How to calculate macros, then turn them into meals

The four steps in one table

The method is the same on every calculator, and it is only arithmetic. Here it is with the choices we used for the example later on, all of them estimates.

Steps 2 to 4 give you grams you can weigh on a kitchen scale. Step 1 is where most of the uncertainty sits, so it gets the most space.

Step 1: estimate your calories

Start with resting energy, the calories your body uses doing nothing. The equation most often used is Mifflin-St Jeor, derived from 498 healthy adults whose resting energy was measured by indirect calorimetry (Mifflin and colleagues, 1990). In its simplified form it is 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then + 5 for men or − 161 for women. A dietetics systematic review found it more likely than the other equations tested to land within 10% of the measured value, while warning of "noteworthy errors" for individuals (Frankenfield, Roth-Yousey and Compher, 2005).

For a 30-year-old woman who is 165 cm tall and weighs 65 kg (5 ft 5 in, 143 lb), that is 650 + 1,031 − 150 − 161 = 1,370 calories a day at rest, an estimate.

Then multiply by an activity level. The FAO, WHO and United Nations University expert consultation on human energy requirements groups lifestyles by "physical activity level": 1.40 to 1.69 for sedentary or light activity, 1.70 to 1.99 for active or moderately active, and 2.00 to 2.40 for vigorous (FAO/WHO/UNU, 2004 report). It adds that about an hour a day of moderate to vigorous exercise can raise a person from about 1.55 to about 1.75.

The table shows what that range does to one person. Nothing about her changed except the multiplier.

The choice of multiplier moves her estimated target by 822 calories, more than a third of her middle value. That is far more than the 5% by which Mifflin and colleagues found the older Harris-Benedict equation overestimated measured resting energy, so spend your doubt on the multiplier. If you are unsure, start from the middle of the range that fits and look at how you feel and how your weight trend behaves over a few weeks, rather than trusting either number to the calorie. We used 1.55 and rounded her estimate of 2,124 to 2,100 calories.

Steps 2 to 4: from calories to grams

Protein first, because it is the one with the stronger evidence for a target in grams per kilogram. A meta-analysis of 49 trials and 1,863 healthy adults found that, in people doing resistance training, protein supplementation stopped producing extra fat-free mass beyond a total intake of about 1.62 g per kg a day (Morton and colleagues, 2018). So 1.6 g per kg is a reference point for an example, not a limit and not a recommendation: ask a professional what suits you.

Then check where that lands as a share of calories. The National Academies' acceptable macronutrient distribution ranges for adults are 10% to 35% of calories from protein, 20% to 35% from fat and 45% to 65% from carbohydrate (National Academies, citing IOM 2002/2005). The ranges were set to combine adequate nutrient intake with lower chronic disease risk, so most plans can sit well inside them. Fat at 30% is a common middle choice, and carbs take whatever is left.

We worked the method for two adults, both at the 1.55 multiplier, with the target rounded to the nearest 50 calories. Calories from each macro use the standard factors of 4 per gram of protein, 4 per gram of carbohydrate and 9 per gram of fat, all estimates.

Both land inside the National Academies ranges, with protein near the middle of its range and carbs in the lower half of theirs.

Why a percentage split can mislead

Many calculators skip the grams-per-kilogram step and ask you to pick a split, such as 40% carbs, 30% protein and 30% fat. The split looks neutral, but it hides how much protein you are actually setting. Applied to the same 2,100 estimated calories, 30% protein is 158 g, which is 2.4 g per kg for our 65 kg woman. For the man at 2,700 calories it is 203 g, or 2.5 g per kg. Both are about 50% above the 1.62 g per kg point at which Morton and colleagues saw no further gain in fat-free mass in healthy adults doing resistance training (estimated).

That does not make a high-protein split wrong for everyone. It means you should know what it asks of you before you copy it, and the quickest way to know is to divide the protein grams by your weight in kilograms. We saw the same trap elsewhere: in two of the four ChatGPT meal plans we recounted, the printed macros were the calorie target times the announced percentages, not a sum of the foods, and the recounted carbs in all four came in 23 to 59 g a day below the printed ones (estimated). Our ChatGPT meal plan check has the table.

Turn the numbers into one real day

Here is the step most pages skip. We composed a day for the woman, aiming at 104 g of protein, 70 g of fat and 264 g of carbs, from foods you can find in a US supermarket, and added up every line with USDA FoodData Central values. Weights are as noted: oats dry; chicken, salmon, rice, broccoli and potato cooked. It is one example, not a recommendation to eat it.

Against the targets, the day is 18 calories under (about 1%), 3 g of protein over (3%), 10 g of carbs over (4%) and 2 g of fat under (3%), all estimated. Fiber, which is part of the carbs, is 37.6 g.

Two of the choices carry most of the calories: the 18 g of olive oil, which supplies 159 calories, and the almonds and peanut butter, 240 calories between them. Fat targets are easy to overshoot because oil and nuts are small in volume and large in calories, so a tablespoon of oil you do not weigh adds about 120 calories (estimated), nearly half of what the whole baked potato supplies. The protein is spread over five eating occasions, between about 10 and 34 g each, which is just how the foods fell, not a rule.

Weigh cooked and dry foods the way the table says. According to USDA, 100 g of brown rice is 123 calories cooked, and oats are 389 calories per 100 g dry. Entering a cooked weight against a dry value, or the reverse, can move one meal by hundreds of calories (estimated). Our macro-friendly meal prep guide uses the same USDA method on five recipes you can cook in one afternoon.

Keep the numbers honest

One last check, on the arithmetic itself. Adding up the day's macros with the standard factors (4 calories per gram of protein, 9 per fat and 4 per carbohydrate) gives 2,140 calories, while USDA's own energy values for the same foods sum to 2,082, a gap of 58 calories, about 3% (estimated). The gap is expected: the FAO describes the Atwater general factors as a single value per nutrient regardless of the food, with carbohydrate measured by difference so that it includes fiber (FAO, Food energy: methods of analysis and conversion factors). Our day has 37.6 g of fiber, and the FAO's proposed extensive factor system gives fiber 2 calories per gram, not 4 (it notes this has not yet been implemented). So a macro tally and a calorie tally will not match exactly, and you do not need them to.

Then treat the targets as a hypothesis. The systematic review above found Mifflin-St Jeor within 10% of measured resting energy for more people than the other equations, not for everyone. On 2,100 calories a 10% error is about 1,900 to 2,300 estimated, and the activity multiplier adds its own spread. Follow the numbers consistently for two or three weeks and watch your weight trend, your hunger and your energy. If they do not fit, change the calories and keep the method. Do not chase a daily total: macros are a weekly pattern, and a day that is 5% off is a normal day. The review's own advice on estimated equations is to use judgment:

The Expert Panel advises clinical judgment regarding when to accept estimated RMR using predictive equations in any given individual.

When to ask a professional instead

This is general information, not medical advice. If you have diabetes, kidney disease or a food allergy, are pregnant or breastfeeding, are under 18, have or have had an eating disorder, or take medication that affects your appetite or blood sugar, ask a doctor or a registered dietitian for your numbers before you follow any macro targets. If a professional has already given you calorie or macro targets, use theirs, not the ones from a formula. Counting grams can be a hard habit to keep healthy for some people, so stop and talk to someone if it starts to cause worry about food.

Doing this every week without the spreadsheet

This part is written by the team behind MacroRecipe, so read it with that in mind. The method above is easy to do once and tedious to repeat: a day of food needs 17 lines, and a week of different days is 100 or more. If you enjoy the arithmetic, a spreadsheet and a kitchen scale are enough, and USDA FoodData Central is the place to look up values.

MacroRecipe does the matching step instead. It plans your week of menus around your macros and the goal you choose, from dishes you pick, with ingredient data from USDA and CIQUAL (ANSES). It sizes portions toward your estimated calorie and protein targets. Swap a dish and the portions and the grocery list follow, with quantities added up across recipes.

Who it isn't for: MacroRecipe runs on iPhone only, not on Android. It has no barcode scanner, no food database to search and no complete daily food diary, though a photo scan of a meal eaten elsewhere comes with the subscription. You can preview your first menu for free, after which it is a paid subscription. If you would rather log what you eat, see our MacroFactor alternatives guide.

How we calculated

Every food line is the portion in grams multiplied by its value per 100 g in USDA FoodData Central, SR Legacy, from the April 2018 CSV downloaded from the USDA dataset page on 2026-10-20. Calories are USDA's own energy values, not recomputed. Carbohydrate is by difference, as USDA lists it. We used the first matching food for each item and did not mix brands.

• Equation. Mifflin-St Jeor in its simplified form, as printed in the 1990 paper, with the activity levels of the FAO/WHO/UNU report and the multiplier 1.55 for both adults.
• Protein. 1.6 g per kg, from the plateau point of Morton and colleagues (1.62 g per kg), rounded down. It is a plateau point for adults doing resistance training who add protein, not a minimum for everyone and not a limit.
• Rounding. Targets are rounded to the nearest 50 calories and to whole grams; table rows are rounded, so the lines can differ from the total by a tenth.
• Not tested. We did not measure anyone's energy use, and the day was not weighed in a kitchen. It is a recount of a composed menu, not a trial.

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