- Mifflin-St Jeor BMR
- 5 levels, 1.2 to 1.9
- Cut, maintain, surplus
Your real daily calorie burn, at all five activity levels
This TDEE and BMR calculator turns your age, height, weight, and activity level into exact numbers: resting metabolism, total daily burn at every activity level, and calorie targets for cutting, maintaining, or gaining.
Get my numbersEnter your age, height, and weight to work out your daily calories.
TDEE reference: BMR formulas, activity multipliers, calorie-goal and macro math
Every daily-energy figure is two numbers stacked: a resting-metabolism estimate, then an activity multiplier applied on top. The tables here hold the raw coefficients, multipliers, and energy-balance math behind both steps, so any calorie target can be reproduced or spot-checked by hand rather than taken on faith.
Resting-metabolism formulas
Three regressions dominate the field. Each returns basal metabolic rate in kcal/day from body metrics in metric units, so pounds and feet convert first.
| Equation | Male form | Female form | Inputs |
|---|---|---|---|
| Mifflin–St Jeor | 10·kg + 6.25·cm − 5·age + 5 | 10·kg + 6.25·cm − 5·age − 161 | weight, height, age, sex |
| Harris–Benedict (Roza–Shizgal revision) | 88.362 + 13.397·kg + 4.799·cm − 5.677·age | 447.593 + 9.247·kg + 3.098·cm − 4.330·age | weight, height, age, sex |
| Katch–McArdle | 370 + 21.6·LBM | 370 + 21.6·LBM | lean body mass only |
Lean body mass for Katch–McArdle is weight_kg × (1 − bodyfat_fraction); a 70 kg body at 20% fat gives an LBM of 56 kg. Sex and age drop out entirely because the term they proxy for, muscle, is now measured directly. The first two formulas need no body-composition input, which is why a four-field calculator defaults to Mifflin–St Jeor.
Activity multipliers
BMR covers rest only. Multiply it by a physical-activity level (PAL) to reach total burn. The standard five-rung ladder:
| Multiplier | Label | A typical week | Applies to |
|---|---|---|---|
| 1.2 | Sedentary | Desk job, little deliberate movement | No structured exercise |
| 1.375 | Lightly active | Light exercise 1–3 days | Short walks, occasional gym |
| 1.55 | Moderately active | Moderate exercise 3–5 days | Consistent training habit |
| 1.725 | Very active | Hard exercise 6–7 days | Daily athletes, physical work |
| 1.9 | Extra active | Hard training plus a physical job | Manual labor, two-a-days |
Pick the rung that matches an ordinary week and count workouts once. Logging exercise separately on top of an active multiplier counts the same session twice and inflates the target.
Calorie and macro targets
Total burn is maintenance. Shift it to change weight, using the energy stored per unit of tissue: roughly 3,500 kcal per pound of body fat, or 7,700 kcal per kilogram.
| Daily adjustment | Weekly change | Note |
|---|---|---|
| −1,000 kcal | ~−2 lb (−0.9 kg) | Aggressive; hard to sustain |
| −500 kcal | ~−1 lb (−0.45 kg) | Standard cutting rate |
| −250 kcal | ~−0.5 lb (−0.23 kg) | Slow, muscle-sparing loss |
| 0 | maintenance | Body-recomposition territory |
| +250 kcal | ~+0.5 lb (+0.23 kg) | Lean bulk pace |
| +500 kcal | ~+1 lb (+0.45 kg) | Faster gain, more fat |
Commonly cited practical floors are about 1,200 kcal/day for women and 1,500 for men; going under for long stretches tends to shed muscle and stall the estimate rather than speed it up. The prediction assumes tissue is fat; early scale drops are mostly water and glycogen, so the rate settles over two to three weeks.
Those goal calories resolve into grams through fixed energy densities. Alcohol is listed because it displaces the other three but carries no structural role.
| Macronutrient | kcal per gram | Common target |
|---|---|---|
| Protein | 4 | 1.6–2.2 g/kg for muscle retention (0.8 g/kg RDA floor) |
| Carbohydrate | 4 | Fills remaining calories after protein and fat |
| Fat | 9 | ≥0.5 g/kg for hormone function |
| Alcohol | 7 | No target; counts against the daily total |
Percentage splits (share of total calories) sit inside the Acceptable Macronutrient Distribution Ranges of carbohydrate 45–65%, protein 10–35%, fat 20–35%:
| Split (C / P / F) | Style |
|---|---|
| 50 / 20 / 30 | Balanced, AMDR-centered |
| 40 / 30 / 30 | Higher-protein maintenance |
| 30 / 40 / 30 | Muscle-retention cut |
| 20 / 25 / 55 | Low-carbohydrate |
Unit conversions and a worked figure
The formulas run in kilograms and centimeters; convert before substituting.
| From | To | Multiply by |
|---|---|---|
| pounds | kilograms | 0.453592 |
| kilograms | pounds | 2.20462 |
| inches | centimeters | 2.54 |
| feet + inches | centimeters | (feet·12 + inches) · 2.54 |
Worked end to end for a 68 kg (150 lb), 165 cm (5′5″), 35-year-old woman, moderately active, aiming for slow loss:
| Step | Math | Result |
|---|---|---|
| BMR (Mifflin–St Jeor) | 10·68 + 6.25·165 − 5·35 − 161 | 1,375 kcal |
| TDEE | 1,375 × 1.55 | 2,131 kcal |
| Goal (−250) | 2,131 − 250 | 1,881 kcal |
| Protein (1.8 g/kg) | 68 × 1.8 | 122 g |