Free Macro Calculator — Protein, Carbs & Fat Grams (AMDR-Based) (2026)
Get your daily protein, carb, and fat grams from your TDEE across three splits — anchored to the Institute of Medicine AMDRs, with the ranges shown instead of hidden. Free, no signup.
Macros are your calories with a job description: protein for tissue, carbohydrate for fuel, fat for hormones and absorption. Enter five details and get gram targets across three splits — each positioned against the Institute of Medicine's acceptable ranges, not invented ratios.
How the splits are built
The Institute of Medicine's Acceptable Macronutrient Distribution Ranges put protein at 10–35% of energy, carbohydrate at 45–65%, and fat at 20–35%. The three splits above sit inside those ranges — balanced in the middle, higher-protein favoring satiety and muscle retention.
The lower-carb split deliberately sits below the carbohydrate AMDR floor — a popular pattern we'd rather show honestly, with a label, than pretend doesn't exist. Grams use the standard 4/4/9 kcal-per-gram conversions.
Which split should you pick?
Adherence beats optimization: the best split is the one whose meals you'll actually keep eating. Protein is the macro with the strongest evidence for being deliberate — it preserves lean mass in a deficit and is the most satiating per calorie.
Carbs and fat are largely an energy-preference trade within the ranges. Athletes with high training volume usually feel better toward the carb ceiling; people who satiate on fat often prefer the other direction. Both work at equal calories.
Formula & sources
Grams per macronutrient
The 4/4/9 Atwater factors. Percentages are of total daily energy.
Acceptable Macronutrient Distribution Ranges (AMDR)
IOM reference ranges, as % of energy.
| Macronutrient | % of energy |
|---|---|
| Protein | 10–35% |
| Carbohydrate | 45–65% |
| Fat | 20–35% |
Sources
- Institute of Medicine (2005) Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids — Atwater factors and the AMDRs.
Macro questions, answered
What macros should I eat to lose weight?
Weight change is set by calories; macros set how the change feels and what it's made of. In a deficit, prioritize the protein end of the ranges (25–30% of energy) to protect muscle and manage hunger, then split the remainder between carbs and fat by preference.
How many grams of protein, carbs, and fat do I need?
At maintenance, the balanced split gives most adults roughly 1.6–2.2 g protein per kg only at high percentages — this page shows your exact grams for each split at your calories, which beats any generic rule of thumb.
Are these splits inside official guidelines?
Balanced and higher-protein sit fully inside the IOM AMDRs. Lower-carb sits below the 45% carbohydrate floor and is labeled as such — popular, but outside the reference range by design.
Do I need to hit macros exactly?
No. Daily ±10 g noise is irrelevant. Weekly averages near the targets — with protein the one you track most closely — deliver everything the precision theater does, with far less burnout.
Why grams instead of percentages?
You can't eat a percentage. Grams map to food labels and portions; that's also why the next step here is a plate: the MyPlate Plan converts the same calories into food groups you can actually shop for.
Do these macros change if I'm cutting or bulking?
The percentages can stay; the calories change. Set your target with the calorie-deficit calculator (or add a modest surplus), then apply the same split to that number — protein in absolute grams should stay high while cutting.