TDEE and macro calculator

What this calculator computes

It works through one chain of estimates. First it estimates your basal metabolic rate (BMR) — the energy you would burn lying still all day. Then it multiplies BMR by an activity factor to estimate total daily energy expenditure (TDEE), which is the number of calories that would keep your weight roughly stable. Finally it moves that number up or down for your goal and splits the result into protein, carbohydrate, and fat grams, either as a daily total or across 3 or 4 meals.

Every number below is an estimate from a predictive equation. None of it is a measurement, and none of it is medical advice.

The Mifflin-St Jeor equation

BMR is estimated with the Mifflin-St Jeor equation, published in 1990 in the American Journal of Clinical Nutrition and still the standard in most clinical and sports-nutrition settings:

• Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
• Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

The equation takes biological sex as a coefficient because it is predicting a physiological rate. It is not a statement about identity. Body composition matters more than the equation can see: two people with identical height, weight, age, and sex can differ by 300 kcal of resting burn if one carries substantially more lean mass.

The calculator converts imperial units for you: pounds to kilograms (1 lb = 0.4536 kg) and feet and inches to centimetres (1 in = 2.54 cm).

Activity multipliers

The activity factor is the largest source of error in the whole chain. The multipliers used here are the conventional ones:

Most people overestimate this. A workout that burns 400 kcal three times a week adds about 170 kcal per day, not a whole activity tier. If you are unsure between two levels, pick the lower one and adjust after two weeks of real data.

Calorie targets and the safe range

• Fat loss: 20% below TDEE, displayed with a 15–25% band. Moderate deficits in that range are generally easier to sustain and better at preserving lean mass than aggressive ones.
• Maintenance: TDEE with a 5% band in either direction, which is roughly the range where weight stays flat for most people.
• Muscle gain: 10% above TDEE with a 5–15% band. Larger surpluses mostly add fat.

The fat-loss calculation applies a floor of 1,500 kcal for men and 1,200 kcal for women, which are common guidance thresholds rather than universal requirements. If your TDEE is low enough that a 20% deficit would fall below the floor, the calculator raises the target and tells you why. The floor is not a recommendation to eat that little; it is a limit on how low the tool will go.

Protein, carbohydrate, and fat

Protein uses one of three settings:

• 1.2 g per kg — a maintenance-level intake for people who are not training hard.
• 1.6 g per kg — the standard setting. Controlled trials on resistance training generally show muscle protein synthesis plateauing around this intake.
• 2.2 g per kg — a high-protein setting often used during a cut, when a higher protein share helps preserve lean mass in a deficit.

Protein is capped at 40% of calories. Fat is set at 27% of calories with a floor of 0.5 g per kg, which keeps fat-soluble vitamin absorption and hormone production covered. Carbohydrate takes whatever remains.

That order matters. Protein first, fat second, carbohydrate last is the arrangement that keeps the two harder-to-hit targets intact on a fixed calorie budget.

Reading the per-meal split

Dividing evenly is a simplification, but it maps cleanly onto meal prep: one meal equals one container. Protein distribution is the figure to check. Many people do better with 25 to 40 g of protein at each sitting, and the calculator flags it when your split lands below 25 g per meal. If that happens, use 3 meals instead of 4 or make breakfast and lunch protein-heavy and dinner lighter.

Assumptions and limits

1. Predictive, not measured. Expect plus or minus 10–15% against indirect calorimetry, and wider for very muscular or very high-body-fat individuals.
2. Activity is self-reported. Non-exercise movement varies enormously between people with the same job title.
3. No medical adjustment. Thyroid conditions, medications, pregnancy, and illness all shift energy needs.
4. No body-composition tracking. The scale weight is the only input; the equation cannot tell muscle from fat.
5. Macro split is a preference, not a rule. Total calories and total protein drive most outcomes.

What to do next

1. Enter your current weight and your typical activity level, not your best week.
2. Eat at the target for 14 days without changing anything else.
3. Weigh yourself at the same time each morning and average the week.
4. If the average has not moved in the direction you want, adjust by 100–150 kcal and repeat.
5. Turn grams into food with the meal prep portions calculator and scale recipes with the batch cooking scaler.

What this tool cannot do

It cannot measure your metabolism, diagnose anything, or tell you whether a calorie target is appropriate for a medical condition. It does not account for pregnancy, lactation, eating disorders, diabetes, kidney disease, or medication effects. Take the output to a registered dietitian if any of those apply, or if the numbers do not match what your body is actually doing.