Free macros calculator
Turn a calorie target into grams in one step. Enter your daily calories and pick a protein / carbs / fat split — the macro calculator returns the grams of each to eat per day using the 4/4/9 rule, updated live, as you type.
On this page15 sections
Protein/carbs = 4 kcal/g; fat = 9 kcal/g. Percentages should total 100%.
Results are estimates. Consult a professional.
What are macros (macronutrients)?
"Macros" is short for macronutrients — the three nutrients your body needs in large amounts because they supply all of your energy: protein, carbohydrate, and fat. Every calorie you eat comes from one of them (alcohol aside). A macro calculator takes your daily calorie target and a chosen ratio and tells you how many grams of each to eat — which is exactly what the calculator above does the moment you set your calories and split.
Counting calories tells you how much to eat; counting macros tells you what kind of food those calories come from. Two 2,000-calorie days can look completely different — one protein-forward and filling, one carb-heavy and not — and that difference is what macros capture. Hitting your protein target protects muscle, your fat target supports hormones, and your carbs fuel training.
The 4/4/9 rule: how calories convert to grams
All macro math runs on one set of numbers — the Atwater energy values. Each gram of a macronutrient carries a fixed number of calories: protein and carbohydrate are 4 calories per gram, and fat is 9. Fat packs more than double the energy of the other two, which is why a small change in fat grams moves your calories so much.
So to turn a split into grams you take your calorie target, multiply by each macro's percentage, then divide by its calories-per-gram. On a 2,000-calorie day at 30% protein / 40% carbs / 30% fat: protein = 2,000 × 0.30 ÷ 4 = 150 g, carbs = 2,000 × 0.40 ÷ 4 = 200 g, fat = 2,000 × 0.30 ÷ 9 = 67 g. That is what the worked example below walks through step by step.
How to set your macro split
Setting macros is a four-step process. The first step happens off this page — you need a calorie target — and the last three are what the calculator turns into grams.
- Start with your calorie target. Get this from the calorie calculator or your TDEE, adjusted for whether you want to lose, maintain, or gain.
- Set protein first. Protein is the macro to anchor — aim high enough to protect muscle (more on the gram targets below). Most people land between 25% and 40% of calories.
- Choose carbs and fat to fill the rest. Whatever calories remain after protein get split between carbs and fat to taste — more carbs if you train hard, more fat if you prefer it or are eating lower-carb.
- Convert to grams. Enter your calories and the three percentages and the calculator returns the grams to eat each day.
Common macro split ratios compared
There is no universal macro ratio — there are a handful of common ones, each suited to a different goal. The table shows the popular splits as protein / carbs / fat percentages, so you can pick a starting point and adjust from there.
| Split | Protein | Carbs | Fat | Best for |
|---|---|---|---|---|
| Balanced (the default) | 30% | 40% | 30% | General health, maintenance, beginners |
| High-protein | 40% | 30% | 30% | Fat loss, preserving muscle in a cut |
| Low-carb | 30% | 20% | 50% | Lower-carb eaters, appetite control |
| Higher-carb (endurance) | 25% | 55% | 20% | Endurance athletes, heavy training volume |
| Keto | 20% | 5% | 75% | Ketosis — a distinct method (see below) |
Percentages of total calories, ordered protein / carbs / fat. The 30/40/30 balanced split is this calculator's default starting point.
The USDA and Institute of Medicine give official ranges to stay within: 45–65% of calories from carbs, 10–35% from protein, and 20–35% from fat — the Acceptable Macronutrient Distribution Ranges (AMDR). Keto sits deliberately outside them; if that's your goal, the keto calculator handles its very different mechanics, where carbs are fixed low and fat fills the rest.
A worked example using the macro calculator
Alex eats around 2,000 calories a day and wants a balanced split — 30% protein, 40% carbs, 30% fat, the calculator's default. Here is the arithmetic the calculator runs to turn that into grams, one macro at a time.
Step 1 — Protein (4 cal/g)
Protein is 30% of 2,000 calories = 600 calories. At 4 calories per gram: 600 ÷ 4 = 150 g protein.
Step 2 — Carbs (4 cal/g)
Carbs are 40% of 2,000 = 800 calories. At 4 calories per gram: 800 ÷ 4 = 200 g carbs.
Step 3 — Fat (9 cal/g)
Fat is 30% of 2,000 = 600 calories. At 9 calories per gram: 600 ÷ 9 = 67 g fat (66.7 g, rounded).
| Macro | % of calories | Calories | Grams/day |
|---|---|---|---|
| Protein | 30% | 600 | 150 g |
| Carbs | 40% | 800 | 200 g |
| Fat | 30% | 600 | 67 g |
| Total | 100% | 2,000 | — |
Alex's macros at 2,000 calories on a 30/40/30 split — the literal output of the calculator above.
Macros for cutting, maintaining, and bulking
Your goal changes two things: your calorie target (set elsewhere) and your split. The pattern across all three goals is the same — keep protein high, then shift carbs and fat around it. The table shows typical starting splits.
| Goal | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| Cut (fat loss) | Below maintenance | 35–40% | 25–35% | 25–30% |
| Maintain | At maintenance | 25–30% | 40–50% | 25–30% |
| Bulk (muscle gain) | Above maintenance | 25–30% | 45–55% | 20–25% |
Typical starting splits. Note protein's share is highest on a cut — because a deficit threatens muscle, and protein protects it.
- Cutting — protein goes up (as a share of fewer calories) to defend muscle, while carbs and fat both come down. The deficit drives the fat loss; the high protein keeps it muscle-sparing.
- Maintaining — a balanced split at maintenance calories holds your weight and supports training. This is the easiest split to sustain long-term.
- Bulking — extra calories go mostly to carbs to fuel hard training and recovery, with protein steady and fat moderate. The surplus drives growth; carbs power the work that earns it.
In every case, calories decide the direction (lose, hold, or gain) and macros shape the result. Pair this with the calorie calculator to set the target your split divides up.
How much protein should you eat?
Protein is the macro to set first and hit most consistently — it preserves muscle, keeps you full, and is the hardest for the body to store as fat. Targets are usually given per unit of bodyweight, not as a flat percentage, because that scales to your size.
- 0.8 g per kg (0.36 g/lb) — the RDA, the minimum to prevent deficiency. Enough to survive, not to build.
- 1.2–1.6 g/kg (0.5–0.7 g/lb) — a solid target for general health and active people not chasing muscle.
- 1.6–2.2 g/kg (0.7–1.0 g/lb) — the range research links to building and keeping muscle, and the one to use in a cut.
A common rule of thumb is 1 gram of protein per pound of bodyweight when training hard or dieting — it sits at the top of the evidence-based range and is easy to remember. For a dedicated bodyweight-based target, use the protein calculator; to convert your chosen percentage into grams, the macro calculator above does it.
IIFYM and flexible dieting explained
Macro counting is the engine behind IIFYM — "If It Fits Your Macros" — also called flexible dieting. The idea: no food is off-limits as long as it fits inside your daily protein, carb, and fat targets. A square of chocolate that fits your remaining macros is allowed; the focus is on hitting the numbers, not on "clean" versus "dirty" foods.
Compared with a rigid meal plan, flexible dieting trades a fixed menu for a budget. That makes it easier to stick to — you can eat out, fit in a treat, and adapt to your life — because you're working toward three numbers rather than a forbidden-foods list. The trade-off is that you do have to track, at least until portions become second nature.
Where does fiber fit in?
Fiber is a type of carbohydrate, so it's already inside your carb macro — it isn't a fourth number to hit on top of protein, carbs, and fat. But it's worth tracking on its own because it does so much per calorie: it slows digestion, keeps you full, feeds gut bacteria, and steadies blood sugar.
A common target is about 14 grams of fiber per 1,000 calories — roughly 25 g a day for women and 38 g for men. Hit your carb macro mostly from vegetables, fruit, legumes, and whole grains and the fiber largely takes care of itself. (Low-carb and keto eaters track fiber differently, as net carbs.)
How to track your macros
Knowing your gram targets is half the job; hitting them consistently is the other half. A few habits do most of the work:
- Weigh your food on a digital scale. Grams beat guesswork — eyeballing portions is where most tracking errors come from, especially with calorie-dense fats.
- Use a tracking app. Log meals in MyFitnessPal, Cronometer, or similar; they tally your protein, carbs, and fat against your targets as you go.
- Hit protein first. Protein is the target to nail every day. Build each meal around a protein source and the rest of the split falls into place more easily.
- Aim within 5–10 grams of each target. You don't need to be exact to the gram. Landing within a small margin, day after day, is what drives results.
- Recalculate as your weight changes. Your calorie target shifts as you lose or gain, so re-run the numbers every few kilos and re-split rather than holding an old target.
Data sources and methodology
This calculator converts a calorie target and a percentage split into grams using the Atwater energy values — 4 kcal/g for protein and carbohydrate, 9 kcal/g for fat. The official intake ranges (45–65% carbs, 10–35% protein, 20–35% fat) are the Acceptable Macronutrient Distribution Ranges from the US Institute of Medicine / USDA Dietary Guidelines. Protein-per-bodyweight targets follow the International Society of Sports Nutrition (ISSN) position stand on protein and exercise. All math runs in your browser — nothing you enter is stored or shared.
USDA & HHS. Dietary Guidelines for Americans, 2020–2025 — Acceptable Macronutrient Distribution Ranges.Jäger R, Kerksick CM, et al. ISSN Position Stand: Protein and Exercise. J Int Soc Sports Nutr, 2017.Frequently asked questions about the free macros calculator
About this macro calculator
This macro calculator runs entirely in your browser. The numbers you enter stay on your device — nothing is sent to a server, logged, or shared. It converts your calorie target and chosen protein/carbs/fat split into daily grams using the Atwater energy values (4 calories per gram of protein and carbs, 9 per gram of fat), updating instantly as you type.
Calculators Cloud offers 400+ free tools with no sign-up. The whole Health calculators shelf includes Calorie, TDEE, Protein, Carbohydrate, and Keto tools alongside this one. Or browse the full calculator directory.