Best Free TDEE Calculator Online in 2026 — No Account Required
What to Look for in a TDEE Calculator
A good TDEE calculator should: use the Mifflin-St Jeor formula (the most accurate for general adults), support multiple activity levels, show both BMR and TDEE separately, work in both metric and imperial, and not require sign-up. TDEE Calculator meets all of these criteria.
Mifflin-St Jeor vs. Harris-Benedict: Which Is Better?
The Harris-Benedict equation (1919) was the original BMR formula. Mifflin-St Jeor (1990) was developed on a modern population and consistently outperforms it in accuracy. Studies show Mifflin-St Jeor is within 10% of measured RMR for 82% of people versus 69% for Harris-Benedict. FreeBMIKit uses Mifflin-St Jeor.
Activity Level Guide: Which to Choose
Sedentary: desk job, no exercise. Lightly active: 1–3 workouts/week. Moderately active: 3–5 workouts/week. Very active: 6–7 hard workouts/week. Extra active: physical job + daily training. Most office workers who go to the gym 3x/week should select ‘moderately active’ — people consistently overestimate their activity level by one tier.
What to Do With Your TDEE Number
Maintenance: eat your TDEE. Weight loss: eat 300–500 below. Muscle gain: eat 200–300 above. Track for 2–4 weeks and adjust if the scale doesn’t move. Real-world TDEE often differs from calculated TDEE by up to 15% — use the calculator as a starting point, then calibrate from your actual results.
Frequently Asked Questions
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Open TDEE Calculator — instant results, no sign-up, metric and imperial supported.
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