Macro Calculator

What Are Macronutrients?

Only three things in food supply energy, and nutrition science calls them macronutrients because you eat them in grams rather than milligrams. Carbohydrate and protein release about 4 calories per gram, fat about 9. Those three numbers — the Atwater general factors, published by the FAO — are the entire bridge between a calorie target and a shopping list.

A macro split is simply how you divide a calorie total among the three. Say it as percentages of energy, and the grams follow automatically. This page's split is 40 percent carbohydrate, 30 percent protein, 30 percent fat, applied to whatever calorie figure your body and activity level produce.

Alcohol contributes 7 calories per gram and is sometimes called a fourth macronutrient, but it is not part of any split here and the calculator has no field for it. If you drink, those calories sit on top of the total the tool returns.

What Each Macro Actually Does

The three are not interchangeable fuel. Each has a floor set by physiology, and those floors are far below what an active person eats.

Set those floors against what the calculator hands the reference man at 2,556 calories: 256 g carbohydrate, 192 g protein, 85 g fat. His protein target is 3.4 times the RDA and his carbohydrate target is roughly twice it. That gap is the whole point of a macro split — it is a performance and body-composition tool, not a deficiency-prevention tool.

• Carbohydrate is the fuel your brain and hard training draw on first. The 2005 Dietary Reference Intakes set its RDA at 130 g a day for adults — an amount based on the glucose the brain uses, not on athletic need.
• Protein supplies the amino acids that rebuild muscle, skin, enzymes, and hormones. Its RDA is 56 g a day for men aged 19 to 30 and 46 g for women, which is a floor for avoiding deficiency rather than a target for training.
• Fat carries the fat-soluble vitamins, supplies essential fatty acids, and underpins hormone production. It has no RDA at all — the same DRI tables list total fat as "not determined" for adults, because requirement varies too much to pin down.

At 40 percent of calories, carbohydrate only falls below the 130 g RDA if your daily total drops under 1,300 calories. Nobody using this page at a sensible calorie level is at risk of undershooting the brain's requirement.

Macros vs Calories: What the Split Adds

A calorie figure tells you how much to eat. A macro split tells you what shape that food takes, and the shape matters most at the protein line, because protein is the macro whose intake changes what the weight you lose or gain is made of.

The arithmetic is one-directional: macros are derived from calories, never the reverse. Change your calorie total and every gram target moves with it. Drop the reference man from 2,556 to 2,056 calories — a 500-calorie deficit — and his split becomes 206 g carbohydrate, 154 g protein, 69 g fat, a loss of 50 g of carbohydrate, 38 g of protein, and 17 g of fat from the maintenance figures.

If you want the calorie total on its own first, with five different resting-metabolism equations to compare rather than one, run your numbers through the TDEE Calculator.

That is worth noticing before you diet on a percentage split. Cutting calories on a fixed 30 percent protein cuts protein too, at exactly the moment protein matters most. The fix is arithmetic, not a different tool, and the section on reading your result shows it.

How Do You Calculate Your Macros?

Two steps, and the calculator does both. Step one estimates your daily calories from your body and your activity level. Step two multiplies that total by each macro's percentage and divides by its calories per gram.

Grams of a macro = (daily calories × macro percentage) ÷ calories per gram

The Macro Formula, Written Out

Written in full, with the fixed percentages and energy factors this page uses, the whole calculation is five lines.

Men:   calories = (10 × weight in kg + 6.25 × height in cm − 5 × age + 5) × activity factor

Women: calories = (10 × weight in kg + 6.25 × height in cm − 5 × age − 161) × activity factor

Carbohydrate (g) = (calories × 0.40) ÷ 4

Protein (g)      = (calories × 0.30) ÷ 4

Fat (g)          = (calories × 0.30) ÷ 9

The equations expect metric units. Enter inches, feet, or pounds and the calculator converts before anything else happens — an inch becomes 2.54 cm, a pound becomes 0.453592 kg — so the arithmetic above is always what runs underneath.

Everything is rounded once, at the end. Calories round to a whole number and each macro rounds to a whole gram, which is why the grams do not always re-add to the calorie figure exactly. More on that residue in the limits section.

Step by Step

The form asks eight questions. Five of them change the answer; two are unit selectors that only change how your entry is read, and the Goal field changes nothing at all.

Press Calculate and the readout returns four figures on one line: calories, then carbohydrate, protein, and fat in grams. There is no meal plan, no food list, and no adjustment for a deficit or a surplus — every one of those is something you do to the numbers afterward.

• Choose Male or Female. Mifflin-St Jeor carries a different constant for each: +5 against −161.
• Enter your age in whole years.
• Choose your height unit: cm, inch, or Feet.Inches.
• Enter your height in the unit you just chose.
• Choose your weight unit: kg or pounds.
• Enter your weight in the unit you just chose.
• Choose the activity level that matches your typical week, not your best week.
• Choose a Goal. This field is offered but does not alter the result — see the section on using the calculator.

Worked Example: 30-Year-Old Man, 175 cm, 70 kg

Male, 30 years, 175 cm, 70 kg, moderate exercise 2 to 3 times a week, which is the 1.55 multiplier.

BMR = (10 × 70) + (6.25 × 175) − (5 × 30) + 5 = 1,648.75 kcal/day

Calories = 1,648.75 × 1.55 = 2,555.56 → 2,556 kcal/day

Carbohydrate = (2,555.56 × 0.40) ÷ 4 = 255.56 → 256 g

Protein      = (2,555.56 × 0.30) ÷ 4 = 191.67 → 192 g

Fat          = (2,555.56 × 0.30) ÷ 9 = 85.19 → 85 g

Result at the moderate setting

2,556 kcal — 256 g carbs, 192 g protein, 85 g fat

Change nothing but the activity dropdown and the grams move a long way. Sedentary gives him 1,979 calories with 198 g carbohydrate, 148 g protein, and 66 g fat. The professional-athlete setting gives 3,298 calories with 330 g carbohydrate, 247 g protein, and 110 g fat — 99 g more protein a day than the sedentary row, from a field that describes his schedule rather than his body.

Worked Example: 35-Year-Old Woman, 165 cm, 65 kg

Female, 35 years, 165 cm, 65 kg, light exercise 1 to 2 times a week, the 1.375 multiplier.

BMR = (10 × 65) + (6.25 × 165) − (5 × 35) − 161 = 1,345.25 kcal/day

Calories = 1,345.25 × 1.375 = 1,849.72 → 1,850 kcal/day

Carbohydrate = 185 g, Protein = 139 g, Fat = 62 g

Result at the light-exercise setting

1,850 kcal — 185 g carbs, 139 g protein, 62 g fat

Her six settings run 1,614, 1,850, 2,085, 2,321, 2,556, and 2,691 calories. Note the fifth: at the physical-job multiplier she lands on 2,556 calories and therefore on exactly the same 256 g, 192 g, 85 g the reference man gets at moderate exercise. Two different bodies, identical gram targets — and on her 65 kg frame that 192 g of protein is 2.95 g per kilogram against his 2.74.

Entering Feet, Inches, and Pounds

The Feet.Inches option reads the digits after the decimal point as whole inches, not as a fraction of a foot. It is the most common way to get a wrong answer out of this page.

Every row above is a 30-year-old man at 70 kg on the moderate multiplier. Typing 5.1 when you meant five foot ten costs 221 calories and 22 g of carbohydrate a day. Keep the trailing zero, or pick cm or inch and avoid the question. Inches above 11 are clamped rather than carried into another foot, so 5.12 does not become 6 ft 0 in.

The weight selector has a quieter version of the same trap. Enter 154 while the selector still reads kg and the same man is handed 3,858 calories with 386 g carbohydrate, 289 g protein, and 129 g fat — half again as much food as he needs, from one untouched button.

Set correctly, the units agree with each other. Feet.Inches 5.9 with 154 pounds returns 2,556 calories and 256 / 192 / 85 g, the same as 175 cm with 70 kg, because 5 ft 9 in is 175.26 cm and 154 lb is 69.85 kg.

Macro Chart: Grams by Body and Activity Level

Every figure below came from running this calculator. The reference man — 30 years, 175 cm, 70 kg — is used throughout so that one variable moves at a time. Find the row nearest your own build to see the range you are working inside before you enter anything.

Read the last column rather than the first. His body weight never changes across those six rows, yet the protein target climbs from 2.12 to 3.53 g per kilogram. That is a consequence of splitting by percentage of calories, and it is the single most useful thing this chart shows.

Four Bodies at Every Activity Setting

Each cell is carbohydrate / protein / fat in grams, at the setting in the column header. These are illustrative bodies, not population averages.

The narrowest column is the leftmost. Sedentary, the four profiles differ by 58 g of carbohydrate between highest and lowest (217 g against 158 g); at the athlete setting the same four differ by 97 g (361 g against 264 g). The multiplier magnifies the differences between bodies as well as raising the totals.

One row deserves a second look. The 45-year-old woman at 75 kg gets 147 g of protein at the light setting — 1.96 g per kilogram, comfortably inside the range sports-nutrition guidance supports. The 30-year-old woman at 60 kg gets 198 g at the athlete setting, which on her frame is 3.30 g per kilogram. Same split, very different prescriptions.

How Much Each Field Moves the Grams

Changing one field at a time on the reference man, holding the moderate multiplier, prices each measurement.

Forty years of aging removes 23 g of protein a day from his target. One step up the activity dropdown adds 22 g. A field nobody can measure is worth almost as much as four decades of a field everybody can.

The sex constant is larger than it looks. Identical height, weight, and age, male against female, is a 257-calorie gap and 19 g of protein — entirely from the +5 and −161 constants inside Mifflin-St Jeor.

Splits Other Than 40/30/30

The calculator returns one split and only one. The table below applies other ratios to the reference man's calorie total — 2,555.56, the unrounded figure behind the displayed 2,556 — using the same 4/4/9 energy factors, so you can see what a different ratio would mean in grams before you decide to follow one.

The high-protein row is the one to be careful with. At maintenance calories, 40 percent protein means 256 g for a 70 kg man — 3.65 g per kilogram, above even the 2.3 to 3.1 g/kg band the International Society of Sports Nutrition describes for retaining lean mass while dieting. The same 30/40/30 ratio applied to a 20 percent deficit, 2,044 calories, gives 204 g, or 2.92 g per kilogram, which lands inside it. A protein-heavy split is a cutting split; run it at maintenance and the number stops making sense.

The endurance row moves in the opposite direction: 351 g of carbohydrate and only 128 g of protein, 1.83 g per kilogram. That is still above the 1.4 g/kg lower bound for exercising people, which is why an endurance-shaped split can afford to give so much of the plate to carbohydrate.

For carbohydrate set on its own rather than as a leftover percentage, including lower-carbohydrate and ketogenic patterns this split cannot produce, use the Carb Calculator.

Using the Free Macro Calculator Online

The tool at the top of this page is free, needs no sign-in, and runs entirely in your browser — nothing you type is sent anywhere. Eight fields in, four numbers out.

Three fields open blank: age, height, and weight. The five selectors start on their first option — Male, cm, kg, the sedentary 1.2 multiplier, and Maintain Weight — so if you fill in your measurements and press Calculate without touching anything else, you get the sedentary answer. That is the most common reason a first result looks low.

• Gender — Male or Female
• Age — in whole years
• Height Unit — cm, inch, or Feet.Inches
• Height — in the unit selected
• Weight Unit — kg or pounds
• Weight — in the unit selected
• Activity Level — six settings from 1.2 to 2.0
• Goal — Maintain Weight or Change Weight

Run it more than once. Calculate at the multiplier you believe, then again one step either side, and you have the band your true targets sit inside. For the reference man that band is 227 to 284 g of carbohydrate and 170 to 213 g of protein. A single set of figures invites false precision; a band tells you how much of it you actually know.

What the Goal Field Does, and Does Not Do

The Goal field offers Maintain Weight and Change Weight. Both return identical numbers. Run a 30-year-old man, 175 cm and 70 kg, at the moderate multiplier on Maintain Weight and you get 2,556 calories with 256 g carbohydrate, 192 g protein, and 85 g fat. Switch to Change Weight and you get 2,556 calories with 256 g carbohydrate, 192 g protein, and 85 g fat.

So the honest instruction is: ignore that field and do the goal arithmetic yourself. Take the calorie figure the tool gives you, subtract or add what your goal calls for, then re-split the new total on 4/4/9. The section on reading your result has the ladder worked out for the reference man, and the arithmetic is three multiplications.

To size the deficit before you re-split it — a rate of loss and a date rather than a round number — run your maintenance figure through the Calorie Deficit Calculator.

We would rather tell you this than let you select a goal and trust a number that never moved. A calculator that quietly ignores a field is worse than one that never offered it.

What the Calculator Does Not Ask For

Knowing what is missing tells you which claims about your result you can safely make.

The missing body-composition field matters most for lean and heavy users at the extremes. Two people at 90 kg — one at 12 percent body fat, one at 35 percent — get identical targets from this page if their height, age, sex, and activity match, because weight is the only mass the equation sees.

• No body fat percentage — nothing here measures or accepts body composition, so the protein target is set from total weight, not lean mass.
• No diet-type choice — there is no keto, low-carbohydrate, or high-protein preset. The 40/30/30 ratio is the only one the code contains.
• No fiber, sugar, saturated fat, or sodium output — the result is three gram totals and nothing about the quality of the food inside them.
• No meal count or timing — dividing the grams across your day is left to you.
• No pregnancy, breastfeeding, or medical adjustment of any kind.

The missing food-quality output matters for everyone. Two days can hit 256 g of carbohydrate, 192 g of protein, and 85 g of fat exactly and be nutritionally very different diets. Grams are a budget, not a menu.

How to Read Your Macro Result

The readout is a starting budget, not a prescription. Three checks turn it into something you can eat: test the protein figure against your body weight, divide the grams into meals, and adjust the calorie total for your actual goal.

Check the Protein Number Against Your Body Weight

This is the first thing to do with your result, because the split sets protein from calories and your body needs it set from mass. The 2017 International Society of Sports Nutrition position stand states that "an overall daily protein intake in the range of 1.4-2.0 g protein/kg body weight/day is sufficient for most exercising individuals," rising to 2.3 to 3.1 g/kg to maximize retention of lean mass in resistance-trained people during hypocaloric periods.

If your figure lands above roughly 2.2 g per kilogram and you are not in a deliberate deficit, you are spending calories on protein that would do more work as carbohydrate around your training. Cap protein at something between 1.6 and 2.2 g per kilogram, then push the calories you freed into the carbohydrate line.

The correction is arithmetic. The reference man at 2.0 g/kg wants 140 g of protein, not 192. That releases 52 g of protein, 207 calories, which becomes another 52 g of carbohydrate and turns his split into roughly 48 / 22 / 30 — a ratio the calculator will not produce but that his body may prefer.

For a protein target derived from your body weight and training rather than from a percentage of calories, use the Protein Calculator.

Turning Grams Into Meals

The same position stand puts the per-serving guide at 0.25 g of high-quality protein per kilogram of body weight, or an absolute dose of 20 to 40 g, ideally spaced every three to four hours.

The man's three-meal pattern puts 64 g in each sitting, well past the top of that band, so four to six feedings suit his target better than three. The woman's four-meal pattern lands at 30 g, right in the middle, and needs no rearranging. A higher protein total does not just mean more food — it means more meals.

• Reference man, 192 g of protein: 64 g across 3 meals, 48 g across 4, 38 g across 5, 32 g across 6.
• A sedentary 60 kg woman at 1,584 calories, 119 g of protein: 40 g across 3 meals, 30 g across 4, 24 g across 5.
• Per-dose guide for a 70 kg body: 0.25 × 70 = 17.5 g minimum, with 20 to 40 g the practical band.

Carbohydrate and fat are far less sensitive to timing. Put the largest carbohydrate portions around the sessions that are hard, and let fat fill whatever calories remain, since it is the macro with the widest tolerance and the highest energy density at 9 calories per gram.

What the Grams Leave Out

Three gram totals say nothing about the quality of the food filling them. Overlay the public-health limits on the reference man's 2,556 calories and the gaps become concrete.

That last point is worth pausing on. A 40/30/30 split is not a low-fat plan by WHO's reckoning; it is the maximum WHO suggests, every day. If your fat sources skew toward saturated fat, the split makes it easy to breach the 10 percent saturated limit while still hitting your macros perfectly.

• Fiber: the DRI adequate intake is 38 g a day for men aged 19 to 30 and 25 g for women, derived from a basis of 14 g per 1,000 calories — about 36 g at 2,556 calories and about 22 g at a 1,584-calorie total. It is counted inside the 256 g carbohydrate line, not on top of it.
• Saturated fat: WHO advises no more than 10 percent of total energy, which is about 28 g at 2,556 calories — one third of the 85 g total fat allowance.
• Free sugars: WHO advises under 10 percent of energy, about 64 g, a quarter of the 256 g carbohydrate line.
• Total fat: WHO advises 30 percent of energy or less. This split sits at exactly 30 percent, on the ceiling rather than under it.

Hitting three gram targets is a necessary condition for a good diet, not a sufficient one. Fiber, saturated fat, free sugars, sodium, and micronutrients all live inside those same grams and none of them appear in the readout.

Adjusting the Total for Loss or Gain

Because the Goal field does not do this, here is the arithmetic. Pick a calorie change, apply it to the total, then re-split on 40/30/30 — or on whatever ratio your protein check pointed you toward.

A percentage deficit scales better than a flat one across different body sizes. Twenty percent off the reference man's maintenance total gives 2,044 calories, which on 40/30/30 is 204 g carbohydrate, 153 g protein, and 68 g fat. Applied instead to the reference woman's 1,850, the same 20 percent gives 1,480 calories — where a flat 500-calorie cut would have left her at 1,350, a 27 percent reduction.

The targets also expire as your body changes. The reference man who loses 5 kg no longer has a 2,556-calorie maintenance level: re-entering 65 kg returns 2,478 calories with 248 g carbohydrate, 186 g protein, and 83 g fat. The plan drifts by 8 g of carbohydrate and 6 g of protein for every 5 kg lost, which is small per step and compounds over a long diet.

Recalculate every four to six weeks, after a change of about 4 to 5 kg, or whenever your training load shifts. Then check the scale: two to three weeks of eating at a figure, weighed and averaged weekly, tells you more about your real maintenance level than any equation.

Limits: Where a Fixed 40/30/30 Split Stops Working

The result looks precise — four whole numbers, no ranges. Almost none of that precision is earned. Four separate limits stack up before you have eaten anything.

A Percentage Split Ignores Your Body Weight

This is the structural limit, and it explains most of the odd results people get from macro calculators generally. Protein requirement scales with body mass. A percentage of calories scales with activity. Those are different things, and this page ties protein to the second.

The consequence is visible in one line of the chart: the reference man's protein target runs from 148 g to 247 g across the six activity settings, 2.12 to 3.53 g per kilogram, without his body changing at all. At the top of that range he is being handed more protein than any published guideline supports, and the extra is displacing carbohydrate he would use during the very training that put him in that row.

Treat the protein number as the one output to overwrite. Set protein from your weight, then let carbohydrate and fat share what is left.

Where 40/30/30 Sits Against Published Ranges

The 2005 Dietary Reference Intakes define Acceptable Macronutrient Distribution Ranges for adults: carbohydrate 45 to 65 percent of energy, fat 20 to 35 percent, protein 10 to 35 percent.

Only carbohydrate falls outside, and it is a deliberate trade rather than an error: the split buys extra protein by spending carbohydrate, which is a common and defensible choice for preserving muscle in a deficit. But it is a choice, and the page should say so rather than present 40 percent as a neutral default. Moving to the 45 percent floor would give the reference man 288 g of carbohydrate instead of 256 — 32 g more, paid for by dropping his fat line from 85 g to 71 g.

None of this makes the split harmful for a healthy adult. It makes it one reasonable option among several, and the earlier table of alternatives is there so you can pick the one that matches what you actually train for.

The Calorie Total Underneath Is an Estimate Too

Every gram on this page is a percentage of a number that was itself a guess. Three separate weaknesses live in that number.

There is also a small rounding residue worth knowing about, because it looks like a bug and is not. Each macro is rounded to a whole gram independently, so multiplying the rounded grams back by 4, 4, and 9 rarely returns the calorie figure exactly. The reference man's 256, 192, and 85 g re-add to 2,557 against a stated 2,556. The widest gap across the four chart profiles is 6 calories: the 30-year-old woman at 165 cm and 60 kg on the light setting is given 1,815 calories, and her 182, 136, and 61 g re-add to 1,821.

• The activity multiplier is unverified. For the reference man, each of the four 0.175-wide steps in that dropdown is worth 289 calories and 22 g of protein, while the last step up to the athlete setting is only 0.1 wide and worth 165 calories and 12 g; the full span from sedentary to athlete is 1,319 calories and 99 g of protein.
• Only one resting-metabolism equation is available here — Mifflin-St Jeor. It is the best-validated choice: a 2005 systematic review found it predicted resting metabolic rate within 10 percent of measured values in more people, obese and non-obese, than Harris-Benedict, Owen, or WHO/FAO/UNU. The same review concluded that noteworthy errors remain when it is applied to an individual.
• Nothing range-checks the numbers you enter. A blank box is caught before the equation runs: leave Age, Height, or Weight empty and the amber panel names it — "Enter a value for Age.", or "Enter a value for: Age, Height, Weight." when more than one is blank. A typed 0 is different, because it counts as a value and goes straight through. Enter 0 for age and the reference man's total rises from 2,556 to 2,788 calories, 279 g carbohydrate instead of 256, with no warning at all.

That residue runs to a handful of calories at most across the profiles above, and it is far smaller than the uncertainty in the calorie estimate itself. Do not chase it. If your food-tracking app disagrees with the readout by five or six calories, the app is not wrong and neither is this page.

People and Situations This Page Is Not Built For

The equation underneath is an adult equation derived on a specific population, and a fixed macro ratio adds its own exclusions on top.

Thyroid disorders, fever, recent large weight loss, and many medications all shift resting metabolism in ways eight input fields cannot see. If any of those describes you, the figures here are a rough anchor and a clinician's estimate is the one to plan around.

• Under 18. Mifflin-St Jeor was derived on adults aged 19 to 78; children and adolescents need age-specific equations this page does not carry.
• Pregnancy and breastfeeding add energy and protein requirements no BMR equation includes, and a fixed split cannot represent them.
• Ketogenic and very-low-carbohydrate eating. At 40 percent of calories, carbohydrate here is 256 g for the reference man, roughly five to ten times a ketogenic allowance. This calculator cannot produce that pattern at any setting.
• Kidney disease and other conditions with a prescribed protein limit. A target of 2.7 g per kilogram is not something to adopt from a web page when a clinician has set a number.
• Competitive physique preparation, where protein is usually set per kilogram of lean mass rather than as a share of calories — the 2014 evidence review for natural bodybuilding recommends 2.3 to 3.1 g per kilogram of lean body mass, a quantity this page has no field to compute.

Used as intended — a healthy adult, honest about their week, willing to overwrite the protein line and adjust after three weeks on the scale — this page gets you a workable starting budget in about twenty seconds. That is what it is for, and claiming more for it would be dishonest.