How this calculator works
Protein grams = body weight in kg × chosen g/kg/day. Fat grams = calories × fat percentage / 900. Carbohydrate grams = (calories − 4 × protein grams − 9 × fat grams) / 4.
ISSN describes 1.4–2.0 g/kg/day as sufficient for most exercising individuals. The 1.6 example is an illustrative choice within that range. The tool also allows 0.8–1.4; higher athletic intakes and clinical needs require a different assessment. The ratio stays in g/kg even with pound display units.
General adult reference ranges allocate 20–35% of energy to fat, 10–35% to protein, and 45–65% to carbohydrate. Fat stays within that range here; protein and carbohydrate allocations outside their ranges receive a visible note. Protein plus fat above the calorie target is rejected.
Reading your result
This is an allocation of an existing calorie target, not a diet or food plan. Calculations retain full precision and displayed grams round to two decimals, so displayed totals may differ by a fraction of a kcal. The general 4/9/4 energy factors do not reproduce every food label exactly.
Illustrative worked example
At 2,400 kcal/day and 70 kg, choosing 1.6 g/kg protein and 30% fat produces 112 g protein, 80 g fat and 308 g carbohydrate: 448 + 720 + 1,232 = 2,400 kcal.
Supported inputs & limitations
For generally healthy adults 20–100 without pregnancy, breastfeeding or clinical nutrition needs. Targets 1,500–5,000 kcal/day and weight 30–300 kg are tool boundaries, not a personalized recommendation. Macronutrient arithmetic cannot confirm adequate vitamins, minerals, essential fats or fiber.
Sources & methodology
These primary sources support the method and context. They do not endorse helsi or verify this implementation.