How do I calculate my macros for weight loss?

Work out your resting energy with the Mifflin-St Jeor equation, multiply it by your activity level to get your daily burn, then eat 10 to 20% less. Set protein first from your body weight (at least 1.5 g per kg while losing weight), give fat about 30% of calories, and let carbs fill the rest. The calculator above does all of this for you.

What is a good macro split for weight loss?

For most people losing weight, about 25 to 35% of calories from protein, 35 to 45% from carbs and 25 to 35% from fat works well. We set protein in grams from your body rather than as a percentage, so it stays high enough to protect muscle even when calories drop.

Why does the calculator ask what I ate?

A target alone does not show what to change. Comparing it with a real day shows which macro is short and which is over, for example enough calories but too little protein. Foods you type in are estimated from a typical portion, so treat the comparison as approximate.

How accurate is a macro calculator?

Mifflin-St Jeor predicts resting energy within 10% of a lab measurement for about 8 in 10 people. Your weight trend over 2 to 3 weeks tells you whether calories need a nudge. Food estimates without a photo or grams are approximate; logging a day as you eat is far more exact.

How fast will I lose weight?

The timeline uses about 7,700 kcal per kilogram of body fat and lowers your daily burn as your weight falls, so loss is faster at first and slows near your goal. Real weeks go up and down with water and food volume.

Does this work if I take a GLP-1 medication?

Yes. With a GLP-1 we never cut more than 10% under your burn, because the medicine already lowers intake, and protein has a minimum of 1.6 g per kg. Follow your prescriber's advice on how fast to lose weight.

The calculator is free and asks for no email. To check a real day exactly, Protein Buddy is free to try on iPhone and Android, with manual and barcode logging free with no limit.

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Macro calculator for weight loss

Get your daily calories, protein, carbs and fat for weight loss, built around your body, lifestyle and goal. Then see how what you actually eat compares, and when you could reach your target weight.

Answer a few quick questions, tell us what you ate, and get your plan side by side with your real day.

Your calories and macros for weight loss
Your real day compared with your plan
When you could reach your target weight

Get my macros for weight loss

CALCULATE MY MACROS

Protein Buddy

The short answer

How to calculate your macros for weight loss

Find your daily burn, eat 10 to 20% less, then split those calories into protein, carbs and fat. Protein comes first, in grams from your body weight, because on fewer calories it is what protects muscle. Fat gets about 30% of calories and carbs fill the rest. For a typical woman in her 40s that lands around 1,500 to 1,700 kcal, with 100 to 120 g of protein.

The formula this calculator uses

Resting energy. Mifflin-St Jeor: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161 for women, + 5 for men.
Daily burn. Multiply resting energy by activity: 1.2, 1.375, 1.55 or 1.725.
Weight-loss calories. Eat 20% (steady) or 10% (gentle) under your burn, never under 1,200 kcal for women or 1,500 for men.
Protein first. At least 1.5 g per kg of body weight while losing weight, more if you train, 1.6 g per kg on a GLP-1.
Fat, then carbs. Fat at about 30% of calories, carbs fill what is left. Fiber: 14 g per 1,000 kcal.

Worked examples

Each row was computed with the formula above at the steady pace.
You	Calories	Protein	Carbs	Fat
Woman, 45, 5′5″, 170 lb, walks 2 to 3 times a week	1,560	110 g	163 g	52 g
Woman, 55, 5′4″, 200 lb, mostly sitting, on a GLP-1	1,610	110 g	171 g	54 g
Man, 45, 5′10″, 210 lb, trains 4 to 5 times a week	2,290	180 g	222 g	76 g

The second row is lighter on the deficit because a GLP-1 already lowers appetite, and its protein uses an adjusted weight, so the target follows muscle rather than total weight.

Made for your situation

What makes your macros personal

Every answer either changes a number or changes the advice you get with it.

Body, age and activity

They set your daily burn, the base every other number is built on.

Pace and GLP-1

A steady or gentle deficit, capped at 10% when a GLP-1 already lowers appetite.

How you like to eat

Balanced, low carb, keto or paleo change how calories split between carbs and fat.

Your target weight

Turns your plan into a timeline, slowing as you get closer, the way real weight loss does.

What you actually ate

Your day next to your plan shows which macro is short and which is over, so you know what to change first.

Why the mix matters

Calories decide the weight, macros decide what you lose

When people cut calories without strength work, around a quarter of the weight they lose is muscle. Enough protein and some resistance training shift that loss towards fat, keep you fuller, and keep your daily burn from dropping as fast.

A helpful estimate

Any equation is a starting point, and food estimates without a photo or grams are approximate. Not medical advice: if you are pregnant, under 18, or managing kidney disease, diabetes medication or an eating disorder, ask a qualified clinician for your numbers.

Check our sources

Research and guidance

Want to check our work? These sources explain the numbers we use.

Mifflin-St Jeor equationThe resting energy equation behind your daily burn.
Comparison of resting energy equationsRates Mifflin-St Jeor the most accurate for most adults.
National AcademiesSets the healthy ranges for fat, carbs and fiber.
ISSN guidance for active adultsSupports higher protein while training and losing weight.
PROT-AGE guidance for older adultsSupports more protein with age.
GLP-1 nutrition advisoryExplains protein and nutrition during GLP-1 treatment.
Muscle during weight loss reviewHow much of lost weight is muscle, with and without exercise.
Protein in weight lossWhy protein helps fullness and keeps muscle on fewer calories.
Remembered vs real intakeWhy a day from memory is only an estimate.
Food tracking and weight lossLinks regular tracking to better results.

Frequently asked questions

How do I calculate my macros for weight loss?: Work out your resting energy with the Mifflin-St Jeor equation, multiply it by your activity level to get your daily burn, then eat 10 to 20% less. Set protein first from your body weight (at least 1.5 g per kg while losing weight), give fat about 30% of calories, and let carbs fill the rest. The calculator above does all of this for you.
What is a good macro split for weight loss?: For most people losing weight, about 25 to 35% of calories from protein, 35 to 45% from carbs and 25 to 35% from fat works well. We set protein in grams from your body rather than as a percentage, so it stays high enough to protect muscle even when calories drop.
Why does the calculator ask what I ate?: A target alone does not show what to change. Comparing it with a real day shows which macro is short and which is over, for example enough calories but too little protein. Foods you type in are estimated from a typical portion, so treat the comparison as approximate.
How accurate is a macro calculator?: Mifflin-St Jeor predicts resting energy within 10% of a lab measurement for about 8 in 10 people. Your weight trend over 2 to 3 weeks tells you whether calories need a nudge. Food estimates without a photo or grams are approximate; logging a day as you eat is far more exact.
How fast will I lose weight?: The timeline uses about 7,700 kcal per kilogram of body fat and lowers your daily burn as your weight falls, so loss is faster at first and slows near your goal. Real weeks go up and down with water and food volume.
Does this work if I take a GLP-1 medication?: Yes. With a GLP-1 we never cut more than 10% under your burn, because the medicine already lowers intake, and protein has a minimum of 1.6 g per kg. Follow your prescriber's advice on how fast to lose weight.
Is it free?: The calculator is free and asks for no email. To check a real day exactly, Protein Buddy is free to try on iPhone and Android, with manual and barcode logging free with no limit.