How to use it
- Get a calorie target: Calculate my calories uses your sex, age, height, weight, activity and goal (the same equations as our Calorie Calculator), or choose I know my calorie target and type it.
- Pick a preset or set protein yourself, either in grams per kilogram of body weight or as a share of calories, and set fat as a share of calories. Carbohydrate gets the calories that are left.
- Read the grams a day, the grams per meal, and whether each macronutrient sits inside the recommended range for adults.
How the numbers are worked out
Protein and carbohydrate provide 4 calories per gram and fat 9. Take a woman who needs 2,246 kcal a day and weighs 150 lb (68.0 kg), with protein at 1.6 g/kg and fat at 30%: protein is 1.6 × 68.0 = 109 g (435 kcal), fat is 30% of 2,246 = 674 kcal or 75 g, and carbohydrate gets the remaining 1,137 kcal, which is 284 g. Because the grams are rounded to whole numbers they add up to 2,247 kcal, one more than the target; the calculator says so rather than nudging a number.
The ranges, and where they come from
| Macronutrient | Acceptable range for adults (share of calories) | Also useful |
|---|---|---|
| Carbohydrate | 45–65% | RDA of 130 g a day, the brain’s average glucose use |
| Protein | 10–35% | RDA 0.8 g per kg of body weight; 1.4–2.0 g/kg for most people who exercise (ISSN) |
| Fat | 20–35% |
The Acceptable Macronutrient Distribution Ranges are the official US and Canadian ranges set in the Dietary Reference Intakes: intakes inside them meet nutrient needs while keeping the risk of chronic disease low. The protein RDA of 0.8 g/kg covers the needs of nearly all healthy adults who are not especially active. For people who exercise, the International Society of Sports Nutrition’s 2017 position stand concludes that 1.4 to 2.0 g/kg a day is enough for most, a range that still falls inside the 10–35% band at typical calorie intakes. The calculator flags any macronutrient outside its range in amber; that can be a deliberate choice, but it is worth a conversation with a registered dietitian.
What we tested
On October 15, 2026 we ran the page’s own functions on 5,000 random plans (800 to 4,500 kcal, protein by weight or by share, 10 to 45% fat) against exact fraction arithmetic: grams, calories, shares and range flags matched in all 4,861 computable plans, and the 139 where protein and fat alone exceeded the calories gave a message instead. For 2,000 random adults the calorie engine returned exactly what the Calorie Calculator’s own functions return, goals and limits included. In Chromium: the default (a 35-year-old woman, 5 ft 5 in, 150 lb, low active, 1.6 g/kg protein, 30% fat) showed 2,246 kcal split as 109 g protein, 284 g carbohydrate and 75 g fat; the Balanced preset gave 112 g protein (20%); a typed 2,000 kcal target gave 100, 250 and 67 g; 45% fat was flagged with carbohydrate as outside the recommended ranges; protein and fat above the calories were refused; a target below 1,200 kcal was refused; inputs survived a reload; the page fitted a 390 px phone with no errors. We also checked the check: counting fat at 4 instead of 9 calories per gram made every plan fail.
Sources
Checked on .
- Health Canada: Dietary reference intakes tables, reference values for macronutrients (AMDRs, protein and carbohydrate RDAs)
- Health Canada: Dietary reference intakes tables, equations to estimate energy requirement (2023 DRI)
- Jäger R et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr 14:20
- Jensen MD et al. (2014). 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation 129(25 Suppl 2):S102-38
Frequently Asked Questions
Built by Derek Giordano · Part of Ultimate Design Tools