Free tool
TDEE calculator that knows the number moves
Work out your BMR, maintenance calories, and cut / maintain / bulk targets in seconds - metric or imperial, no signup. Then see why a one-off formula goes stale, and how FORM keeps it honest week to week.
Daily calories by goal
Estimates from Mifflin-St Jeor. A formula guesses once from averages, and your real TDEE drifts with adaptation and daily movement, which is why FORM re-checks it from your weight trend every week.
How it works
BMR, then TDEE
Your BMR is what your body burns just to keep you alive at rest - breathing, circulation, keeping warm. This tool estimates it with the Mifflin-St Jeor equation, then multiplies by an activity factor to get your TDEE: the calories you actually burn across a normal day. Eat at TDEE to hold, under it to lose, over it to gain.
The catch
Why the number won't stay put
A calculator guesses once from population averages. But your real maintenance drifts: lose weight and you need fewer calories, diet hard and your non-exercise movement quietly drops, and metabolic adaptation shaves a bit more off. That's why people stall on a number that used to work. FORM re-estimates your maintenance from your smoothed weight trend every week and nudges your target - so a calculator is your day-one starting point, and FORM is what keeps it accurate from there.
Want the full macro split?
The macro calculator turns these calories into protein-first grams for your goal. Or skip the maths entirely - FORM sets and adapts your targets for you.
FAQ
TDEE calculator: FAQ
What is TDEE?
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a day: your BMR (what you burn at rest) multiplied by an activity factor for movement and exercise. Eat at your TDEE to maintain, below it to lose fat, above it to gain.
How is TDEE calculated?
This calculator uses the Mifflin-St Jeor equation for BMR - the most widely used and reasonably accurate formula - then multiplies by an activity factor (1.2 for a desk job up to 1.9 for very active). It is an estimate from population averages, so treat the number as a well-informed starting point, not a fixed truth.
Why does my TDEE change over time?
Your TDEE is not static. As you lose weight your body needs fewer calories, your non-exercise movement (NEAT) can drop on a diet, and metabolic adaptation kicks in. That is why a number from a calculator goes stale - and why FORM re-estimates your real maintenance from your smoothed weight trend and intake each week, instead of leaving you on one formula forever.
How many calories should I eat to lose weight?
A moderate fat-loss target is roughly a 10-20% deficit below your TDEE - the calculator shows both. Bigger deficits lose faster but are harder to sustain and risk muscle loss, so protein-first eating and a sensible deficit win over time. FORM adjusts the deficit as your trend moves so progress stays on pace without crashing.
Is this TDEE calculator accurate?
It is as accurate as any formula-based estimate - within a few hundred calories for most people. The honest way to use it: start here, eat consistently for 2-3 weeks, and adjust based on what your weight trend actually does. That real-world feedback loop is exactly what FORM automates.