Adaptive TDEE Calculator
Forget formula-based estimates. Enter 14+ days of weight and calorie data and our adaptive engine derives your real maintenance number — accurate to the calories your body actually burns.
Why "adaptive" TDEE works
Every traditional TDEE calculator gives you the average energy expenditure for someone of your height, weight, sex, and stated activity level. Useful as a starting point — but your real number can drift 10–25% from that average due to:
- Differences in NEAT (the calories you burn fidgeting and moving outside the gym).
- Adaptive thermogenesis after weeks of dieting.
- Errors in food labelling (US/EU labels can legally be off by ±20%).
- How honestly you self-report activity level.
The math, simplified
The first law of thermodynamics applied to your body says: calories in − calories out = energy stored or released. Each kilogram of body fat stores roughly 7,700 kcal. So if you tracked your intake and weight for D days, your real maintenance is:
If you ate slightly under maintenance and lost 1 kg in 14 days, your true TDEE is your average intake + (7,700 / 14) ≈ +550 kcal/day above what you actually ate. No formula required.
Common questions
Why is this more accurate than a regular TDEE calculator?
Standard TDEE formulas estimate maintenance from height, weight, age, and activity — they cannot account for your individual metabolism, NEAT, food labelling errors, or training history. Adaptive TDEE measures the result of your actual eating: by tying calorie intake to weight change, it produces a number specific to your body.
How much data do I need?
Minimum 7 days, ideally 14–28. The more data, the smaller the noise from water-weight fluctuation, glycogen, and food-intake estimation errors.
Won't water weight throw off the calculation?
Some, yes — that's why short windows are unreliable. Over 14+ days the day-to-day water and gut-content noise averages out, leaving a clean read on actual energy balance.
Does my data leave my device?
No. Calculations run in JavaScript in your browser. "Save data" stores it in your local browser storage; we never see it.