How the macro calculator works
The calculator adjusts your maintenance calories for your goal, sets protein from body weight, sets fat as a share of calories and gives the rest to carbohydrates.
Protein g = body weight (lb) × g per lb · 4 kcal/g
Fat g = calories × fat % ÷ 9
Carbs g = (calories − protein kcal − fat kcal) ÷ 4
A 20% deficit typically produces about 0.5% to 1% of body weight lost per week. Research reviewed by the International Society of Sports Nutrition supports 1.4 to 2.0 g of protein per kg (about 0.7 to 1.0 g per lb) for active people, with the higher end useful during a deficit to preserve muscle. Keeping fat at 20% or more of calories supports hormone health and the absorption of fat-soluble vitamins.
Worked example
A 170 lb person with a 2,500 kcal TDEE wants to lose fat. Calories become 2,000 kcal. Protein at 0.8 g/lb is 136 g (544 kcal), fat at 25% is 500 kcal or 56 g, and the remaining 956 kcal give 239 g of carbohydrates. For muscle gain the same person would eat 2,750 kcal with 136 g protein, 76 g fat and 380 g carbs.
Frequently asked questions
How much protein do I need?
The RDA is 0.8 g per kg for sedentary adults. For people who train, 1.4 to 2.0 g per kg (0.64 to 0.9 g per lb) is a common evidence-based range.
What macro ratio is best for fat loss?
Total calories drive fat loss. Within that, higher protein helps preserve muscle and keep you full; the carb and fat split matters less for most people.
Should I count fiber in carbs?
Nutrition labels in the US include fiber in total carbohydrate. Counting total carbs is simplest and matches this calculator.
How many calories are in each macro?
Protein and carbohydrate have about 4 kcal per gram, fat about 9 and alcohol about 7.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.