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TDEE, BMR and Calories: What the Numbers Mean
BMR, TDEE and your calorie target sound technical but the idea is simple. Learn what each number means, how they're estimated, and how to use them to lose, gain or maintain weight.
Updated 20 August 2026 · 2 min read
If you've ever tried to plan your eating around a number, you've met the alphabet soup: BMR, TDEE, maintenance calories. They sound technical, but the underlying idea is simple — how much energy your body uses in a day, and how to eat around it.
BMR: your body at rest
Basal Metabolic Rate is the energy your body burns just to stay alive — breathing, circulation, keeping your organs running — if you did nothing but rest all day. It's the biggest single chunk of your daily energy use, typically 60–70% of the total.
It's estimated from your sex, age, height and weight using an equation like Mifflin-St Jeor. You can't measure it exactly at home, but the estimate is a solid starting point.
TDEE: your body in real life
Total Daily Energy Expenditure is your BMR plus everything else you do — walking, working, exercising, even fidgeting. It's calculated by multiplying BMR by an activity factor:
Your TDEE is your maintenance calories — eat that amount and your weight holds roughly steady. The calorie calculator estimates both BMR and TDEE from your details and activity level.
Turning TDEE into a goal
Once you know your maintenance number, the strategy is straightforward:
- To lose weight, eat below your TDEE. A deficit of around 500 kcal a day is a common target for roughly 0.5 kg (about 1 lb) of loss per week.
- To maintain, eat around your TDEE.
- To gain, eat above it — a modest surplus supports muscle gain without excessive fat.
Within that total, how you split protein, carbohydrate and fat is up to your goals and preferences. A macronutrient calculator turns a calorie target into grams of each.
Treat the number as a starting point
These are estimates, not laws of physics for your exact body. Two people with identical stats can have real TDEEs that differ by a few hundred calories. Use the calculated figure to begin, track your actual weight over two to three weeks, and adjust based on what really happens — the scale is the feedback loop, not the formula.
Frequently asked questions
- What's the difference between BMR and TDEE?
- BMR is the energy your body uses at complete rest. TDEE is BMR multiplied by an activity factor, so it reflects the calories you actually burn across a normal day including movement and exercise. TDEE is your maintenance level.
- How big a calorie deficit should I aim for?
- A moderate deficit of around 500 kcal below your TDEE typically leads to about 0.5 kg (1 lb) of loss per week. Very aggressive deficits are hard to sustain and can cost you muscle, so moderate and consistent usually wins.