Macro Split Calculator
Take a daily calorie target and split it into grams of protein, carbs and fat. Pick a goal preset or set a custom ratio with three sliders that always add up to 100. Optional per-meal breakdown for whatever number of meals you actually eat.
Explain like I'm 5 (what even is this calculator?)
Calories tell you how much energy is on the plate. Macros (short for macronutrients) tell you where that energy comes from: protein, carbs or fat. This page takes one number (your daily calories) and splits it three ways using a percentage rule, then converts each share into grams using the standard calorie-per-gram values for each macro.
Split your calories
Need a daily calorie number first? Use the TDEE Calculator to work out your Total Daily Energy Expenditure, then drop that number in here.
Daily macros
- Protein0 g (0 kcal)
- Carbs0 g (0 kcal)
- Fat0 g (0 kcal)
Per meal (4 meals/day)
- Calories0 kcal
- Protein0 g
- Carbs0 g
- Fat0 g
Prove it
The split runs in two steps for each macro.
Step 1. Multiply the daily calories by the macro percentage to get calories for that macro.
Step 2. Divide those calories by the kcal-per-gram for that macro: 4 for protein, 4 for carbs, 9 for fat (the Atwater factors).
Worked example, 2000 kcal on the balanced preset (30 / 40 / 30):
- Protein: 2000 × 0.30 = 600 kcal ÷ 4 = 150 g
- Carbs: 2000 × 0.40 = 800 kcal ÷ 4 = 200 g
- Fat: 2000 × 0.30 = 600 kcal ÷ 9 = 67 g (66.67 rounded)
Per-meal numbers are the daily figures divided by your meals/day, rounded to the nearest gram.
Useful? Save this calculator: press Ctrl + D to bookmark it.
What a macro split is for
Macros are the three sources of food energy your body actually runs on: protein, carbohydrate and fat. Calories are the unit those sources are measured in, but two diets at the same calorie total can feel completely different in practice. A 2000 kcal day at 40 percent carbs leaves you with the energy to run a half marathon. The same 2000 kcal at 5 percent carbs leaves you in nutritional ketosis. The split is what changes, not the total.
The point of fixing a target macro split is to make the daily food question simpler. Once you know you are aiming for, say, 150 g of protein, the question on each plate becomes "where is my protein on this plate?" rather than "is this meal healthy?" Useful for muscle gain, recomp, endurance training, and anyone whose nutritionist has handed them a target ratio.
Common mistakes
The first one is treating the percentages as if they were grams. They are not. 30 percent protein on a 2000 kcal day is 600 kcal of protein, which is 150 g. On a 2500 kcal day the same percentage gives you 188 g. The grams move with calories, the percentages do not.
The second is forgetting that fat is more than twice as energy-dense per gram as protein and carbs. 70 g of fat looks small on a plate but carries 630 kcal. 70 g of carbs is 280 kcal. People underestimate fat intake on a regular basis because the volume is misleading. The kcal-per-gram column on the result table is there to keep that visible.
The third is chasing very high protein ratios that nobody actually needs. Above about 1.6 to 2.2 g per kg of body weight per day, the extra protein is mostly oxidised for energy, the same as carbs and fat. The high-protein cut preset here lands at 40 percent because cutting calories without protein loss is the one situation where a higher ratio earns its place.
Edge cases
Custom ratios are validated to within one percentage point of 100, which absorbs rounding from the sliders without letting you build an impossible split. If a slider lands you at 99 percent, the result is still calculated. If it lands you at 90 percent, the calculator refuses, because 10 percent of the day's calories would simply be missing. The sliders auto-redistribute the other two values pro-rata when you drag one, so you should rarely end up outside the tolerance unless you are typing values in directly.
Calories of zero return zeros across the board, useful for sanity-checking that the maths is not adding ghost grams from somewhere. Calories above 10,000 are rejected because nothing in normal human nutrition lands that high, and accepting them tends to mean a typo somewhere upstream.
How this fits with the other health calculators
This calculator only does the split. It does not work out the total calories. For that, use the TDEE Calculator (which gives a daily calorie figure based on your size, age and activity), or the Calorie Calculator (which adds a goal adjustment for losing, maintaining or gaining weight). Take the number those calculators give you, drop it into the calorie field above, pick a preset and you have a target macro shape for the day.
Related calculators
The macro split is the second step. These three feed it.
Frequently asked questions
How do I work out my daily calorie target before splitting it?
Use the TDEE Calculator on this site. It works out your Total Daily Energy Expenditure from age, weight, height and activity level, and adjusts for whether you want to lose, maintain or gain. The number it gives you is the one to drop into the Macro Split Calculator.
Why is fat 9 kcal per gram while protein and carbs are 4?
Those are the Atwater factors, the calorie-per-gram values used in nutrition labelling for over a century. Fat packs more energy per gram because of its chemical structure (long hydrocarbon chains release more energy when oxidised). It is the reason a tablespoon of olive oil and a slice of bread can land at roughly the same calorie count, despite looking very different on the plate.
Do my custom percentages have to add up to exactly 100?
Within one percentage point, yes. The calculator allows ±1 to absorb rounding, but anything further from 100 is rejected because it would distort the calorie split. The custom sliders auto-redistribute the other two values when you move one, so getting to a valid combination is quick.
Is keto really 70 percent fat?
Strict ketogenic diets sit around 70 to 75 percent of calories from fat, 20 to 25 percent from protein and 5 to 10 percent from carbohydrate. The preset here uses 70 / 25 / 5, which is the commonly cited starting point. Therapeutic keto diets used for epilepsy go higher still, but those are run by a clinician rather than a web page.
How accurate is the per-meal breakdown?
It is a flat divide, daily totals split by the number of meals you eat. Real-world meals vary, you might want more protein around training and more carbs at breakfast, but the per-meal numbers give you a sensible target shape so each plate looks roughly right.