The TDEE and macro calculators share a foundation: both estimate resting energy with the Mifflin-St Jeor equation, multiply by an activity factor, and return daily calories for adults. They diverge in what they do with those calories. The TDEE calculator reports total daily energy expenditure — maintenance calories — with mild 10% deficit and surplus targets. The macro calculator applies a lose/maintain/gain goal adjustment and splits the resulting calories into protein, fat, and carbohydrate grams. If your question is “what should the scale stay at,” use TDEE; if it is “how many grams of each macro,” use the macro calculator.
What each calculator does
The TDEE calculator takes age, sex, height in centimeters, and weight in kilograms, plus an activity level. It computes BMR with Mifflin-St Jeor, multiplies by the activity factor (sedentary 1.2, light 1.375, moderate 1.55, active 1.725, very active 1.9) for maintenance calories, and shows mild deficit = TDEE × 0.9 and mild surplus = TDEE × 1.1. All readouts round to whole calories per day. The defaults return about 2,556 kcal/day.
The macro calculator takes the same body and activity inputs plus a goal and a protein target. Calories = BMR × activity factor × goal factor (−15% for losing, +0% for maintaining, +15% for gaining). Protein grams come from the g/kg target times body weight (default 1.6 g/kg), fat is 25% of calories divided by 9, and carbs absorb the remaining calories at 4 kcal per gram for protein and carbs and 9 per gram for fat.
Side-by-side
| TDEE calculator | Macro calculator | |
|---|---|---|
| Question answered | What are my maintenance calories and mild targets around them? | What calorie goal and protein, fat, and carb grams should I plan with? |
| Core equation | BMR × activity factor | BMR × activity factor × goal factor |
| Goal handling | ±10% targets shown around maintenance | −15% / +0% / +15% applied to the calorie total |
| Primary result | Maintenance, mild deficit, mild surplus (whole kcal/day) | Daily calories plus protein, fat, and carb grams |
| Macro split | None | Protein g/kg target; fat 25% of calories; carbs as remainder |
| Extra guidance | Weight-trend test, protein calculator pairing | ACSM deficit check, ISSN protein range, DRI ranges |
When to use which
Use the TDEE calculator when the question is energy balance: how many calories a body uses in a day, and what a gentle 10% reduction or increase looks like. The page frames it as a planning number with a practical check — log intake honestly for a few weeks, and if weight stays flat, real maintenance is close to the logged intake. It suggests pairing a deficit with the protein calculator so reduced calories still contain enough protein for lean mass.
Use the macro calculator when you want gram targets: a daily calorie goal split into protein, fat, and carbs, with an adjustable protein preference. Pick the protein target by situation — around 1.4 g/kg for light training, toward 2.0 g/kg for serious muscle-building programs — and reassess every few weeks, adjusting by 100–200 kcal rather than overhauling the plan. The meal calorie calculator helps count actual meals against the gram targets.
Limits and disclaimer
Both pages are explicit that every number is an estimate: the Mifflin-St Jeor equation predicts resting energy for populations, activity multipliers are coarse conventions, individual metabolism varies by muscle mass, thyroid status, medications, illness, and training load, and tracking error in portions and labels is normal. The TDEE page warns against picking an activity factor for the person you want to be, and against treating BMR as a calorie target. Neither page is medical or nutritional advice, and neither is appropriate as a clinical plan for children, pregnancy, illness, eating disorders, or medical conditions — those call for individualized guidance from a qualified professional.