How TDEE is calculated
TDEE starts with your BMR (basal metabolic rate), the energy your body uses at rest. We estimate it with Mifflin-St Jeor, or with Katch-McArdle if you enter a body-fat percentage. BMR is then multiplied by an activity factor:
| Activity level | Factor | Typical week |
|---|---|---|
| Sedentary | 1.2 | Desk job, little planned exercise |
| Lightly active | 1.375 | Light exercise 1–3 days |
| Moderately active | 1.55 | Moderate exercise 3–5 days |
| Very active | 1.725 | Hard exercise 6–7 days |
| Extra active | 1.9 | Hard daily training plus a physical job |
Worked example: a 30-year-old woman, 5 ft 5 in (165 cm) and 150 lb (68 kg), has a BMR of about 1,400 kcal. At a moderately active level, 1,400 × 1.55 gives a TDEE of about 2,170 kcal.
How accurate is a TDEE calculator?
Mifflin-St Jeor is one of the better-tested equations; in a systematic review it predicted resting metabolic rate within 10% of measured values for most healthy adults who were not obese. That still means some people are further off, and the activity factor adds more uncertainty. Most people overestimate their activity level, so if you are unsure between two levels, pick the lower one.
Find your real TDEE in three weeks
- Eat close to the calculated TDEE every day and log it honestly.
- Weigh yourself most mornings and take a weekly average.
- After two to three weeks, compare averages. If weight is stable, that is your TDEE. If it rose or fell, adjust: roughly 7,700 kcal per kg (3,500 per lb) of change spread over the period is a useful rough guide.
From TDEE to a goal
To lose weight, eat below TDEE; to gain, eat above it. The calculator shows a 20% deficit and a 10% surplus, the same settings our weight loss and muscle gain calculators use. To split those calories into protein, carbs and fat, use the macro calculator.
TDEE Calculator FAQ
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest. TDEE adds everything else: daily movement, exercise and digesting food.
Should I eat my TDEE or my BMR to lose weight?
Eat below your TDEE, not at your BMR. A deficit of 10–20% below TDEE is a common starting point and is usually above BMR.
Does TDEE change as I lose weight?
Yes. A lighter body burns less, so recalculate after every 3–4 kg (7–9 lb) of change.
Do fitness trackers measure TDEE?
They estimate it. Wrist-worn devices can be noticeably off for calories burned, so treat their numbers as another estimate and rely on your weight trend.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990.
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association, 2005.
General information only, not medical advice. Talk to a qualified healthcare professional before changing your diet, especially if you are pregnant, breastfeeding, under 18 or managing a medical condition.