Your macros take three steps to find: protein from your weight, then carbs and fat from the calories that are left, then fiber from your calories. This guide shows each step with your own numbers.
What are macros?
Macros, or macronutrients, are the three nutrients that give food its calories: protein, fat, and carbohydrates (carbs).
How many calories are in a gram of protein, carbs, and fat?
A gram of protein or carbs has about 4 kcal. A gram of fat has about 9, and a gram of alcohol about 71.
| Macro | kcal a gram | Your grams | Your kcal |
|---|---|---|---|
| Protein | 4 | 134 | 536 |
| Fat | 9 | 87 | 783 |
| Carbs | 4 | 240 | 960 |
Together they make your target of about 2,284 kcal a day. Fiber is a kind of carb, so it is part of your carbs, not a fourth macro.
How to calculate your macros by hand
Protein comes first, from your weight. Then carbs and fat split the calories that are left. Fiber comes last, from your calories. This is the order the Fit Shapes app uses.
Step 1: Find your protein from your weight
Multiply your weight in kilograms by your protein level in grams per kilogram. To change pounds to kilograms, multiply by 0.4536.
83.9 × 1.6 = 134 g of protein a day.
Step 2: Split the rest between carbs and fat
Take protein’s calories off your target: 4 kcal for each gram. Your diet gives a share of what is left to carbs. Fat takes the rest.
2,284 − 134 × 4 = 1,748 kcal for carbs and fat. A balanced diet gives 55% of it to carbs: 961 kcal ÷ 4 = 240 g. Fat takes the other 787 kcal ÷ 9 = 87 g.
Step 3: Find your fiber from your calories
Aim for 14 g of fiber for every 1,000 kcal you eat4. Fit Shapes never sets fiber above half your carbs.
2,284 ÷ 1,000 × 14 = 32 g of fiber a day.
How much protein do you need?
Most people who exercise need 1.4 to 2 g of protein for each kilogram they weigh, every day3. That is about 0.6 to 0.9 g a pound. For healthy adults in general, the recommended amount is 0.8 g per kilogram4.
The Fit Shapes app has four protein levels:
| Level | What it means | g/kg | g/lb | Your protein |
|---|---|---|---|---|
| Low | The active-adult minimum | 1.2 | 0.5 | 101 g |
| Moderate | Where added protein stops buying gains | 1.6 | 0.7 | 134 g |
| High | Top of the sports-nutrition range | 2.0 | 0.9 | 168 g |
| Extra High | Physique-prep intake | 2.4 | 1.1 | 201 g |
Protein never goes over 45% of your calories, so a small target does not turn into mostly protein. At 2,284 kcal, that limit is 257 g.
How much protein to build muscle
In a 2018 review of studies of adults who did strength training, extra protein stopped adding lean mass at about 1.6 g per kilogram a day. The authors suggest up to 2.2 g for people who want the most muscle they can gain2. So Moderate is enough for most people who want to build muscle.
How much protein to lose weight
Enough to keep your muscle while you eat less. Fit Shapes starts you at Moderate. If you lose weight while you train, High or Extra High may help you keep your muscle3. In this example, that is 168 to 201 g a day.
How many carbs should you eat a day?
It depends on your diet. Fit Shapes gives carbs a share of the calories that are left after protein: 55% on a balanced diet, 75% on low-fat, 30% on low-carb, and 8% on keto. With your protein, that gives:
| Diet | What it means | Carbs | Fat |
|---|---|---|---|
| Balanced | An even split of carbs and fat | 240 g | 87 g |
| Low-fat | More carbs, less fat | 323 g | 51 g |
| Low-carb | Fewer carbs, more fat | 130 g | 136 g |
| Keto | Very low carb, high fat | 30 g | 181 g |
For most adults, a healthy diet gets 45% to 65% of its calories from carbs4. In this example, carbs are 42% of your calories, because protein takes its share first.
Keto and low-carb limits
A common definition of a ketogenic diet is 20 to 50 g of carbs a day, and of a low-carb diet, less than 130 g5. So Fit Shapes stops carbs at 30 g on keto and at 130 g on low-carb, at any calorie target. The calories above that limit go to fat.
Net carbs vs total carbs
Fit Shapes counts total carbs, as a US food label does. Total carbs include fiber7. Net carbs are total carbs with the fiber taken away. The FDA’s label rules do not define net carbs. If you count net carbs, take your fiber off your carbs: 240 − 32 = about 208 g.
How many grams of fat per day?
At least 20% of your calories: 51 g a day at 2,284 kcal. For most adults, a healthy diet gets 20% to 35% of its calories from fat4.
Fit Shapes gives fat the calories that protein and carbs leave, and never less than 20%. In this example, fat is 87 g, or 34% of your calories.
How many grams of fiber per day?
About 14 g for every 1,000 kcal you eat4: 32 g a day at your target.
On keto, that can be more than your carbs allow. Fiber is a carb, so Fit Shapes keeps fiber at half your carbs or less. In this example, on keto, fiber is 15 g.
What is the best macro ratio for weight loss?
The one you can keep up. Your calories decide how much weight you lose. Your split decides which foods you eat to get there.
In a 12-month study of 609 adults, people on a healthy low-fat diet lost 5.3 kg (about 12 lb) on average, and people on a healthy low-carb diet lost 6.0 kg (about 13 lb). The difference was not significant6. Keep your protein up, then choose the split that suits the foods you like.
40/30/30 and IIFYM
A 40/30/30 split gives 40% of your calories to carbs, 30% to protein, and 30% to fat. Fit Shapes does not set protein as a percentage. It sets protein from your weight, so a larger person gets more protein at the same calories.
IIFYM means “if it fits your macros”. Any food can be part of your day, if the day’s grams add up.
Macros for cutting, bulking, and recomposition
The same three steps work for each goal. What changes is your calorie target and your protein level.
Cutting
To cut, you eat less than you burn, so you lose fat. Keep your protein up: High or Extra High may help you keep your muscle while you eat less3. Carbs and fat get smaller as your target gets smaller.
Bulking
To bulk, you eat a little more than you burn, so you gain weight while you train. Fit Shapes suggests a gain of 0.25 to 0.75 lb (0.1 to 0.35 kg) a week. Moderate protein is enough for most people2. The extra calories go to carbs and fat, as your diet splits them.
Body recomposition
Recomposition means losing fat and gaining muscle at the same time, with little change on the scale. To aim for it, choose to keep your weight in the sentence at the top, and keep your protein up. Your target is then about what you burn.
Macros for women and men
The math is the same. Your sex changes your calorie target: at the same size and age, the formula gives a woman a lower resting burn. Your weight sets your protein. To see a woman’s numbers, choose female in the sentence at the top.
Where your calorie target comes from
Your macros split your calorie target. The target is what you burn in a day, plus or minus the pace you choose. In this example, you burn 2,783 kcal a day. To lose 1 lb a week, you eat 2,284 kcal a day: 499 under what you burn. To see how that is worked out, use the TDEE calculator. It starts from the answers you gave here.
How to count your macros
Log what you eat, with the amount of each food, and add up its protein, fat, and carbs for the day. Then compare the totals with your targets.
- Read the label. A nutrition label gives the grams for one serving. Multiply them by the servings you eat.
- Weigh what has no label. A kitchen scale in grams is more exact than cups and spoons. Weigh food the same way each time, raw or cooked.
- Log everything. Cooking oil, sauces, and drinks have calories and macros too.
- Count total carbs. The label’s total carbs include fiber, as your target does.
An app does the adding for you. In Fit Shapes, take a photo of a meal or a nutrition label, and it goes to your log with its protein, fat, and carbs. You can also scan a barcode. Today shows what you ate against your targets. See Unified Capture.
When to recalculate your macros
Your protein moves with your weight. Your carbs and fat move with your calorie target. So recalculate when your weight changes by about 10 lb (5 kg), or when your target changes.
Fit Shapes does this each week. It measures what you burn from your log and your weight, suggests a new target every Monday, and moves your macros with it.
Questions
Do I have to hit my macros exactly?
No. Get close on most days. A few grams over or under on one day makes little difference.
Are these total carbs or net carbs?
Total carbs. Fiber is part of your carbs, as it is on a US food label. To count net carbs, take the fiber away from the total.
Does this calculator save what I type?
Only in this browser tab, and only until you close it. The math runs in your browser, and nothing you type leaves it. The tab keeps your answers so that the TDEE calculator and the macro calculator can both use them.
Can I use this calculator if I am pregnant or breastfeeding?
No. Pregnancy and breastfeeding change how much energy and protein you need, and this calculator does not count that. Ask your doctor or a registered dietitian.
Can I use this calculator if I have kidney disease or diabetes?
Ask your doctor or a registered dietitian first. These conditions can change how much protein or carbs you should eat.
Can a teenager use this calculator?
No. It is for adults 18 and older. For a younger person, ask a doctor or a registered dietitian.
Sources
- FAO. Food energy – methods of analysis and conversion factors. Report of a technical workshop. FAO Food and Nutrition Paper 77. Rome: FAO; 2003. Section 3.5.1. www.fao.org/4/y5022e/y5022e04.htm
- Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376–384. doi.org/10.1136/bjsports-2017-097608
- Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. doi.org/10.1186/s12970-017-0177-8
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press; 2005. doi.org/10.17226/10490
- Feinman RD, Pogozelski WK, Astrup A, Bernstein RK, Fine EJ, Westman EC, et al. Dietary carbohydrate restriction as the first approach in diabetes management: critical review and evidence base. Nutrition. 2015;31(1):1–13. Table 1. doi.org/10.1016/j.nut.2014.06.011
- Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JPA, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion: the DIETFITS randomized clinical trial. JAMA. 2018;319(7):667–679. doi.org/10.1001/jama.2018.0245
- U.S. Food and Drug Administration. Food labeling: nutrition labeling of food. 21 CFR 101.9(c)(6). www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9