Free macros to calories calculator
Grams of protein, carbs and fat — into calories.
Every other macro calculator on this site runs the arithmetic forwards: a calorie target in, grams out. This one runs it backwards. Enter the grams you already have — off a label, out of your diary, from a recipe — and it gives you the calorie total and the percentage split that total breaks into.
General wellness guidance, not medical advice. If you are pregnant, breastfeeding, under 18, or managing a medical condition, talk to a doctor or a registered dietitian before acting on any of these numbers.
4, 4 and 9 — and why they are only approximately true
Protein and carbohydrate each supply about 4 kcal per gram; fat supplies about 9. Those three numbers are the Atwater factors, and effectively every nutrition label in the world is built on them. Multiply, add, and you have the calorie content of anything you can describe in grams.
They are averages, though, not constants. Atwater derived them from whole food groups more than a century ago, and the true energy yield varies with what the food is and how it is prepared — whole almonds give up measurably less energy than the same almonds ground into butter, because some of the fat leaves the body still locked inside cell walls. A few per cent of disagreement between this total and a packet is normal, and neither figure is lying to you.
The one macro worth setting in grams
Percentage splits are how diets are described and a poor way to plan one. The problem is that a percentage moves when your calories move: set protein to thirty per cent and it quietly falls every time you cut, which is exactly when you need it to hold. Protein is a property of your body, so it belongs in grams — that is what the protein calculator is for. Carbs and fat can then divide whatever is left, largely by preference and by what you will actually stick to.
Which makes this page the sanity check rather than the plan: you have the grams already, and you want to know what they add up to and roughly how they are distributed.
Where the total usually goes missing
Three things account for nearly every unexplained gap. Fibre, which is included in total carbohydrate on a US label and excluded on most others, and which yields about 2 kcal per gram rather than 4. Sugar alcohols, common in "no added sugar" products, which sit between 0 and 3. And alcohol, at roughly 7 kcal per gram — not a macro, not on this page, and very often the answer when a day's calories do not reconcile.
Common questions
How do you convert grams of protein, carbs and fat into calories?
Multiply protein by 4, carbohydrate by 4 and fat by 9, then add them up. Those are the Atwater factors — the same numbers every nutrition label is built on. So 30 g protein, 40 g carbs and 10 g fat is 120 + 160 + 90 = 370 kcal.
Why does my total differ from the number printed on the packet?
The 4/4/9 factors are rounded averages across whole food groups, not exact constants for a particular food, and manufacturers are allowed to compute the label total in more than one way. A few per cent of disagreement is normal and does not mean either figure is wrong. Larger gaps usually come from fibre or from sugar alcohols being counted differently.
Does fibre count towards the carbohydrate calories?
It depends on the label you are reading. Outside the US, carbohydrate is usually listed excluding fibre, so entering that number here is already close to right. In the US, total carbohydrate includes fibre, which supplies roughly 2 kcal per gram rather than 4 — so a very high-fibre food will read slightly high in this calculator.
What is a good macro percentage split?
There is no single right answer, and the percentages matter less than most people think. Protein is the one worth setting in grams rather than per cent — it should hold still while calories move — and the remaining calories can be divided between carbs and fat largely by preference and by what you will actually stick to. A split is a description of a diet, not a prescription for one.
Does alcohol have calories this calculator does not count?
Yes. Alcohol supplies about 7 kcal per gram and is not one of the three macros, so a drink's calories will not appear here. If you are reconciling this total against a day that included alcohol, that is usually where the missing calories are.
Other free calculators
Knowing the number is easy. Hitting it daily is not.
NutriLog AI tracks protein as a first-class target, with a food database that knows paneer and dal as well as it knows chicken. Free, no ads, Android. Free on Google Play.