What This Calculator Does

Estimate adult BMR and TDEE from age, sex-based formula, height, weight and activity. Retain the fixed daily ±500 kcal references. Choose TDEE, a loss/gain reference or your own calorie amount, then convert editable protein, fat and carbohydrate calorie percentages to daily grams.

When to Use It

Use it for general adult planning and scenario comparisons. Compare formulas with BMR or inspect weight-based protein examples with protein. These estimates are not individualized nutrition prescriptions.

Inputs Explained

Whole age 18–100, height 100–250 cm and weight 30–300 kg. Choose male or female formula and an activity factor of 1.2, 1.375, 1.55, 1.725 or 1.9. All three macro percentages are editable, each 0–100%, totaling 100%. Default 30/30/40 is an example, not a recommended target. Percentages are energy shares, not shares of gram weight. Custom calories must be positive and at most 10000 kcal; this custom-input limit does not reject TDEE from valid body inputs. Within the accepted range, maximum TDEE is 10076.84 kcal and its gain reference 10576.84 kcal; both still support macro conversion. These software bounds are not safe-intake recommendations.

How the Calculation Works

The existing original Harris–Benedict coefficients remain: male BMR = 66 + 13.7W + 5H − 6.8A; female BMR = 655 + 9.6W + 1.8H − 4.7A, with W in kg, H in cm and A in years. TDEE = BMR×activity factor. Loss/gain references subtract/add 500 kcal; that fixed adjustment is not appropriate for everyone. Macro grams = calories×percentage/100/energy factor, using 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat.

Example

Male, age 30, 170 cm, 65 kg and activity 1.2 gives BMR 1602.5 and TDEE 1923 kcal/day. Fixed references are 1423 and 2423. Select custom 2000 kcal with 30% protein, 30% fat and 40% carbohydrate: 150 g protein, about 66.7 g fat and 200 g carbohydrate. The 4/9/4 conversion reconstructs 2000 kcal.