Macro Calculator: Your Daily Protein, Carbs, and Fat in Grams
A macro calculator turns a daily calorie target into grams of protein, carbs, and fat you can actually eat, weigh, and track. Instead of copying a meal plan built for someone else, you enter your body, your activity, and your goal, and you get three numbers that fit your day. Calories tell you how much to eat. Macros tell you what that food should be made of.
That split matters. Two people can both eat 2,500 calories a day and get very different results if one eats most of them as protein and the other as fat or sugar. Protein helps you hold muscle while losing weight, carbs fuel training, and fat keeps meals satisfying. You don't need exact grams daily. You do need a plan.
How this macro calculator works
The calculation runs in three steps: calories burned at rest, calories burned once movement and training are added, and how those calories split for your goal. A wrong answer at step one makes step three wrong, even if the percentages look sensible.
Step one uses the Mifflin-St Jeor equation. For a man, it is 10 times weight in kilograms, plus 6.25 times height in centimetres, minus 5 times age in years, plus 5. For a woman, it ends with minus 161. The result is your BMR, roughly what you would burn lying still all day.
Step two multiplies BMR by an activity factor: 1.2 sedentary, 1.375 light training 1 to 3 days a week, 1.55 moderate training 3 to 5 days a week, 1.725 active training 6 to 7 days a week, and 1.9 for a hard physical job plus training. The result is your TDEE, your best estimate of the calories that hold your weight steady. Step three applies your goal factor, Lose 0.8, Maintain 1, or Gain 1.15, then splits the total, since protein and carbs give 4 calories per gram and fat gives 9.
Every input, explained
Sex. Picks the equation constant, plus 5 for men, minus 161 for women. At the same size, it gives women a lower resting figure. Units. Pick kg and cm, or lb and in. The tool converts before it calculates.
Age. Whole years, from 10 to 100. Resting burn falls about 5 calories a day per extra year. Weight. Your current weight, not a goal weight or an old weight you liked better.
Height. Standing height without shoes. Taller bodies have more tissue to maintain, so at the same weight a taller person burns more at rest. Activity level. Be honest here, because this is where most targets go wrong. A desk job plus three gym sessions is moderate, not active.
Goal. Lose cuts TDEE by 20%, Maintain keeps it, Gain adds 15%. Don't pick Gain while also hoping to lose fat. Diet style. Balanced is 30/40/30. High-protein is 40/30/30. Low-carb is 40/20/40. Keto is 20/5/75. Custom shares must total exactly 100%.
A worked example: a 30 year old man, 80 kg, 180 cm, moderately active
Take a man aged 30, weighing 80 kg, standing 180 cm tall, training 3 to 5 days a week, maintaining his weight on a Balanced split. His BMR is 800 plus 1,125 minus 150 plus 5, which is 1,780 calories a day at rest. His TDEE is 1,780 times 1.55, which is 2,759 calories a day, and his Maintain target is still 2,759.
Now split that 2,759. Protein takes 30%, which is 827.7 calories, divided by 4, which is 206.9 g, rounded to 207 g. Carbs take 40%, which is 1,103.6 calories, divided by 4, which is 275.9 g, rounded to 276 g. Fat takes 30%, which is 827.7 calories, divided by 9, which is 92.0 g, rounded to 92 g. His target is 207 g of protein, 276 g of carbs, and 92 g of fat. Checking backwards gives 2,760 calories, one above target from rounding.
The same man on Lose and Gain shows how much the goal factor moves the plate. Lose multiplies 2,759 by 0.8 to give 2,207 calories, splitting into 166 g of protein, 221 g of carbs, and 74 g of fat. Gain multiplies 2,759 by 1.15 to give 3,173 calories, splitting into 238 g of protein, 317 g of carbs, and 106 g of fat. Protein moves with the total, so Gain asks for 72 g more protein than Lose, though the percentage never changes.
| Goal | Daily target | Protein | Carbs | Fat |
|---|---|---|---|---|
| Lose (0.8) | 2,207 kcal | 166 g | 221 g | 74 g |
| Maintain (1) | 2,759 kcal | 207 g | 276 g | 92 g |
| Gain (1.15) | 3,173 kcal | 238 g | 317 g | 106 g |
Change the diet style and the same 2,759 calories split very differently. Balanced gives 207 g, 276 g, and 92 g. High-protein gives 276 g, 207 g, and 92 g. Low-carb gives 276 g, 138 g, and 123 g, since 40% of 2,759 divided by 9 is 122.6 g, rounded to 123 g. Keto gives 138 g, 34 g, and 230 g. One large banana, about 27 g of carbs, would eat most of a keto day's allowance.
| Diet style at 2,759 kcal | Protein | Carbs | Fat |
|---|---|---|---|
| Balanced 30/40/30 | 207 g | 276 g | 92 g |
| High-protein 40/30/30 | 276 g | 207 g | 92 g |
| Low-carb 40/20/40 | 276 g | 138 g | 123 g |
| Keto 20/5/75 | 138 g | 34 g | 230 g |
Common mistakes
- Picking athlete activity for a desk job. Three gym sessions don't cancel out 10 seated hours, and overstating activity can turn a Lose target into a Maintain target.
- Mixing raw and cooked weights. Raw chicken and cooked chicken weigh very differently, since water leaves during cooking, while rice and pasta soak water up.
- Forgetting drinks, oils, and bites. Cooking oil, milky coffee, juice, and nuts while cooking can add 300 calories and 30 g of fat to a day that looked perfect.
- Chasing exact grams every day. A target of 207 g of protein does not fail at 195 g. Aim within about 10 g on protein, and judge the week, not a single day.
- Changing everything after one flat week. Weight swings by a kilo or more from water, salt, and glycogen. Give a target 2 to 3 honest weeks before cutting further.
Practical tips
Start with protein, since it's the hardest macro to hit by accident. Build each meal around a protein source you can name and weigh, then add carbs and fat around it. Keep a scale on the counter, prep one protein in bulk twice a week, and pre-log the meal you know you'll eat. Learn three restaurant meals that roughly match your split and rotate them, because a repeatable plan beats a perfect plan you abandon. When your trend moves the wrong way for two full weeks, adjust by about 100 calories a day, not 500.
Frequently asked questions
What macros should a 30 year old man eating 2,759 calories a day aim for?
On Balanced, 2,759 calories gives 207 g of protein, 276 g of carbs, and 92 g of fat. On High-protein it gives 276 g, 207 g, and 92 g, and on Keto it gives 138 g, 34 g, and 230 g. Run your own numbers rather than copying this example.
Why does this macro calculator ask for my sex, age, and height?
Because the Mifflin-St Jeor equation needs all three to estimate resting burn. Weight alone cannot separate a tall 80 kg man from a short 80 kg woman, and a guessed BMR gives you a guessed macro target.
Should I choose Lose, Maintain, or Gain if I want to lose fat but keep muscle?
Choose Lose, and keep protein high, since a modest deficit plus enough protein is how most people lose fat while holding muscle. A Maintain target won't move the scale, so if fat loss is the goal, the deficit does the work.
Is keto the best macro split for fast weight loss?
Not by itself. Keto can suppress hunger, and it can drop several kilos of water weight in the first week. Over months, fat loss tracks the calorie deficit far more than the split, so a short keto plan loses to a Balanced plan you keep.
How often should I recalculate my macros?
Recalculate when your weight changes by about 5 kg, your training load changes a lot, or your goal changes. Between those points, adjust by about 100 calories a day, and re-run the calculation every couple of months.
Related calculators: other new calculators in this batch include the Period Calculator for cycle dates, the Length Converter for cm, inches, feet, and miles, and the Dice Roller for games and classroom chance.
Macros stop being a mystery once you see them as a kitchen task: weigh the protein, fill the rest of the plate to match your goal, and let two or three weeks of honest tracking tell you whether the numbers fit. If the scale stalls, change one thing at a time and keep protein steady. The CalcMega Blog carries more training guides when you want another worked example.
Disclaimer: this guide explains macro math for general education only and is not medical or diet advice for any one person. Needs vary with health conditions, medicines, and pregnancy, so talk to a doctor or a registered dietitian before a strict deficit or a keto plan, and seek care if a diet makes you feel unwell.
Further reading: the CDC explains balanced eating, portion sizes, and healthy weight habits in plain language on its nutrition pages, which are a good reality check beside any macro target.