TDEE in one sentence
TDEE, or total daily energy expenditure, is all the energy your body uses in a day: keeping you alive at rest, digesting food and moving around. If you eat about that much on average, your weight tends to hold steady.
That's why fitness sites call it maintenance calories. It's the number everything else gets built on, from a weight-loss target to a muscle-gain plan.
The three parts of TDEE
The National Academies break TDEE into three parts. Resting energy keeps your heart beating, your lungs working and your body warm. For most people it's the biggest share.
The thermic effect of food is the energy you spend digesting and storing what you eat. Physical activity covers everything else. That means planned exercise plus all the movement you don't think of as exercise, like walking to the bus, standing at work, cooking and fidgeting.
- Resting energy: the largest and most stable part
- Thermic effect of food: the energy cost of digestion
- Physical activity: exercise plus everyday movement, the part that varies most
How calculators estimate it
Most calculators, ours included, take two steps. First they predict resting energy from your weight, height, age and sex, usually with the Mifflin-St Jeor equation. Then they multiply by an activity factor between 1.2 and 1.9.
Take a 40-year-old woman who weighs 65 kg and is 165 cm tall. Mifflin-St Jeor puts her resting energy at about 1,320 kcal a day. If her week is light, at 1.375, her TDEE comes out around 1,815. If she's moderately active, at 1.55, it's about 2,046.
Why your estimate can be off
The resting equation predicts an average person with your measurements. It was built from 498 healthy adults, and real people sit above and below that average.
The bigger source of error is the activity factor. People tend to judge their week by their hardest workout, and a jump from 1.375 to 1.55 adds a few hundred calories. Two people with the same gym schedule can burn very different amounts if one has a desk job and the other is on their feet all day.
How to find your real number
The lab gold standard, doubly labeled water, measures energy use over days or weeks, but it's expensive and mostly used in research. For everyone else, your own trend works.
Start with a calculator estimate from our TDEE calculator. Eat close to it, log your intake honestly and weigh yourself under the same conditions for a few weeks. If your average weight holds, you've found your maintenance. If it drifts, nudge your estimate and keep going. Look at weekly averages rather than single weigh-ins, because water and digestion move the scale day to day.
TDEE changes as you change
Your TDEE isn't fixed. Lose weight and your resting energy drops, because a smaller body costs less to run. Change jobs, start walking to work or take a few weeks off training and your activity share shifts too.
NIDDK's Body Weight Planner models this on purpose, because a fixed rule overstates how much weight you'll lose over time. Recalculate after a real change in your weight or routine. If you have a health condition, are pregnant, or are recovering from an eating disorder, work out your needs with a clinician or registered dietitian.
Frequently asked questions
What does TDEE stand for?
Total daily energy expenditure: the total calories your body uses in a day, including rest, digestion and all physical activity.
Is BMR part of TDEE?
Yes. Resting or basal energy is the base of TDEE. Calculators multiply it by an activity factor to add digestion and movement on top.
Does TDEE go down when you lose weight?
Usually, yes. A lighter body needs less energy at rest and to move, so recalculate after meaningful weight change.
Can I measure my TDEE exactly?
Only in a lab, with methods like doubly labeled water. At home, tracking your intake against your weight trend for a few weeks gets you a practical answer.
References
These sources support the method or guidance used for TDEE Calculator. Verify time-sensitive rules at the source.
Try the calculator
Open TDEE Calculator, enter your scenario, and compare its supporting rows with this guide's method and checks.