Macro calculator
The macro calculator splits a daily calorie target into grams of protein, carbohydrate, and fat. Pick a preset (balanced, high-protein, low-carb, keto, Mediterranean) or set custom percentages, and the page converts the calorie split into grams using the standard 4-4-9 conversion (4 kcal per gram of protein and carbs, 9 kcal per gram of fat). Output also includes a per-meal breakdown if you tell it how many meals you eat per day.
Formula
protein_calories = total_calories × protein_pct / 100
carb_calories = total_calories × carb_pct / 100
fat_calories = total_calories × fat_pct / 100
protein_grams = protein_calories / 4
carb_grams = carb_calories / 4
fat_grams = fat_calories / 9
The 4-4-9 calorie-per-gram conversion is from Atwater's general factors, the convention every nutrition label and dietitian uses. Alcohol is 7 kcal/g but is rarely tracked as a macro and is not modelled here.
Diet presets
| Preset | Protein | Carbs | Fat | Use |
|---|---|---|---|---|
| Balanced | 30% | 40% | 30% | General maintenance, no specific protocol |
| High-protein | 40% | 30% | 30% | Resistance training, body recomposition, satiety |
| Mediterranean | 25% | 45% | 30% | Heart-health-aligned; emphasises olive oil, fish, whole grains |
| Low-carb | 30% | 25% | 45% | Carbohydrate-sensitive, type-2-diabetes adjunct (with clinician) |
| Keto | 25% | 5% | 70% | Therapeutic ketosis (epilepsy management, some metabolic conditions) |
| Custom | Your choice | Your choice | Your choice | Any 3 percentages that sum to 100 |
Presets are reference splits from common diet protocols. None is universally "best" — different splits work for different people, training contexts, and clinical situations.
Inputs
| Field | Notes |
|---|---|
| Daily calorie target | From the calorie calculator, the TDEE calculator, or your own number |
| Diet preset | One of the 6 presets above |
| Custom percentages | Required if "Custom" preset is selected; must sum to 100 |
| Meals per day | Optional; if provided, the page divides each macro by meal count |
Output
The page returns:
- Total calories (the input echoed back).
- Protein — grams + calories + percentage.
- Carbs — grams + calories + percentage.
- Fat — grams + calories + percentage.
- Per-meal breakdown if meals/day was provided.
- A stacked-bar visualisation of the split.
Worked example
A 2050 kcal/day target (from the calorie calculator's "lose 0.5 kg/week" example) on a high-protein preset (40/30/30) split across 4 meals:
Protein: 2050 × 0.40 = 820 kcal / 4 kcal/g = 205 g/day → 51 g/meal
Carbs: 2050 × 0.30 = 615 kcal / 4 kcal/g = 154 g/day → 38 g/meal
Fat: 2050 × 0.30 = 615 kcal / 9 kcal/g = 68 g/day → 17 g/meal
205 g protein / 154 g carbs / 68 g fat per day, roughly 51 / 38 / 17 g per meal.
How to pick a preset
A few rules of thumb (general — not clinical advice):
| Situation | Often-recommended starting preset |
|---|---|
| Body recomposition / resistance training | High-protein (40/30/30) |
| Endurance training (running, cycling) | Mediterranean or balanced |
| Sedentary maintenance | Balanced |
| Type-2 diabetes adjunct (with clinician) | Low-carb |
| Therapeutic ketosis (clinician-directed) | Keto |
| Heart-health-aligned | Mediterranean |
For most people the preset doesn't matter as much as total calories + adequate protein + decent food quality. The macro split is a fine-tuning lever, not the primary one.
Limits
- Per-gram values are approximate. Atwater's general factors are an average; specific foods deviate (e.g. fibre carbs yield less than 4 kcal/g effective energy).
- Total intake matters more than precise split. Studies (e.g. Hall & Guo, Gastroenterology, 2017) repeatedly show that, at matched protein and calorie intake, the carb/fat ratio has small effects on weight outcomes for most people.
- Therapeutic protocols like keto for epilepsy or low-carb for diabetes are clinical questions — work with a dietitian or physician, not a free calculator.
- Per-meal split is even split — the calculator divides evenly. Real-world meal sizes vary (e.g. larger dinner, smaller breakfast); use the daily total and divide as you actually eat.
When percentage splits don't fit your situation
Some experts (e.g. coaches, registered dietitians working with athletes) prefer absolute-gram targets rather than percentages:
- Protein: set in g/kg of body weight (see protein calculator).
- Fat: floor at 0.8 g/kg of body weight for hormone health.
- Carbs: fill the remaining calorie budget.
The macro calculator doesn't model this approach directly — for that workflow, use the protein calculator to fix protein, manually pick a fat target, and infer carbs from remaining calories.
Frequently asked
Does the order of meals matter? For most people, no. Studies on meal timing for weight loss show roughly equivalent outcomes whether protein is front-loaded, back-loaded, or evenly distributed. Athletes peri-workout may benefit from timing protein near training, but daily total is the bigger lever.
Is keto safe? Keto is safe for most healthy adults short-term and is a long-established therapy for paediatric epilepsy. Adverse effects (keto flu, constipation, electrolyte imbalance) and contraindications (type 1 diabetes, certain metabolic disorders) make it a clinician-supervised choice for some people. The calculator does not give medical advice.
Why is fat 9 kcal/g but protein and carbs only 4? Atwater empirically measured the heat of combustion of each macronutrient minus what's not absorbed. Fat is more energy-dense by mass; protein and carbs are similar. Alcohol is 7 kcal/g.
Can I save my macro plan? The calculator is stateless — close the page, the result is gone. Take a screenshot, or use the meal-planner (see Nutrition and diet) to plan around the macros.
My fitness app gives different macro grams. Different apps use slightly different presets and rounding. Discrepancies of 5–10 g per macro are normal between calculators.
Where to read next
- Calorie calculator — generate the calorie target this calculator splits.
- Protein calculator — protein-specific target in g/kg.
- Nutrition and diet — log meals against your macros.
- TDEE calculator — maintenance starting point.
Last updated: 2026-05-11 Author: Ahsan Mahmood
:::note Health information — not medical advice LifeWell and this documentation are provided for general wellness and educational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment, and nothing here is intended to diagnose, treat, cure, or prevent any condition. Always consult a qualified healthcare professional with questions about your health, and never disregard or delay professional advice because of something you read here. In an emergency, contact your local emergency services. :::