BMR & TDEE Calorie Calculator
Estimate your Basal Metabolic Rate with the Mifflin-St Jeor equation, derive your Total Daily Energy Expenditure from your activity level, and see cutting and bulking calorie targets instantly.
Energy Balance Inputs
Your Calorie Targets
BMR
—
kcal/day at complete rest
TDEE
—
kcal/day to hold weight
Cutting (−20%)
—
kcal/day for fat loss
Bulking (+10%)
—
kcal/day for muscle gain
Formula Breakdown
Waiting for input…
Educational estimate only — this calculator applies a population formula and is not personalized medical advice. Consult a qualified healthcare professional before making significant diet changes.
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The Math Behind Your Metabolism
Understand the Mifflin-St Jeor equation, activity multipliers, and the calorie targets derived from them.
How The Formula Works
Basal Metabolic Rate (BMR) is the energy your body burns at
complete rest just to stay alive — breathing, circulation, and
cell repair. This page uses the
Mifflin-St Jeor equation, the most widely
validated resting metabolism formula. For men:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age +
5. For women:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age −
161. Total Daily Energy Expenditure (TDEE) multiplies BMR by an
activity factor that estimates the energy spent on movement,
digestion, and exercise:
TDEE = BMR × activity factor.
Activity Multiplier Reference
The activity factor models how much you move on top of your resting metabolism:
| Level | Factor | Example |
|---|---|---|
| Sedentary | 1.2 | Desk job, no exercise |
| Light | 1.375 | Exercise 1–3 days/week |
| Moderate | 1.55 | Exercise 3–5 days/week |
| Very active | 1.725 | Hard exercise 6–7 days/week |
| Athlete | 1.9 | Twice-daily hard training |
Troubleshooting & Edge-Case Failure Points
- Unit conversion errors: pounds must be divided by 2.20462 to become kilograms, and feet/inches converted to centimetres (1 inch = 2.54 cm). One wrong unit can shift the result by hundreds of calories.
- Formula validation range: Mifflin-St Jeor was validated primarily for adults aged roughly 18–80. Extreme ages, very high lean mass, or significant obesity reduce the formula's accuracy.
- Activity overestimation: most people overstate how active they are. A "moderately active" person who actually exercises twice a week may see weight loss slower than expected.
- Daily fluctuation: your true metabolism varies with sleep, stress, and temperature; a single figure is a starting point, not a law.
- Body recomposition: as you lose weight, your BMR falls because there is less body mass to maintain — recompute after every 5–10 kg (10–20 lb) change.
Step-by-Step Instructions
- Select your biological sex — this decides which constant ( +5 or −161 ) the Mifflin-St Jeor equation applies.
- Enter your age in years and your current weight, choosing kilograms or pounds.
- Enter your height in centimetres or feet and inches — the page converts automatically.
- Pick the activity level that honestly matches an average week, not your best week.
- Click "Calculate" and read BMR, TDEE, the cutting target (−20% of TDEE) for fat loss, and the bulking target (+10% of TDEE) for muscle gain.
- Use the Copy button to save your numbers, and recompute whenever your weight changes materially.
Related Web Utilities (Silo Hub)
Informative Guides & Helper Articles
Best Practices for BMR & TDEE Calculation
Getting accurate inputs, choosing an honest activity multiplier, and turning a calorie estimate into a sustainable nutrition plan.
Read Article →Common Errors in BMR & TDEE Calculation
Unit conversion slips, overestimated activity, treating the estimate as gospel, and the mistakes that silently inflate or cut your target.
Read Article →Top Optimization Tips for BMR & TDEE
Recomputing after weight changes, hitting protein targets, and adapting your calorie budget to how your body actually responds.
Read Article →Future Trends in BMR & TDEE Estimation
Wearable metabolic tracking, AI nutrition coaching, and the shift from population formulas to individualized energy balance.
Read Article →How to Use the BMR & TDEE Calorie Calculator
Computes basal metabolic rate (Mifflin-St Jeor) and total daily energy expenditure — the honest starting line for any fat-loss or muscle-gain plan.
- Enter weight, height, age, and sex — Mifflin-St Jeor is the research-standard equation.
- Pick an activity multiplier honestly (most desk workers are 1.3–1.5, not 1.7).
- Read TDEE, then apply the planning rule: −15–20% to lose, +5–10% to gain.
Mifflin-St Jeor and the Multiplier Table
BMR: men = 10W + 6.25H − 5A + 5; women = 10W + 6.25H − 5A − 161. Worked example: 80 kg, 180 cm, 30-year-old male → 800 + 1125 − 150 + 5 = 1,780 kcal before activity. Multipliers: sedentary 1.2, light 1.375, moderate 1.55, very active 1.725 → this example at office-job-light = ~2,450 kcal TDEE. Reality checks most plans need: trackers and gym machines overestimate exercise burn 15–40%; the multiplier is where the error lives, so derive yours from 2–3 weeks of real weight data instead (if weight is stable eating 2,600, your TDEE is 2,600). Deficits beyond ~25% cost muscle and adherence, which is why −500 kcal/day (≈0.45 kg/week) remains the classic sustainable ceiling.
BMR & TDEE Calorie Calculator FAQ
Which BMR equation is most accurate?
Mifflin-St Jeor beats Harris-Benedict for the general population per ADA position papers; even so, individual error runs +/-10% - calibrate with real weight data.
How many calories should I cut to lose weight?
15-20% below TDEE (commonly ~500 kcal/day, about 0.5 kg/week). Steeper cuts lose muscle and adherence.
Is TDEE the same as maintenance calories?
Yes - and your empirically observed maintenance (stable weight over 2-3 weeks) is worth more than any calculator estimate.