Basal Metabolic Rate across three evidence-based formulas, with total daily calories — 100% private.
All BMR formulas are statistical estimates and vary by body composition and genetics. Use the value as a starting point for planning — not as medical or dietary advice. Consult a professional for personalized guidance.
BMR (basal metabolic rate) is the calories your body burns at complete rest — just keeping you alive. Multiplying it by an activity factor gives your daily maintenance calories. The three formulas differ mainly in how they weigh muscle vs. overall mass.
The best-supported formula for the general population; it is what most dietitians and modern apps use by default.
The older classic; tends to run slightly higher than Mifflin for most people.
The most accurate when you know your body-fat %. It uses lean mass directly, so athletes typically see higher values. Enter a body-fat % in the calculator to enable it.
| Activity level | Factor | Daily calories |
|---|---|---|
| Sedentary | × 1.2 | 1,644 kcal |
| Lightly active | × 1.375 | 1,884 kcal |
| Moderately active | × 1.55 | 2,124 kcal |
| Very active | × 1.725 | 2,363 kcal |
| Extra active | × 1.9 | 2,603 kcal |
Maintenance = BMR × factor. Eat less to lose, more to gain — adjust in small (~200 kcal) steps.
Sample person: female, 30, 165 cm, 65 kg, ~24% body fat.
Calculate your basal metabolic rate with three evidence-based formulas — Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle — plus daily calories across 5 activity levels. Everything runs locally; nothing is uploaded.
FreeToolHub BMR Calculator is a free browser-based tool — calculate your basal metabolic rate with three evidence-based formulas — Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle — plus daily calories across 5 activity levels. No signup, no upload; everything runs locally in your browser.
Calculate your basal metabolic rate with three evidence-based formulas — Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle — plus daily calories across 5 activity levels. 100% private.
This calculator estimates your Basal Metabolic Rate (BMR) — the calories your body burns just to stay alive at rest — using three evidence-based formulas side by side: Mifflin-St Jeor (1990), the revised Harris-Benedict (1984), and Katch-McArdle, which requires body-fat percentage and uses lean body mass directly. From that baseline it derives your total daily energy expenditure (TDEE) across five activity levels, so you can see how many calories maintain your weight at each lifestyle. Because the formulas disagree slightly, comparing all three gives you a realistic range rather than a single false-precision number.
(1) Enter your sex, age, weight in kilograms, and height in centimeters. (2) Optionally enter body-fat percentage — when known, the Katch-McArdle formula activates and gives the leanest-body prediction. (3) Multiply your BMR (Mifflin by default) by activity factors from sedentary (1.2) to extra active (1.9) to get daily maintenance calories. (4) To lose weight, eat slightly below the number for your activity level; to gain, slightly above — adjusting in ~200-kcal steps and reassessing over a few weeks. All data is computed locally in your browser.
A practical rule: trust Mifflin-St Jeor as your baseline, and treat the other two as a confidence band. If the three estimates sit within 50–100 kcal of each other, use the middle. When they diverge more, the reason is usually body composition — a high Katch-McArdle relative to Mifflin signals above-average lean mass, so favor Katch-McArdle; the reverse suggests the height-weight formulas are overestimating for you, so plan against the lower number. The estimates themselves carry a real uncertainty of roughly ±10% even under the best formula, which is why the calculator also shows the five activity-scaled targets: watching how your weight responds to a given intake over 2–3 weeks tells you more than any formula can. The tool accepts metric (kg/cm) and imperial (lb/ft-in) inputs, converts internally, and can save profiles in your browser so couples or clients can compare side by side.
BMR is the calories you burn at complete rest. TDEE (total daily energy expenditure) multiplies BMR by an activity factor and is the true maintenance number. The calculator shows both.
For the general population, Mifflin-St Jeor (1990) is the best-supported and is the default in most modern apps. Katch-McArdle is more accurate for athletes because it uses lean body mass.
A safe deficit is roughly 300–500 calories below your maintenance level, which generally produces about 0.5–1 lb (0.2–0.5 kg) of loss per week. Never drop too low — consult a professional.
A lean bulk starts 200–300 calories above maintenance, paired with resistance training. Faster surpluses add fat faster than muscle; expect roughly 1–2 lb of muscle per month at best as a beginner, slower as you advance.
Height-weight formulas overestimate for high body-fat percentages and underestimate for very muscular builds, because they cannot see composition. If you know your body-fat %, use the Katch-McArdle result — it scales with lean mass and is far closer in both cases.
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