Free · No sign-up · Runs in your browser
Work out exactly how many calories, grams of protein, carbs and fat you need each day. Set a goal, pick a diet style, and get a macro split you can actually eat — plus a per-meal breakdown so you know what to put on the plate.
Fill in your details and press calculate to see your calories and macro split.
These are estimates. Track your weight over 2-3 weeks and adjust if the numbers are not moving the way you expect.
Why this one
Most macro calculators hand you three flat percentages and call it a day. That is the part they get wrong — percentages ignore how much you actually weigh.
Protein is set in grams per kilogram of body weight, then fat and carbs fill the rest. That is how coaches actually program it, and it stops a lighter person being handed 200 g of protein just because a percentage said so.
Balanced, high protein, low carb, keto and high carb each change the fat and carb ratio properly — keto drops carbohydrate to a genuine ketogenic range instead of just nudging the slider.
Daily totals are abstract. Split across three, four or five eating occasions, the numbers turn into something you can build a plate around without doing arithmetic at the fridge.
Calories will not drop below widely used minimums, fat never falls under the level needed for hormone health, and deficits are capped. Aggressive is an option; reckless is not.
Everything runs client-side in a few kilobytes of JavaScript. No libraries, no tracking pixels, no waiting on a server, and nothing you type ever leaves your device.
Full keyboard support, proper labels on every input, numeric keypads on mobile and colour contrast checked against WCAG. Macro colours are always paired with text labels, never colour alone.
How to use it
Switch to metric or imperial, then add your age, sex, height and current weight. These four values drive the equation that estimates how much energy your body burns at rest.
Be honest here — this is where most people overshoot. Count structured exercise, not a busy day. If you are between two options, choose the lower one and adjust later.
Losing fat, maintaining, or building muscle. Pace sets how far your calories move from maintenance, from a gradual ten per cent up to a faster twenty per cent.
This decides how the remaining calories split between carbohydrate and fat once protein is set. Choose the one you can actually live with — adherence beats optimisation every time.
Why macros
A calorie target alone tells you nothing about body composition. Hitting a protein floor during a deficit is the single biggest lever for losing fat rather than lean tissue, which is why protein gets set first here.
Protein and fibre drive fullness. When your split is built around them instead of whatever was left over, the same calorie budget stops feeling like a punishment by day four.
Guessing gives you nothing to change when progress stalls. A concrete starting point means you can shift calories by a hundred or two and see what happens, which is the whole point.
Carbohydrate is what powers hard sessions. Matching it to your actual training load is the difference between a session that flies and one that falls apart in the last ten minutes.
The method
Nothing here is a black box. Your basal metabolic rate comes from the Mifflin-St Jeor equation, the most accurate of the widely used predictive formulas for the general population. That gets multiplied by an activity factor to give maintenance calories, then adjusted for your goal. Protein is assigned by body weight, fat by diet style, and carbohydrate takes whatever is left.
| Diet style | Protein | Fat | Carbohydrate | Best suited to |
|---|---|---|---|---|
| Balanced | 1.8 g/kg | ~28% of calories | Remainder | Most people, most of the time |
| High protein | 2.2 g/kg | ~27% of calories | Remainder | Cutting while lifting seriously |
| Low carb | 1.9 g/kg | ~42% of calories | Remainder | Appetite control, blood sugar |
| Keto | 1.6 g/kg | ~70% of calories | Capped near 30 g | Genuine ketogenic eating |
| High carb | 1.6 g/kg | ~22% of calories | Remainder | Endurance and high training volume |
Protein and carbohydrate are counted at four calories per gram, fat at nine. Fat is never allowed below roughly 0.5 g per kilogram of body weight, since going lower for long stretches is linked to hormonal disruption. If you are in a deficit, protein is nudged upward — it is the macro that protects lean mass when energy is short.
Predictive equations carry a real margin of error, usually around ten per cent in either direction, because they cannot see your body composition, genetics or the small daily movement that varies enormously between people. Treat the output as a starting line rather than a verdict. Weigh yourself a few mornings a week, take the weekly average, and if it has not moved in the direction you want after two or three weeks, shift calories by 150 to 200 and hold again. For related reading, our guide on how much protein you actually need goes deeper on the protein figure, and the 10,000 steps myth covers why daily movement matters more than the activity multiplier suggests.
Questions
A macro calculator estimates how many calories you need each day and then divides that total into grams of protein, carbohydrate and fat. It starts by predicting the energy your body burns at rest, scales that by how active you are, adjusts for whether you want to lose fat, maintain or gain, and finally splits the result into the three macronutrients according to the diet style you choose.
Find your maintenance calories, then subtract between ten and twenty per cent. Keep protein high — around two grams per kilogram of body weight — so the weight you lose is mostly fat rather than muscle. Keep fat at a moderate level for hormone health, and let carbohydrate take the remainder. Select “Lose fat” in the calculator above and it applies all of this automatically, including a floor so calories never drop to an unsafe level.
There is no single best ratio, and the research is fairly consistent on this: once calories and protein are matched, the split between carbohydrate and fat makes very little difference to fat loss. A common starting point is roughly 35 per cent protein, 35 per cent carbohydrate and 30 per cent fat, but the ratio you will actually stick to for twelve weeks beats the one that looks optimal on paper.
For most people who train, somewhere between 1.6 and 2.2 grams per kilogram of body weight per day covers it, with the higher end being useful during a calorie deficit or when trying to add muscle. Someone entirely sedentary needs considerably less. This calculator assigns protein from your body weight and diet style rather than from a flat percentage, which is why the number changes when you switch goals.
No. Landing within about five to ten grams of each target is close enough, and what matters far more is the weekly average than any single day. Protein is the one worth prioritising because it is hardest to make up later; carbohydrate and fat can shift around each other freely as long as total calories stay roughly where you want them.
Yes, though not constantly. Recalculate after every four to five kilograms of change, or whenever progress has been flat for two to three weeks. A lighter body burns fewer calories, so the deficit that worked at the start gradually shrinks to maintenance if you never revisit it. Changing your activity level or training programme is also worth a fresh calculation.
Calories determine whether your weight goes up or down; macros determine what that change is made of and how you feel getting there. Tracking macros means you are tracking calories anyway, since the two are mathematically linked. If you only had capacity to watch one number, calories would win — but hitting a protein target alongside it is what keeps the result muscle-sparing.
It uses the Mifflin-St Jeor equation, which is generally accurate to within about ten per cent for most adults and is the formula most commonly recommended for predicting resting metabolic rate. It cannot account for body composition, medication, thyroid function or how much you fidget, so treat the result as an educated starting point and let two to three weeks of real-world data fine-tune it.
Your macro targets are the easy part — two minutes and a scroll up. What moves the needle is what you do with them over the next month. Start with the split you can genuinely stick to, weigh in a few times a week, and adjust once you have real data rather than a first impression.
Calculate my macrosThis tool provides general nutrition estimates for healthy adults and is not medical advice. If you are pregnant, managing a health condition, taking medication that affects appetite or metabolism, or have a history of disordered eating, speak to a doctor or registered dietitian before changing your intake.