TDEE Calculator

BMR is the energy your body uses at complete rest just to keep functioning — breathing, circulation, and organ activity. TDEE is that figure scaled up to include everything else you do: walking, working, exercising, and digesting food. TDEE is always the larger number, and it is the one to use when planning intake, since nobody spends the whole day at rest.

It is an estimate, typically within about ten percent for most healthy adults. Mifflin-St Jeor is among the more reliable resting-metabolism formulas available, but individual metabolism still varies with body composition, genetics, and medical conditions, and activity multipliers are the roughest part of the calculation, since most people misjudge their own activity level. Treat the result as a starting point and adjust based on real weight trends over two to three weeks.

For most healthy adults, yes. Harris-Benedict dates to 1919 and was built from a small, mostly lean study population; Mifflin-St Jeor, published in 1990, was developed on a larger and more representative sample. A 2005 systematic review in the Journal of the American Dietetic Association found Mifflin-St Jeor predicted resting metabolic rate within 10% of measured values more consistently than Harris-Benedict, which is why it's the more commonly recommended default today.

The Mifflin-St Jeor equation includes a fixed constant that differs by sex — plus 5 for men, minus 161 for women — because men and women of the same height, weight, and age tend to carry different amounts of lean muscle versus fat on average, and muscle burns more calories at rest than fat does. It's a term in the published formula, not a judgment about any individual's body composition.

A common, sustainable starting point is eating 300-500 calories below your TDEE per day, which tends to produce a gradual, muscle-sparing rate of loss for most people. Cutting much further increases the risk of losing lean muscle along with fat and makes the deficit harder to sustain. Recalculate every 10-15 pounds lost, since a lower body weight also lowers both BMR and TDEE.

A modest surplus of roughly 200-300 calories above TDEE, combined with resistance training, is generally enough to support muscle gain without adding excess fat too quickly. Larger surpluses don't build muscle meaningfully faster past a certain point — they mostly add more fat gain alongside it, since the body can only build new muscle tissue at a limited rate.

Not for predicting real-world results over time. The old rule of thumb — a 3,500-calorie deficit equals one pound of fat lost — treats weight loss as a fixed, static conversion. Research led by NIH researcher Kevin Hall, published in The Lancet in 2011, showed the body's energy expenditure adapts as weight changes, so early loss is faster than the 3,500 rule predicts and later loss slows down, which is the basis for the NIH's dynamic Body Weight Planner tool.

Pick based on your typical week, not your best week. Sedentary means a desk job with little deliberate exercise; lightly active is exercise 1-3 days a week; moderately active is 3-5 days; very active is 6-7 days or a physically demanding job; extra active covers a physical job combined with hard training. Self-reported activity is one of the least precise inputs in this calculator, since a single category has to stand in for a whole week that varies day to day, so if you're between two levels, the lower one is the safer starting guess.

TDEE from any formula is an estimate, not a measured number — actual metabolic rate can vary by roughly 10% between two people with identical stats, and activity multipliers are broad categories that don't capture your specific week. Water retention, sodium intake, and hormonal cycles also shift the scale independently of fat loss or gain. If your real-world trend over 2-3 weeks consistently differs from the prediction, adjust your calorie target to match reality rather than the formula.

Yes. Both BMR and TDEE fall as body weight drops, because a lighter body requires less energy to maintain and moves less mass during daily activity — part of why weight loss tends to slow over time even on an unchanged calorie target. Recalculating TDEE periodically as your weight changes keeps the estimate aligned with your current body rather than the one you started with.

There isn't one universally most accurate formula — it depends on what you can measure. Mifflin-St Jeor, which this calculator uses, needs only weight, height, age, and sex, and predicts resting metabolic rate within about 10% of measured values for most healthy adults, per a 2005 systematic review. Katch-McArdle, used by some other calculators, can edge it out for very lean or muscular people, but only if you already know your body fat percentage accurately — a harder, more error-prone number to nail down than the accuracy improvement it buys you.

NEAT stands for non-exercise activity thermogenesis: the calories burned by everything in a day that isn't sleeping, eating, or formal exercise, including fidgeting, standing, walking around the house, and carrying groceries. Research by endocrinologist James Levine found NEAT can vary by more than 2,000 calories a day between similarly sized people with identical workout routines, based purely on how much they move outside the gym. That's a big reason two people with the same calculated TDEE can see different real-world results — the activity multiplier only assigns one of five broad categories and can't capture how fidgety or sedentary someone actually is between workouts.