How accurate is a TDEE calculator?
TDEE estimates are typically within about 10% when your activity level is honest. Here is the honest breakdown of what that means for your weight loss.
The short answer
Studies of energy expenditure suggest estimates of daily calorie burn can be off by roughly ±10%. For someone who should eat ~2,300 kcal/day, the calculator could be off by ~230 kcal/day. Over one month, that is ~7,000 calories — about 2 lbs of weight.
The biggest source of error
Most people overestimate how much they work out. If you should be in the “Light” category but pick “Moderate”, the gap is about 250 kcal/day. Pick the tier honestly; your results will be far closer to real.
What to do with an inaccurate estimate
- Use the TDEE as a reasonable starting estimate.
- Eat at your target for 2–3 weeks, track weight.
- Adjust by ±100 kcal/day if weight does not match.
Frequently asked questions
How accurate is the TDEE estimation?
Within ~10% if activity is honest. Most overestimate by one tier; the gap is ~250 kcal/day.
Which formula does this calculator use?
The Mifflin-St Jeor equation is primary; Katch-McArdle when body fat is known; Harris-Benedict supported.
Why does my TDEE change over time?
TDEE drops as you lose weight, during dieting, and with age. Recalculate every 6–8 weeks.