TDEE Calculator: Maintenance Calories & Deficit Targets

Almost every weight-loss plan, however it is dressed up, reduces to one number: the calories your body spends in a day. Get that number roughly right and the rest becomes arithmetic. Get it wrong, and you are either cutting too hard and burning out, or barely cutting at all and wondering why the scale will not move. Total Daily Energy Expenditure is that number. It is not a fixed property of your body so much as a moving estimate, but a good estimate is enough to plan around, and that is what this page is for.

How to use this calculator

In the tool above, enter your sex, age, height, weight, and an honest reading of your activity level. It returns three figures that matter: your resting metabolic rate, your maintenance calories, and a set of deficit targets for losing weight at different speeds. It also shows a daily protein goal, because how you lose weight matters as much as how fast. Switch between metric and imperial units with the toggle. Nothing is stored or sent anywhere; the calculation runs entirely in your browser.

What TDEE actually measures

Your TDEE is built from several parts. The largest, usually sixty to seventy percent of the total, is your basal metabolic rate: the energy your body spends keeping you alive at rest, running your heart, brain, kidneys, and the constant turnover of tissue. On top of that sits the energy of movement, both deliberate exercise and the fidgeting, walking, and standing that fill a day. A smaller slice, around ten percent, is the thermic effect of food, the calories spent digesting what you eat. This calculator estimates your resting rate with the Mifflin-St Jeor equation, the predictive formula that performs most reliably across healthy adults, then applies an activity multiplier to reach TDEE.

Because the resting rate depends on how much metabolically active tissue you carry, two people of the same weight can have different numbers. It also explains why the figure drifts down as you lose weight: a smaller body burns less. If you have ever wondered whether your own rate is unusually low, the honest answer is examined in our piece on whether a slow metabolism is real, and the vocabulary around it is untangled in the metabolism glossary.

Choosing your activity level honestly

The single most common way people misjudge their TDEE is by overstating activity. A structured gym session three times a week does not make someone "very active" if the other twenty-three hours of each day are spent sitting. For most people with desk jobs who exercise a few times a week, "lightly active" or "moderately active" is the truthful choice. When in doubt, pick the lower option: it is far easier to add food back if you are losing too fast than to discover months later that your maintenance estimate was inflated the whole time.

How big a calorie deficit should you aim for?

A deficit is simply eating below your TDEE, and its size sets your rate of loss. Roughly seven thousand seven hundred calories is stored in a kilogram of body fat, so a deficit of five hundred calories a day works out to about half a kilogram, or a little over a pound, a week. That standard deficit is the one most people should default to. It is aggressive enough to show clear progress within a month, gentle enough to be sustainable, and modest enough that most of the loss comes from fat rather than muscle.

The calculator shows a milder option and a faster one on either side of that standard. Faster is tempting, but a very large deficit brings real costs: hunger that becomes hard to override, fatigue, a sharper metabolic slowdown, and a greater share of weight lost as lean tissue. This is part of why so many aggressive diets unravel, a pattern explored in depth in our article on why diets fail long term. The tool flags any target that falls below a safe calorie floor, which you should not go under without medical supervision.

Why the calorie math shifts on a GLP-1 medication

A GLP-1 medication does not change the numbers this calculator produces. Your TDEE is set by your body size, composition, and movement, and no medication meaningfully raises it. What the medication changes is the other side of the equation, the side that is usually the hard part: intake. By dampening appetite and quieting the constant background pull toward food, it makes eating below your TDEE far easier to sustain than willpower alone allows. In effect, the deficit this tool describes becomes reachable without the daily struggle, which is the real mechanism behind the results, laid out in our comparison of GLP-1 versus traditional weight loss.

That ease introduces its own risk. When appetite drops sharply, it is easy to eat far too little, or to skimp on protein, and lose muscle alongside fat. So the target on a GLP-1 is not to eat as little as the medication allows, but to hit a genuine, measured deficit while still eating enough total food and enough protein. The maintenance figure above remains the number to stay under; the protein goal beside it becomes more important, not less.

Protecting muscle: protein and the deficit

In any deficit, the body draws on both fat and lean tissue for energy. Two things bias that split toward fat: resistance training and adequate protein. The calculator sets a protein goal of about 1.6 grams per kilogram of body weight, near the top of the range shown to preserve lean mass during weight loss. Hitting it reliably is harder when appetite is suppressed, which is exactly why it deserves attention on a GLP-1; the practical strategies for doing so are covered in our guide to protein targets on GLP-1.

The limits of any TDEE estimate

No equation can measure your metabolism directly; it can only predict it from population averages. Real people scatter around those averages, and factors the formula cannot see, such as your exact body composition, hormonal state, medications, and daily movement, all move the true figure. Treat the output here as a well-reasoned first draft. Eat at the maintenance number for two to three weeks, watch the trend on the scale rather than any single day, and adjust by small increments. The calculator gives you the starting point; your own data corrects it from there.