Calorie Calculator — TDEE, Maintenance & Macros

From five inputs to a full daily calorie plan

This calorie calculator turns five everyday inputs — sex, age, height, weight, and activity level — into a complete daily plan: your BMR, your TDEE (maintenance calories), a goal-adjusted target for losing or gaining, and a protein, carb, and fat macro split in grams. It works in both imperial and metric, and every number updates the moment you change an input, so you can see how eating below or above maintenance moves your target.

It's a free online tool that runs entirely in your browser — no sign-up, nothing uploaded, no data stored. Already know your body mass index? Pair it with your calorie target for a fuller picture. One caveat up front: these are estimates for general information, not medical or nutrition advice.

How your BMR becomes a daily calorie target

The engine is two multiplications and one adjustment. First it estimates your Basal Metabolic Rate (BMR) — the energy you'd burn lying still all day — with the Mifflin-St Jeor equation, the BMR formula most validated for general use. For men it computes 10 × kg + 6.25 × cm − 5 × age + 5; for women the only change is the final constant: 10 × kg + 6.25 × cm − 5 × age − 161. If you enter feet, inches, and pounds, it converts them to centimetres and kilograms first, so the result is identical either way.

Next it multiplies your BMR by an activity multiplier between 1.2 and 1.9 to get your Total Daily Energy Expenditure (TDEE) — the calories you actually burn in a day. That TDEE is your maintenance level. Finally it applies your goal: subtract 500 for about a pound of loss a week, add 500 for a lean-bulk surplus, or leave it at TDEE to maintain. As a safety floor, the target never drops below 1,500 kcal for men or 1,200 for women.

Honest limit: because the formula assumes an average body composition, treat the output as a starting estimate, not a lab measurement — two people with the same stats can differ by 10–15%. Weigh yourself over 2–4 weeks and nudge the number up or down based on what the scale actually does. Anyone with a medical condition should check with a professional before making big changes.

The activity multiplier, with real-life examples

Picking the right activity level matters more than any other input, because it can swing your TDEE by hundreds of calories. The multiplier already bakes in your exercise for the week — you do not add workouts separately. Most people overestimate here, so when you're between two levels, choose the lower one:

A worked example, start to finish

Say a 30-year-old man is 180 cm and 80 kg and trains at the gym four times a week (moderately active, factor 1.55), with a goal to lose 1 lb / 0.5 kg per week. Here is exactly what the calculator does — the same arithmetic it runs on every keystroke:

Man, age 30, 180 cm, 80 kg, moderately active (factor 1.55)

Step 1 — BMR (Mifflin-St Jeor, men)
  BMR = 10 x 80 + 6.25 x 180 - 5 x 30 + 5
      = 1,780 kcal        (energy burned at complete rest)

Step 2 — TDEE = BMR x activity factor
  TDEE = 1,780 x 1.55
       = 2,759 kcal       (maintenance: eat this to hold weight)

Step 3 — Goal target (lose 1 lb / 0.5 kg per week = -500)
  Target = 2,759 - 500
         = 2,259 kcal/day  (above the 1,500 kcal men's floor)

Macros on 2,259 kcal, Balanced preset (30% / 40% / 30%)
  Protein = 2,259 x 0.30 / 4 = 169 g
  Carbs   = 2,259 x 0.40 / 4 = 226 g
  Fat     = 2,259 x 0.30 / 9 =  75 g

Protein and carbs divide by 4 (calories per gram) and fat by 9, which is why the fat grams look small even at 30% of calories. Switch the preset to High Protein or Low Carb and only the split changes — the calorie target stays the same. The tool also prints a “Calories for Every Goal” table so you can see maintenance, both deficits, and both surplus targets side by side.

How it compares to other formulas and trackers

Mifflin-St Jeor is the default in most modern calculators for a reason, but it is not the only way to estimate calories. Here is roughly how the common approaches line up — treat every cell as a general guide, since real accuracy always depends on your inputs:

Apps like MyFitnessPal or Cronometer are great for logging meals day to day, but the calorie goal they hand you is generated by a formula much like this one — so it's worth understanding the maths behind the number rather than trusting it blindly.

Common calorie-calculator mistakes to avoid

Overestimating your activity level

A few workouts a week is “lightly active,” not “very active.” Picking a level too high inflates your TDEE, so your deficit disappears and the weight-loss stalls. When in doubt, drop a level.

Eating your exercise calories back twice

The activity multiplier already includes your training. Adding “calories burned” from a watch on top of that double-counts the workout and quietly cancels your deficit.

Treating the number as exact

It's a research-based estimate, not a measurement. Real needs vary by 10–15%. Use it as a starting point, track your weight for 2–4 weeks, then adjust up or down from what really happens.

Cutting far too hard

A deficit much bigger than 500–750 kcal risks muscle loss and rebound. That's why the target floors at 1,500 kcal for men and 1,200 for women — going lower without supervision usually backfires.

Forgetting to recalculate

As your weight changes, so do your BMR and TDEE. Re-run the calculator every few kg or lb, and after a big change in training, so your calorie target keeps pace.

Under-eating protein while cutting

On the Balanced split it's easy to fall short of protein in a deficit. Switch to the High Protein preset — 0.7–1 g per pound (1.6–2.2 g/kg) helps preserve muscle when you're losing fat.

Frequently asked questions