Macro Calculator

A 30-year-old woman who is 5 ft 6 in tall, weighs 150 lb and is lightly active needs about 1,949 calories a day to maintain her weight: 122 g protein, 65 g fat and 219 g carbs on a balanced split. Enter your own details for your estimate.

Formulas and sources checked November 5, 2026. An estimate for healthy adults, not medical advice.

Macro Calculator

Daily calories and grams of protein, fat and carbs. An estimate for healthy adults.

Units:

Sex (the equation differs):

Age (years):

Weight (lb):

Height (ft):

and inches:

Activity level:

Goal:

Macro split (% protein / fat / carbs):

Estimated daily target

1,949 calories

BMR 1,417 · maintenance 1,949 · maintain

Macro	Grams	Calories	Share
Protein	122 g	487	25%
Fat	65 g	585	30%
Carbs	219 g	877	45%

Protein works out to 1.8 g per kg of body weight.

An estimate, not medical advice. Equations like this one are within about 10% for most healthy adults and miss for some. If you are pregnant, breastfeeding, under 18, or managing a health condition, ask a doctor or registered dietitian before changing how you eat.

How the Macro Calculator Works

Four steps, each one a published formula or range:

1. Resting calories (BMR), Mifflin-St Jeor

Men: 10 × kg + 6.25 × cm − 5 × age + 5

Women: 10 × kg + 6.25 × cm − 5 × age − 161

In US units, pounds × 0.4536 gives kilograms and inches × 2.54 gives centimeters.

2. Maintenance calories

Maintenance = BMR × activity factor

Activity level	Factor	Typical week
Sedentary	×1.2	Desk job, little or no exercise
Lightly active	×1.375	Light exercise 1-3 days a week
Moderately active	×1.55	Moderate exercise 3-5 days a week
Very active	×1.725	Hard exercise 6-7 days a week
Extra active	×1.9	Physical job plus hard training

3. Goal

Losing takes 10% or 20% off maintenance; gaining adds 10%. A weight-loss target never drops below your BMR or 1,200 calories (women) / 1,500 calories (men), and never rises above maintenance. Larger deficits are not offered.

4. Grams of each macro

Grams = calories × share ÷ calories per gram

Protein and carbs have 4 calories per gram and fat 9, the general factors US food labels use. Example: 2,000 calories at 30% fat is 600 calories, or 600 ÷ 9 = 67 g of fat.

Recommended Macro Ranges for Adults

The National Academies' Acceptable Macronutrient Distribution Ranges, which the calculator checks your split against:

Macro	Share of calories	Calories per gram
Protein	10-35%	4
Fat	20-35%	9
Carbohydrate	45-65%	4

Protein can also be set by body weight: 0.8 g per kg is the adult RDA, and the 2025-2030 Dietary Guidelines suggest 1.2-1.6 g per kg may benefit many adults.

Turning Macros Into Meals

Weigh, Don’t Scoop

Nutrition labels list grams. A kitchen scale makes tracking far more accurate than cups: a scooped cup of oats or flour can weigh 20% more than the label assumes. Our grams to cups converter helps when a recipe only gives cups.

Check Your Estimate After Two Weeks

Weigh yourself under the same conditions a few times a week. If the trend doesn't match your goal after two to three weeks, adjust calories by 100-200 a day rather than starting over.

Spread Protein Across Meals

Dividing your protein over three or four meals is easier to reach than one large serving. Scale recipes to the portion you need with the recipe scaler.

Sources

Checked November 5, 2026. The activity factors are the conventional multipliers used with resting-energy equations. This calculator is for healthy adults and is not medical or dietary advice; ask a doctor or registered dietitian about your own needs.

Questions

How do I calculate my macros?

Estimate your resting calories (BMR) with the Mifflin-St Jeor equation, multiply by an activity factor to get maintenance calories, adjust for your goal, then split the calories between protein, fat and carbs. Divide protein and carb calories by 4 and fat calories by 9 to get grams.

What is the Mifflin-St Jeor equation?

A formula published in 1990 that estimates resting energy expenditure from weight, height, age and sex: 10 × weight in kg + 6.25 × height in cm − 5 × age, plus 5 for men or minus 161 for women. A 2005 systematic review found it the most accurate of the common equations, within 10% of measured values for most healthy adults.

What macro split should I use?

For most adults, a split inside the ranges set by the National Academies works: 10-35% of calories from protein, 20-35% from fat and 45-65% from carbohydrate. The balanced 25/30/45 preset sits inside all three. Higher-protein and lower-carb splits are popular for training and appetite, but the calculator flags any share outside those ranges.

How much protein do I need a day?

The RDA for healthy adults is 0.8 g of protein per kg of body weight. The Dietary Guidelines for Americans 2025-2030 say many adults may benefit from 1.2-1.6 g per kg. The calculator shows your protein in grams per kg so you can compare.

Why won’t the calculator go lower on calories?

Very low intakes are hard to sustain and can fall short on nutrients. The deficit is never more than 20% of maintenance, and the target never drops below your estimated BMR or 1,200 calories a day for women and 1,500 for men, the lower ends of the weight-loss ranges in the 2013 AHA/ACC/TOS guideline. Go lower only with a doctor’s supervision.

Is this calculator accurate for me?

It is an estimate for healthy adults aged 18 to 80. Equations based on weight and height can miss by 10% or more, especially for very muscular people, older adults and people with obesity. Track your weight for two to three weeks and adjust by 100-200 calories if it moves differently from what you expect. It is not medical advice.

Macro Calculator