How to turn your TDEE into a daily calorie target

Your TDEE is a number that describes what you burn. It is not a number that describes what you should eat, and treating it as one is the most common mistake people make with it. Here is the conversion, step by step, with the reasoning at each point.

Step 1: get the number, and treat it as a starting point

Start with the TDEE calculator. It estimates your basal metabolic rate using the Mifflin-St Jeor equation, then multiplies that by an activity multiplier between 1.2 and 1.9.

The BMR half is arithmetic from your age, sex, height and weight, and it is fairly reliable. The activity multiplier is a five-step self-assessment, and it is the weakest link in the whole chain. It cannot tell the difference between a desk job that involves a lot of walking around and one that does not. Expect the result to be within roughly 10% of your real burn, and treat it as a place to start rather than a fact.

Step 2: decide which direction you are going

Now the conversion itself, which is arithmetic rather than judgement:

If you are not sure which you want, maintenance is the useful one to measure first, for a reason that is not obvious until you have done it: it gives you a real, personal reference point. Once you know what your body actually weighs in calories, every later adjustment is a small change from a known number rather than a guess from scratch.

Step 3: size the change, not the whole gap

This is where most people overcorrect. The calorie deficit calculator works from the constant that 1 kg of body fat is worth about 7,700 kcal, so a 0.5 kg per week loss works out to roughly 550 kcal a day. That is not the same as eating 2,000 calories a day.

Two reasons to keep the deficit modest. A large one is hard to sustain, and adherence is the limiting factor on how much fat people actually lose — not the size of the number on the paper. And if you cut hard, some of what comes off is lean mass rather than fat, which is why the protein target matters more in a deficit than at maintenance.

For the same reason, the surplus side has a ceiling. The calorie surplus calculator will not return a target above 5,000 calories, because past that point you are mostly adding fat rather than muscle. Gaining well is a small surplus held consistently, not a large one held briefly.

Step 4: close the loop, because the number will drift

Your TDEE is not a constant. It falls as you get lighter, because you have less body to carry around. It moves as your activity changes, and as your body adapts to a deficit. Which is why a maintenance number is best found by watching your weight trend over several weeks rather than read off a calculator.

So: pick a target, give it two to three weeks, then look at the trend in your weight rather than at any single morning. If it is not moving in the direction you wanted, adjust the target by 100–200 calories rather than doubling the change. That loop is the part that actually works, and no calculator replaces it.

What this guide does not cover

Where these targets are not appropriate, and what to do instead. If you have a medical condition, are pregnant, or are under 18, a published equation derived from average adult data is the wrong tool and a clinician is the right one. The safety limits on the deficit and surplus calculators exist to stop this site returning an unreasonable number, not to make the number correct for you.

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