---
title: "Free Macro Calculator — Calories & Macros for Any Goal | Boost Fitness"
canonical_url: "https://boostfitness.io/tools/macro-calculator"
last_updated: "2026-09-02T05:56:16.775Z"
meta:
description: "Free macro calculator: get your BMR (Mifflin-St Jeor), TDEE, and a daily protein, fat and carb split in grams for fat loss, maintenance or muscle gain."
"og:description": "Free macro calculator: get your BMR (Mifflin-St Jeor), TDEE, and a daily protein, fat and carb split in grams for fat loss, maintenance or muscle gain."
"og:title": "Free Macro Calculator — Calories & Macros for Any Goal | Boost Fitness"
---
Boost Fitness
# Free macro calculator
**Work out your BMR with the Mifflin-St Jeor equation, your TDEE from your activity level, and a daily protein, fat, and carbohydrate target in grams for fat loss, maintenance, or muscle gain. This macro calorie calculator is free and needs no sign-up.**
**Sex**
**Age (years)**
**Height**
**Weight**
**Activity level**
**Goal**
BMR (Mifflin-St Jeor)
**1770 kcal **
TDEE (maintenance)
**2740 kcal **
Daily calorie target
**2740 kcal **
Protein (30%)
**205 g **
Fat (30%)
**90 g **
Carbs (40%)
**275 g **
**General guidance, not medical advice**
This calculator gives population-level estimates for healthy adults. It is not a diagnosis or a prescription — speak to your GP or a registered professional before making significant changes, especially if you are pregnant, under 18, or managing a medical condition.
## How this macro calculator works
The calculation runs in three steps. First, your **basal metabolic rate (BMR)** — the energy your body uses at complete rest — is estimated with the **Mifflin-St Jeor equation** (10 × weight in kg + 6.25 × height in cm − 5 × age, plus 5 for men or minus 161 for women). It is the predictive equation most consistently found to be accurate for the general population, which is why dietitians favour it over the older Harris-Benedict formula.
Second, BMR is multiplied by an activity factor (1.2 for sedentary up to 1.9 for extra active) to estimate your **total daily energy expenditure (TDEE)** — what you actually burn across a normal day, training included. Third, your goal adjusts the target: a 20% deficit for fat loss, TDEE itself for maintenance, or a 10% surplus for muscle gain.
## From calories to macros
Calories are then divided between the three macronutrients using per-goal presets — for fat loss, 40% protein / 30% fat / 30% carbs; for maintenance, 30 / 30 / 40; for muscle gain, 30 / 25 / 45 — and converted to grams at 4 kcal per gram of protein and carbohydrate and 9 kcal per gram of fat. Protein stays high in every preset because it protects muscle and manages hunger; carbohydrate rises when the goal is gaining, because it fuels the training volume that drives growth. Grams are rounded to the nearest 5 — precision beyond that is noise once real-world food tracking is involved. If you want to sense-check the protein figure specifically, our [protein intake calculator](https://boostfitness.io/tools/protein-intake-calculator) shows the evidence-based range per kilogram of body weight.
## Limitations — and when a coach should adjust
Every number on this page is an estimate built from population averages. Mifflin-St Jeor is typically within about 10% of measured values, but that still means a 200+ kcal error for many people, and activity multipliers are honest guesses at best — most people overestimate their activity level by one category. Very muscular and very lean people tend to be underestimated; the equation also knows nothing about medical conditions, medications, or a history of aggressive dieting.
The fix is not a better formula — it is feedback. Track your intake and body weight for two to three weeks: if the scale trend does not match the goal (roughly 0.5–1% of body weight lost per week in a cut, 0.25–0.5% gained per month in a lean bulk), adjust calories by 10–15% and reassess. This is exactly the loop coaches run with [Boost Fitness nutrition coaching](https://boostfitness.io/features/nutrition) : targets are prescribed to each client's calendar, the client logs food in the built-in diary, and the coach adjusts from real data instead of formulas.
**Useful detail **
## Frequently asked questions
Macronutrients are the three nutrient groups your body needs in large amounts: protein and carbohydrate (about 4 kcal per gram each) and fat (about 9 kcal per gram). "Counting macros" means hitting daily gram targets for each rather than just a calorie total — which gives you control over muscle retention, satiety, and training fuel, not just weight change.
It is the most accurate of the common predictive equations for the general population, typically landing within about 10% of measured resting energy expenditure. But it is still an estimate built from averages — your true expenditure depends on muscle mass, hormones, and daily movement. Treat the output as a starting point and adjust from two to three weeks of real weigh-in data.
For most people, yes — consistency beats complexity, and a fixed daily target is far easier to stick to. Some coaches use higher-carb training days and lower-carb rest days, which can help very active clients, but it only matters once the basics (total calories and protein) are consistently in place.
In a calorie deficit, higher protein (here 40% of calories) protects lean muscle, keeps you fuller between meals, and has the highest thermic effect of the three macros — meaning more of its calories are burned during digestion. It is the single most protective macro when losing weight.
The 20% deficit is deliberately moderate, but for lighter or smaller-framed people it can still produce a low number. As a rule of thumb, be cautious below roughly 1,400–1,500 kcal per day without professional supervision — a smaller deficit sustained for longer is safer and usually more successful than an aggressive one that collapses after three weeks.
**Keep calculating **
## More free tools
[**One Rep Max Calculator**
Estimate your 1RM from any set with the Epley and Brzycki formulas, plus a 50–95% loading table.](https://boostfitness.io/tools/one-rep-max-calculator) [**BMI Calculator**
Body mass index in metric or imperial units, with NHS categories and honest limitations.](https://boostfitness.io/tools/bmi-calculator) [**Protein Intake Calculator**
An evidence-based daily protein range (1.2–2.2 g/kg) for your body weight and goal.](https://boostfitness.io/tools/protein-intake-calculator)
From Boost Fitness — see [**nutrition coaching features **](https://boostfitness.io/features/nutrition), [**pricing **](https://boostfitness.io/pricing), or [**how we compare **](https://boostfitness.io/compare).
**Ready when you are**
## Prescribe targets to clients automatically
**Boost Fitness turns numbers like these into daily calorie, macro, and training targets on each client's calendar — with a food diary, programme builder, and progress tracking built in. Start your 30-day free trial.**
[Start your 30-day free trial](https://boostfitness.io/register) [Explore nutrition coaching](https://boostfitness.io/features/nutrition)
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