How to Calculate Your TDEE (3 Methods)
To calculate TDEE, estimate BMR first, multiply it by an activity factor, then sanity-check the result against body-weight trends. The formula is useful, but the follow-up check is where the number becomes personal.
Step 1: estimate BMR
BMR is the resting part of the calculation. TDEETools uses the Mifflin-St Jeor equation when body fat percentage is not supplied because it is a widely used adult resting energy equation.
For metric inputs, the common form is: men: 10 x weight kg + 6.25 x height cm - 5 x age + 5. Women: 10 x weight kg + 6.25 x height cm - 5 x age - 161.
Step 2: multiply by activity
After BMR, the calculator applies an activity multiplier. A sedentary day is not the same as a day with a physical job, long commute on foot, and hard training. The multiplier is a rough way to include that difference.
The safest choice is usually the activity level you can defend with your average week, not your best week. If you lift three times but sit most of the day and average 4,000 steps, you may still be closer to lightly active than moderately active.
- Sedentary: desk work and little deliberate exercise.
- Light: some exercise or regular walking.
- Moderate: structured training and a fairly active weekly routine.
- Very active: hard training, physical work, or high daily movement.
Step 3: use body fat only when the estimate is credible
If you enter body fat percentage, TDEETools uses lean body mass to estimate resting needs. This can help for people whose body composition is far from average, but only if the body-fat estimate is decent.
A casual visual guess can be worse than leaving the field blank. A DEXA scan, consistent caliper measurement, or a well-tracked smart scale trend is more useful than a one-off number.
Step 4: validate the number
No calculator can see your actual food intake, water shifts, non-exercise movement, or training fatigue. Use the calculated TDEE as the first target, then compare it with two to four weeks of calorie and weight data.
If you eat 2,200 calories for three weeks and your weekly average weight is flat, your maintenance is probably close to 2,200, even if the original calculator estimate was a little higher or lower.
Sources and method notes
TDEETools articles explain calculator outputs in plain English. They are educational and are not medical advice.