Macro Calculator
Turn your daily calories into protein, carb and fat targets in grams — balanced, low fat, low carb, high protein, or a split you build yourself.
BMR estimation formula
Katch-McArdle works from lean mass, so it needs your body fat percentage. If you do not know it, the body fat calculator will estimate it from a tape measure.
Ranges come from the accepted intake bands: protein from 1 g per kg of body weight up to 35% of energy, carbohydrate 40–65%, fat 20–35%. Sugar and saturated fat are each capped at 10% of energy.
| Plan | Protein | Carbs | Fat |
|---|
Percentages of total energy. Every split adds to 100% and lands on the same calorie total — they differ in how that total is divided, not in how much you eat.
| Macronutrient | Calories per gram |
|---|---|
| Protein | 4.1 |
| Carbohydrate | 3.75 |
| Fat | 8.8 |
| Alcohol | 7.0 |
These are Atwater specific factors, slightly different from the 4/4/9 shorthand most labels use. They are what this calculator applies, which is why a gram figure here can differ by a percent or two from a tool using the rounder numbers.
What macros are, and what they are not
Three nutrients supply the energy your body runs on: protein, carbohydrate and fat. Everything else you eat — vitamins, minerals, fibre, water — is essential in its own way but contributes no usable calories. That is the whole of what "macros" means, and the reason a diet can be described completely by three numbers.
Protein supplies amino acids for building and repairing tissue, and it is the macro your body is least willing to improvise around. Carbohydrate is the fuel your muscles and brain reach for first, and the one most easily adjusted up or down without harm. Fat is structural as well as energetic — hormones and cell membranes depend on it — and it is the most energy-dense of the three, which is why small changes in fat intake move a calorie total quickly.
What macros are not is a measure of food quality. A day of chicken, rice and olive oil and a day of protein bars, soda and butter can hit identical numbers. The split tells you the shape of a diet, not whether it is a good one.
How this calculator works
Three steps. The macro calculator estimates your resting metabolic rate, multiplies by your activity level and applies your weight goal to reach a daily calorie total, then divides that total into grams.
BMR × activity multiplier + goal adjustment
Mifflin St Jeor by default, Katch-McArdle if you know your body fat
Step 2 — split the energy
protein grams = energy × share ÷ 4.1
carb grams = energy × share ÷ 3.75
fat grams = energy × share ÷ 8.8
Those divisors are the Atwater specific factors rather than the familiar 4/4/9. They account for the fact that none of the three is perfectly absorbed, and they are what this calculator applies throughout — which is why a figure here can sit a percent or two away from a tool using round numbers.
Running the page defaults through it — a 25-year-old man, 5′10″, 165 lb, training four or five times a week, maintaining weight — gives 2,549 Calories a day. Split the balanced way, that is 155 g of protein, 340 g of carbohydrate and 72 g of fat.
Two limits sit on top of the split. Sugar and saturated fat are each capped at 10% of energy, following WHO and Dietary Guidelines advice. Both are ceilings inside the totals above, not additions to them.
Choosing between the four splits
Every split produces the same calorie total. They differ only in how it is divided, which is worth remembering before agonising over the choice.
- Balanced (25 / 50 / 25) — the default, and a sensible starting point for most people with no particular constraint.
- Low Fat (27.5 / 52.5 / 20) — drops fat to the bottom of the accepted range and moves the energy into carbohydrate and protein. Suits high-volume endurance training.
- Low Carb (30 / 40 / 30) — pulls carbohydrate to its floor. Useful for people managing blood sugar, or who simply find they eat better this way.
- High Protein (35 / 42.5 / 22.5) — the one to pick in a calorie deficit or while building muscle, because protein is what protects lean mass when energy is short.
Create Your Own opens three sliders if none of the four fits. Keep the three percentages adding to 100 and the grams will match your calorie total; the note under the sliders tells you when they do not.
Reading the ranges rather than the single number
Each macro shows a range beside its figure, and the range carries more information than the number.
Protein runs from 1 gram per kilogram of body weight up to 35% of energy. The floor is tied to your body rather than your calories, because protein needs scale with the tissue being maintained, not with how much you happen to be eating. Carbohydrate runs from 40% of energy up to whatever is left once protein and fat are at their minimums. Fat runs from 20% to 35% of energy — the lower bound matters, since going far below it interferes with hormone production and the absorption of fat-soluble vitamins.
Anywhere inside those bands is defensible. The single figure is one point in a wide space, and treating it as a precise requirement gives a calorie estimate more authority than it has earned.
Hitting macros in practice
Whatever a macro calculator hands you, protein is the one to plan around, because it is the hardest to reach by accident and the one with the clearest consequence for missing it. Build meals from a protein source outward and the other two tend to fall into place.
Precision matters less than most tracking apps imply. Landing within about ten grams on protein and fat, and twenty on carbohydrate, is close enough — the calorie total underneath carries roughly 10% uncertainty, so chasing single grams is precision applied to an estimate that cannot support it.
Consistency over weeks is what actually decides the outcome. Track for two or three weeks, watch your weight trend, and adjust the calorie total if reality disagrees with the arithmetic. That correction is worth far more than any refinement of the split.
What this calculator does not cover
- Food quality. Identical macros can come from very different diets. Fibre, micronutrients and how processed the food is are all invisible here.
- Fibre. It sits inside the carbohydrate total and has its own guidance — roughly 25 to 38 grams a day — which this does not report.
- Anyone outside 18 to 80. The calorie equations underneath were built on working-age adults, so the tool refuses ages either side rather than stretching a curve past its evidence.
- Pregnancy and nursing. Both protein and energy requirements climb on their own schedule, governed by guidance this page makes no attempt to reproduce.
- Medical conditions. Kidney disease, diabetes and several other conditions place real constraints on macro intake that override anything here.
- Sport-specific needs. Endurance and strength athletes at high volume often need more than these ranges suggest, and are better served by a sports dietitian.
Either side of this page sit its neighbours: the TDEE calculator goes deeper on where the calorie total comes from, and the protein, carbohydrate and fat intake calculators each take one macro further.
Frequently asked questions
What are macros, exactly?
Protein, carbohydrate and fat — the three nutrients your body needs in gram quantities and the only ones that supply energy. Vitamins and minerals are micronutrients, needed in milligrams. Alcohol also carries calories but is not counted as a macronutrient. Everything you eat breaks down into these three plus water, fibre and micronutrients.
How many grams of protein should I eat a day?
This calculator shows a range rather than one figure. The floor is 1 gram per kilogram of body weight, and the ceiling is 35% of your daily energy. Where you sit inside that depends on what you are doing: the higher end suits someone training hard or eating in a deficit, since protein protects lean mass when calories are short.
Which macro split is best?
For most people the split matters far less than hitting the calorie total and getting enough protein. Balanced at 25/50/25 is a reasonable default. Low carb suits people who prefer it or manage blood sugar; high protein suits anyone in a deficit or building muscle. All four splits on this page produce the same daily calories — they only divide it differently.
Why does this calculator use 4.1, 3.75 and 8.8 calories per gram?
Those are the Atwater specific factors, which are slightly more precise than the 4/4/9 shorthand on food labels. Protein and carbohydrate are not perfectly absorbed, so their usable energy is a little under 4, while fat comes in a little under 9. The difference is small — a percent or two on a daily total — but it is why a gram figure here can differ slightly from a tool using round numbers.
Do I have to hit my macros exactly?
No, and treating them as exact targets is usually counterproductive. They are a guide with real uncertainty baked in: the calorie total behind them is an estimate with roughly 10% error, and daily expenditure varies anyway. Landing within about ten grams of protein and fat and twenty of carbohydrate is close enough for the plan to work.
What are the sugar and saturated fat limits?
Both are capped at 10% of daily energy, following World Health Organization and Dietary Guidelines advice. They are ceilings rather than targets — there is no requirement to eat any added sugar at all. Note that the sugar figure sits inside your carbohydrate total and the saturated fat inside your fat total; they are not extra.
Should the split change if I am losing weight?
Protein is the one worth raising. In a calorie deficit the body will draw on lean tissue as well as fat, and a higher protein intake alongside resistance training limits how much muscle goes. The high-protein split on this page is built for exactly that. Carbohydrate and fat can then be divided however you find easiest to stick to.
Does the timing of my macros matter?
Much less than the daily totals. Spreading protein across three or four meals is mildly better for muscle than loading it into one, and eating carbohydrate around training is convenient if you train hard. Beyond that, meal timing is a rounding error next to consistently hitting your numbers over weeks.
Treat these gram targets as teaching material, not instruction. Nothing on this page has been reviewed for your circumstances, stands in for a professional opinion, or identifies a condition — and the calorie figure the grams are cut from is an approximation to begin with, so the precision they appear to offer is borrowed. Run them past a physician or registered dietitian before you build meals around them. That request is firmer than usual if you are expecting or feeding an infant, if you are younger than 18, if kidney disease, diabetes or any comparable diagnosis is in the picture, or if counting what you eat has ever become difficult to stop. Learn more about how we build these tools or read our privacy policy.