Macro Calculator for Protein, Carbs & Fat
This macro calculator works out how much protein, carbohydrates, and fat you should eat each day to reach your goal. Enter your stats, pick a goal and diet type, and your macro split appears instantly in grams and percentages. It is built for anyone who wants more control than calorie counting alone — losing fat, building muscle, or maintaining their current body composition.
Macronutrients (macros) are the three energy sources your body runs on, and each has a distinct job and calorie density:
Protein
Builds and repairs muscle tissue. 4 kcal per gram.
Carbohydrates
Primary fuel for energy and brain function. 4 kcal per gram.
Fat
Supports hormones, vitamin absorption, and long-term energy. 9 kcal per gram.
The tool uses the Mifflin-St Jeor equation — the most clinically validated formula for estimating Basal Metabolic Rate (BMR) — then adjusts it for your activity level to find your Total Daily Energy Expenditure (TDEE). Your macro targets are derived from that calorie goal and your chosen diet type.
How to Calculate Your Macros
Results update automatically as you fill in your information — there is no calculate button to press.
Choose your unit system
Select Metric (kg and cm) or Imperial (lb, feet, and inches) at the top. Switching units clears the height field to prevent incorrect conversions.
Enter your personal info
Fill in your gender, age, weight, and height. All four fields are required for the calculation to run, and results appear as soon as valid data is entered.
Select your activity level
Pick the option that fits a typical week — from Sedentary (desk job) through Lightly, Moderately, and Very Active, up to Extremely Active (physical job or twice-daily training).
Set your goal and diet type
Choose a goal — Lose Weight (−500 kcal), Lose Slowly (−250 kcal), Maintain, Gain Slowly (+250 kcal), or Gain Muscle (+500 kcal) — then a diet type (Standard, High Protein, Low Carb, or Keto) to set how those calories split across macros.
Read your results
The panel shows your BMR, TDEE, and daily calorie target, followed by exact gram and percentage targets per macro and a donut chart of the split. Use the per meal toggle to spread your macros across 3 or 5 meals.
Features
Mifflin-St Jeor BMR Formula
Estimates resting calorie needs with separate male and female formulas, then multiplies BMR by your activity multiplier (1.2 to 1.9) to find TDEE.
Five Fitness Goals
Set a calorie target relative to your TDEE: lose fast (−500 kcal), lose slowly (−250 kcal), maintain, gain slowly (+250 kcal), or gain muscle (+500 kcal).
Four Diet Types
Pick a macro split that matches your approach — Standard (30/40/30), High Protein (40/35/25), Low Carb (35/25/40), or Keto (25/5/70).
Metric and Imperial Support
Toggle between metric (kg, cm) and imperial (lb, ft + in). Height conversion is automatic and unit labels update in real time.
Macro Donut Chart
An interactive donut chart shows the calorie split across protein, carbs, and fat. Hover any segment to read its exact kilocalorie value.
Per Meal Breakdown
Switch between a 3-meal and 5-meal plan to see protein, carbs, fat, and calories divided per meal alongside your daily totals.
Auto-Calculate
Results refresh as you type or change selections — no button needed. Inputs are debounced so the math runs only after you pause.
1,200 kcal Safety Floor
If your TDEE minus your deficit drops too low, the daily target is automatically capped at a 1,200 kcal minimum.
Frequently Asked Questions
How do I calculate my macros?
Enter your gender, age, weight, and height, choose your activity level, then pick a goal and diet type. The calculator finds your daily calorie target and splits it into protein, carb, and fat grams using your chosen percentage ratio. Everything updates automatically as you go.
How do I calculate macros from my calories?
Multiply your daily calorie target by each macro's percentage, then divide by its calorie density. Protein and carbs are 4 kcal per gram and fat is 9 kcal per gram. For example, 30% of 2,000 kcal is 600 kcal of protein, which is 150 g. This tool does that math for you the moment you choose a diet type.
What is a good macro ratio for weight loss?
A higher-protein split helps preserve muscle in a calorie deficit, so High Protein (40% protein / 35% carbs / 25% fat) is a popular choice for fat loss. Standard (30/40/30) is a balanced starting point, and Low Carb suits people who prefer fewer carbohydrates. Pair any of them with the Lose Weight or Lose Slowly goal.
What macro split is best for muscle gain?
For building muscle, combine a calorie surplus (the Gain Slowly or Gain Muscle goal) with enough protein. High Protein (40/35/25) supplies plenty of protein, while Standard (30/40/30) keeps carbs higher to fuel training. Both work well — choose based on how many carbs you feel best training on.
Is 40/30/30 a good macro ratio?
A 40/30/30 split (40% carbs, 30% protein, 30% fat) is a balanced, beginner-friendly ratio close to this tool's Standard diet type of 30% protein / 40% carbs / 30% fat. It keeps protein moderate and carbs sufficient for energy, which works for general fitness and maintenance.
What are BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest to keep basic functions running. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor — the calories you actually burn in a full day. This tool calculates BMR with the Mifflin-St Jeor equation, then scales it to TDEE.
How accurate are these results?
The numbers are estimates based on statistical population averages. Individual factors such as muscle mass, metabolic variation, hormones, and health conditions are not accounted for. Use them as a starting point and adjust based on real-world progress over 2 to 4 weeks.
Why is my calorie target capped at 1,200 kcal?
Eating below 1,200 kcal a day carries health risks including nutrient deficiencies and metabolic adaptation, so the calculator never sets a daily target lower than that. If your TDEE minus your deficit falls below 1,200 kcal, consult a healthcare professional before going lower.
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