BMR and TDEE
Mifflin–St Jeor BMR, then activity-based total daily burn
BMR and TDEE
BMR is an estimate of calories burned at complete rest. TDEE multiplies BMR by an activity factor so you get a rough maintenance budget. Both numbers are models, not lab measurements.
Equations on this page
Mifflin–St Jeor estimates resting metabolism—the calories you would burn lying quietly in a warm room after an overnight fast. It does not include digestion, fidgeting, or exercise.
Men: BMR = 10w + 6.25h − 5a + 5
Women: BMR = 10w + 6.25h − 5a − 161
Symbols: w weight in kilograms, h height in centimetres, a age in years (this calculator floors decimals to a whole year before plugging in).
TDEE is BMR × activity factor. Factors match the five-row list in the tool (1.2, 1.375, 1.55, 1.725, 1.9)—the same ladder many macro spreadsheets use, though labels vary slightly between authors.
Activity factors (reference)
| Label in the tool | Multiplier | Typical pattern |
|---|---|---|
| Sedentary | 1.2 | Mostly sitting; little structured exercise. |
| Light | 1.375 | Light sessions or walking a few days each week. |
| Moderate | 1.55 | Planned training mid-week several times. |
| Active | 1.725 | Hard training or a physical job most days. |
| Very active | 1.9 | Near-daily intense work plus sport, or similar load. |
Worth keeping in mind
- Older adults and people with major lean-mass loss sometimes need clinician-guided adjustments; predictive equations miss muscle mass unless you add body-composition data elsewhere.
- Medications, caffeine, stress, and room temperature can swing a measured resting metabolic rate by a few percent day to day.
- For weight-to-height screening without calories, the BMI calculator stays the lighter-weight option.
Quick guide
1. What do I fill in first?
- Choose male or female, enter age, height, and weight in either metric or US units.
- Select the activity row that matches an ordinary week—not a vacation or a competition taper.
- Hit Calculate or pause typing; the page recalculates after a short delay whenever inputs change.
2. What math runs here?
BMR uses the Mifflin–St Jeor formula with weight in kilograms, height in centimetres, and age in years.
TDEE multiplies that BMR by one of five activity factors (1.2 through 1.9) borrowed from common sports-nutrition tables.
3. Why might my wearable disagree?
Every predictive equation spreads error. Two people with identical stats can differ in thyroid meds, genetics, sleep debt, and non-exercise movement.
Calorimetry in a lab beats any website; treat the output as a starting number you adjust with two to four weeks of real-world weight trend.
4. Why use an in-browser calculator?
- Mifflin–St Jeor tends to track indirect calorimetry a bit better than the older Harris–Benedict rewrite for many modern adults.
- Activity multipliers are spelled out next to each radio option so you are not guessing what “moderate” means in isolation.
- Nothing leaves the tab: no account wall, no PDF export chain.
5. Typical uses
- Setting a rough calorie target before you talk it through with a dietitian or coach.
- Teaching students where the 10 × weight + 6.25 × height − 5 × age pattern comes from.
- Sanity-checking numbers from a spreadsheet or app that does not show its work.