formula & method

Mifflin-St Jeor (men)

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
  • weight — body weight in kilograms
  • height — height in centimeters
  • age — age in years

Mifflin-St Jeor (women)

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Result is calories per day at rest. Multiply by an activity factor for daily needs (TDEE).

Activity factor for TDEE (BMR × factor)

Activity levelMultiply BMR by
Sedentary (little or no exercise)1.2
Lightly active (1–3 days/week)1.375
Moderately active (3–5 days/week)1.55
Very active (6–7 days/week)1.725
Extra active (hard exercise or physical job)1.9

Examples

Example 1: 30-year-old man, 80 kg, 180 cm
Input
male, 80 kg, 180 cm, 30 yr
Result
≈ 1,780 kcal/day
Why
10×80 + 6.25×180 − 5×30 + 5 = 800 + 1125 − 150 + 5 = 1780.
Example 2: 30-year-old woman, 65 kg, 165 cm
Input
female, 65 kg, 165 cm, 30 yr
Result
≈ 1,371 kcal/day
Why
10×65 + 6.25×165 − 5×30 − 161 = 650 + 1031.25 − 150 − 161 = 1370.25.
Example 3: Imperial input
Input
154 lb, 71 in, 30 yr (male)
Result
≈ 1,780 kcal/day
Why
Converted to ~70 kg and ~180 cm, then run through the formula.

When to use this tool

  • Getting a baseline for daily calorie planning.
  • Understanding roughly how many calories you burn at rest.
  • As a starting point before applying an activity multiplier.

Common mistakes

  • Confusing BMR with daily calorie needs. BMR is at-rest only; multiply by an activity factor for TDEE.
  • Entering height in meters instead of centimeters.
  • Treating the estimate as exact. Individual metabolism varies by body composition and genetics.

Frequently asked questions

What is BMR?

Basal Metabolic Rate is the energy, in calories, your body needs at complete rest to maintain vital functions like breathing and circulation.

Which formula does this use?

The Mifflin-St Jeor equation, which is widely regarded as one of the more accurate estimates for most adults.

How is BMR different from TDEE?

BMR is calories at rest. TDEE (total daily energy expenditure) multiplies BMR by an activity factor to include movement and exercise.

Why do men and women have different formulas?

On average, body composition differs, so the equation uses a different constant (+5 for men, −161 for women) to reflect that.

Is this medical advice?

No. It’s a general estimate for information only, not medical or nutritional advice. Consult a professional for personal guidance.

How does age affect BMR?

BMR decreases with age, roughly 2-8% per decade after age 30, because the body loses muscle mass and metabolic efficiency declines. The Mifflin-St Jeor formula accounts for this via the 5×age term.

Why do the formulas differ for men and women?

On average, women have higher body fat and lower muscle mass than men at the same weight and height, so women's baseline metabolic rate is lower. The formula compensates with a different constant (-161 for women vs. +5 for men).

Sources & references

External references open in a new tab. We are independent and not affiliated with these organizations.

Disclaimer

This tool is for general information only and is not medical advice or a diagnosis. Results are estimates based on the formula shown. Consult a qualified healthcare professional for guidance about your own situation.

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  • ✓ Formula and method shown above
Last updated: How we calculateReport a correctionDisclaimer

Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.

Built and reviewed by HIFreeTools against the formula shown above and any authoritative references cited on this page. See our methodology and editorial standards.

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