A macro calculator answers a practical question that a calorie count alone does not: how much of what you eat should come from protein, carbohydrate and fat. This one estimates your daily calorie needs from your body and activity, adjusts them for your goal, and splits the result into grams you can track in any food log.
How to use the macro calculator
- Choose US or metric units, then enter your sex, age, height and weight.
- Pick the activity level that matches a typical week, not your best week.
- Choose a goal: lose, maintain or gain, with a deficit or surplus of 250 or 500 calories a day.
- Choose a macro split, or pick Custom and type your own protein, carbohydrate and fat percentages (they must add to 100).
- If you already have a calorie target, enter it in Daily calories to skip the estimate.
- Set meals per day to see per-meal targets, then compare other splits in the table.
How macros are calculated
First the calculator estimates resting energy with the Mifflin–St Jeor equation, multiplies it by your activity factor to get maintenance calories (TDEE), and adds or subtracts the goal adjustment. Then each macro gets its share of those calories, divided by its energy density:
Carbohydrate (g) = calories × carb % ÷ 4
Fat (g) = calories × fat % ÷ 9
The 4–4–9 values are the Atwater general factors used on US nutrition labels. The fiber target uses the Dietary Guidelines for Americans benchmark of 14 grams per 1,000 calories.
Worked example
A 30-year-old man, 5 ft 10 in and 180 lb, who exercises moderately (×1.55) and wants to lose about a pound a week, using the balanced 25/45/30 split:
BMR = 10 × 81.6 + 6.25 × 177.8 − 5 × 30 + 5 ≈ 1,783 kcal; × 1.55 ≈ 2,763 kcal maintenance; − 500 = 2,263 kcal/day.
Protein = 2,263 × 25% ÷ 4 ≈ 141 g · Carbohydrate = 2,263 × 45% ÷ 4 ≈ 255 g · Fat = 2,263 × 30% ÷ 9 ≈ 75 g.
Over three meals that is about 47 g protein, 85 g carbohydrate and 25 g fat each, plus roughly 32 g of fiber a day.
Choosing a macro split
| Split (P/C/F) | Who tends to use it |
|---|---|
| Balanced 25/45/30 | General health and gradual weight change; sits inside every AMDR |
| Higher carb 20/55/25 | Endurance athletes with long training sessions |
| High protein 40/30/30 | People cutting body fat who want more satiety |
| Lower carb 35/25/40 | People who feel better with fewer starches |
| Ketogenic 20/5/75 | A therapeutic or very-low-carb approach, best supervised |
Protein first
If you only track one macro, track protein. Sports nutrition position stands put useful intakes for active people at roughly 1.2–2.2 grams per kilogram of body weight, well above the 0.8 g/kg RDA for sedentary adults. The tape shows your protein per pound or kilogram so you can check it lands in a sensible range; the protein intake calculator goes deeper.
Carbs and fat are the flexible part
Once protein is set, carbohydrate and fat mainly trade calories with each other. Very low fat intakes (under about 20% of calories) can make it hard to absorb fat-soluble vitamins, while very low carbohydrate intakes can blunt hard training. Most people do well somewhere between those extremes.
Adjusting over time
Treat the first numbers as a starting point. Weigh yourself several times a week and compare two- to three-week averages. If weight is not moving as planned, change total calories by 100–200 a day and keep the same split. For more on the calorie side, see the calorie calculator and the weight loss timeline calculator.
Informational only — not medical advice. If you are pregnant, have diabetes or kidney disease, or have a history of disordered eating, plan your diet with a doctor or registered dietitian.
Frequently asked questions
What are macros?
Macros, short for macronutrients, are the three nutrients that supply calories: protein and carbohydrate at about 4 kcal per gram and fat at about 9 kcal per gram. Alcohol also supplies energy (about 7 kcal per gram) but is not counted as a macro here.
Which macro split is best for weight loss?
For weight loss, the calorie deficit matters far more than the split. Higher-protein splits help many people feel full and hold on to muscle while eating less, so a split with 25–40% protein is a common choice. Pick one you can follow for months.
Why does the calculator warn that my split is outside the AMDR?
The Acceptable Macronutrient Distribution Ranges from the National Academies are 10–35% of calories from protein, 45–65% from carbohydrate and 20–35% from fat. Low-carb and ketogenic splits fall outside them by design. That is not automatically unsafe, but it is a good reason to plan the diet with a dietitian.
Should I hit my macros exactly every day?
No. Being within about 5–10 grams of each target, and averaging close over a week, is plenty for most goals. Calories and protein usually matter most; carbs and fat can flex from day to day.
Can I enter my own calorie target?
Yes. Type it in the optional daily calories field and the calculator skips its own estimate. That is useful if a dietitian gave you a number or your weight trend shows the estimate is off.