How Is TDEE Calculated? Formula and Worked Example

Calculating TDEE is one of the most useful pieces of math in fitness. Once you know the formula, you can estimate maintenance calories anywhere — no app required. The standard approach has two steps: estimate Basal Metabolic Rate with the Mifflin–St Jeor equation, then scale by an activity factor that reflects how much you move on a normal day.

This guide walks through both steps, the activity multipliers, and a complete worked example so you can verify any TDEE calculator's number — including ours.

Step 1 — calculate BMR with Mifflin–St Jeor

The Mifflin–St Jeor equation is the most accurate widely-used BMR formula for the general adult population. It was published in 1990 and remains the gold standard recommended by the Academy of Nutrition and Dietetics.

Men

BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5

Women

BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161

If you only have imperial units

Convert first: pounds to kilograms by dividing by 2.2046; inches to centimetres by multiplying by 2.54. Then apply the formula above.

Step 2 — multiply BMR by an activity multiplier

BMR is just the rest baseline. To get TDEE, multiply BMR by a number that approximates how much movement and exercise you add on top.

• 1.20 — Sedentary: desk job, almost no exercise.
• 1.375 — Lightly active: light exercise 1–3 days per week, or a job with some standing.
• 1.55 — Moderately active: moderate exercise 3–5 days per week.
• 1.725 — Very active: hard exercise 6–7 days per week.
• 1.90 — Extra active: intense daily training or a physical job on top of training.

Why Mifflin–St Jeor and not Harris–Benedict?

Both formulas exist, but the original Harris–Benedict equation (1919) was developed on a small, mostly Caucasian sample and overestimates BMR in modern populations by about 5%. The 1990 Mifflin–St Jeor equation was developed on a broader, more diverse sample and lands within ~10% of measured BMR for roughly 80% of healthy adults.

Some calculators also use the Katch–McArdle formula, which works from lean body mass instead of total weight. Katch–McArdle is more accurate if you have a reliable body fat measurement — otherwise Mifflin–St Jeor wins.

Worked example

A 28-year-old woman who is 165 cm and 62 kg, training in the gym four times per week, would compute her TDEE as follows:

BMR = 10 × 62 + 6.25 × 165 − 5 × 28 − 161 = 620 + 1,031.25 − 140 − 161 = 1,350 kcal.

TDEE = 1,350 × 1.55 (moderate) = 2,093 kcal/day. To cut fat at roughly 0.5 kg per week she would eat around 1,593 kcal.

Common mistakes and misconceptions

• Using the wrong gender constant. The +5 vs −161 swap is worth ~166 calories per day. Double-check before trusting the result.
• Picking too-high an activity multiplier. 1.725 is not three gym sessions per week. It means hard daily training. Most desk workers who lift 3–4 times per week sit at 1.45–1.55.
• Forgetting unit conversions. Plugging pounds and inches into the metric formula will produce nonsense — always convert first.
• Calculating once and never updating. Your BMR drops as you lose mass and rises as you gain. Recalculate every 5–10 kg change.

Tips for accurate TDEE calculations

• Measure weight first thing in the morning after using the bathroom, in the same clothing, for the most consistent baseline.
• Measure height once a year — adults can lose 1–2 cm over a decade through spinal compression.
• If you are between two activity levels, pick the lower one. You can always add a deliberate snack, but you cannot un-eat calories at night.
• After two weeks at your calculated TDEE, if weight is stable to within 0.3 kg, you have your real maintenance number. If it drifted, adjust by 100–200 kcal.

Related questions

Keep reading on this site

• Free TDEE & Body Fat Calculator — skip the math — get TDEE, macros, and goal calories
• TDEE calculator for men — male Mifflin–St Jeor preset
• TDEE calculator for women — female Mifflin–St Jeor preset
• Daily calorie burn breakdown — resting vs activity calories