Macro Calculator
WEBSplit your daily calories into protein, carbs and fat grams for your goal.
These macros are a general starting point, not medical or nutrition advice. Talk to a professional before changing your diet.
What is the Macro Calculator tool?
This macro calculator turns a daily calorie target into grams of protein, carbs and fat. Enter your calories, choose a diet split — balanced, high-protein, low-carb or keto — and it instantly shows how many grams of each macronutrient to aim for, along with the percentage of your calories and the calories each macro provides. It is the quickest way to move from a single calorie number to a plan you can actually eat by.
The maths uses the standard Atwater energy factors that nutrition labels are built on: protein and carbohydrate each supply 4 calories per gram, and fat supplies 9 calories per gram. So a balanced 2,000-calorie day splits into roughly 150 g protein, 200 g carbs and 67 g fat. Switching presets keeps the same calories but re-weights the split — keto pushes fat up and carbs right down, while high-protein favours muscle-preserving protein. A live proportion bar shows the mix at a glance.
Everything runs entirely in your browser — your calorie target never leaves your device, nothing is uploaded, and no account is needed. It is free, works on your phone, and pairs naturally with a TDEE calculator to find the calorie number in the first place. One honest note: these presets are a sensible starting point, not a prescription. Protein needs in particular vary with body weight and training, so treat the result as a baseline and adjust with a coach or dietitian for your goals.
How to use the Macro Calculator
- Enter your daily calorie target in the calories field.
- Choose a diet split: balanced, high protein, low carb or keto.
- Read the grams of protein, carbs and fat, plus the percentage and calories for each.
- Check the proportion bar to see the mix at a glance.
- Switch presets any time to compare splits for the same calories.
Frequently asked questions
How are macros calculated from calories?
Each preset assigns a percentage of your calories to protein, carbs and fat. That energy is then converted to grams using the Atwater factors — protein and carbs at 4 calories per gram, fat at 9 — so a 30% protein slice of a 2,000-calorie day is 600 calories, which is 150 grams of protein.
What is a good macro split?
A balanced 30/40/30 (protein/carbs/fat) works for most people. High-protein (40/30/30) helps preserve muscle when losing weight, low-carb (40/20/40) suits some fat-loss plans, and keto (25/5/70) drives very low carbs and high fat. The best split depends on your goal, activity and preferences.
How much protein should I eat?
Protein needs scale with body weight and training, commonly around 1.6 to 2.2 grams per kilogram for active people, which often lands near the 30 to 40% share these presets use. Use the result as a baseline and adjust to your own targets.
What calorie target should I use?
Use your maintenance calories to hold weight, fewer to lose and more to gain. If you do not know your number, work it out first with a TDEE calculator, then bring that figure here to split into macros.
Is my data private?
Yes. Your calorie target is processed entirely in your browser — it is never uploaded, stored or sent to any server. Once the page has loaded, the calculator even works offline.
Is this macro calculator free?
Yes — free, with no sign-up, no account and no limits. Enter your calories and get your macros in seconds.