How to Calculate Your TDEE for Weight Loss (No Math Degree Required)

The calculation combines two estimates, so understanding where uncertainty enters is as important as doing the arithmetic.

How do you estimate TDEE?

TDEE = BMR × Activity Multiplier

Step 1: Your BMR (Basal Metabolic Rate)

Resting metabolic rate is energy used at rest. Mifflin–St Jeor is a commonly used prediction equation, but it is not a direct measurement and is not exact for every person. (Mifflin et al., 1990)

• Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
• Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Example: 35-year-old man, 180 lbs (82 kg), 5'10" (178 cm):
BMR = (10 × 82) + (6.25 × 178) − (5 × 35) + 5 = 1,762 calories

Step 2: Your activity multiplier

Activity multipliers are rough conventions used by some calculators, not validated measurements of an individual's daily expenditure:

• 1.2 — Sedentary: desk job, no exercise
• 1.375 — Lightly active: light walks, 1–2 workouts/week
• 1.55 — Moderately active: 3–5 workouts/week
• 1.725 — Very active: 6–7 hard workouts/week or physical job
• 1.9 — Extremely active: elite athlete, manual labor + training

Activity labels differ among calculators, and a few workouts per week do not map neatly to one universal multiplier. Treat the estimate as a starting point and compare it with observed trends over time.

Putting it together

Same 35-year-old man, moderately active:
TDEE = 1,762 × 1.55 = 2,732 calories to maintain weight.

How should you use a TDEE estimate for a weight goal?

Calorie targets are estimates and should be appropriate for a person's age, health, and circumstances. A healthcare professional can help set a safe, realistic plan.

• A calculator does not predict a precise weekly rate of weight change.
• Very restrictive targets may be unsafe, particularly for people with medical needs.
• Targets may need to change as circumstances and health change.

For illustration, eating 2,300 calories against a hypothetical 2,732-calorie estimate would create a nominal 432-calorie gap. Actual weight change cannot be predicted exactly from this calculation.

Why can a TDEE estimate be inaccurate?

1. They treat a calculator's estimate as an exact measurement.
2. They may misjudge activity or food amounts.
3. They expect weight change to follow a fixed mathematical schedule.
4. They overlook health, medication, and other factors that can affect weight.

The smarter formula (if you know your body fat %)

If you have a DEXA scan, smart scale, or accurate body fat estimate, use Katch-McArdle:

BMR = 370 + (21.6 × lean body mass in kg)

This uses estimated lean mass, but no calculator is consistently accurate for every individual. Consumer smart scales may not provide a precise body-fat measurement.

The bottom line

A TDEE calculator is only a starting estimate. If weight change is a goal, use a modest, sustainable approach and review trends over time; consider a healthcare professional for individualized advice.

MyDietingApp estimates your TDEE from the profile details you provide using a prediction equation, and can suggest a target based on your goal. These are estimates, not measurements; compare them with your experience and seek individualized guidance when needed.