ReckonBoxHow this calculator works
Macros are the three nutrients that carry calories: protein, carbohydrate, and fat. A macro plan is just your daily calorie target split into grams of each. This tool finds your total daily energy expenditure from your size and activity, adjusts it for your goal, then divides those calories into the split you choose.
The math behind the grams is simple. Protein and carbs give 4 calories per gram, fat gives 9. So 2,000 calories on a balanced 40/30/30 split becomes 200 g of carbs, 150 g of protein, and 67 g of fat.
Take a 30 year old man, 180 cm and 75 kg, training four days a week. His maintenance is about 2,682 calories. On the balanced preset that lands at 201 g protein, 268 g carbs, and 89 g fat. Switch to keto and the same calories become 209 g fat, 168 g protein, and just 34 g carbs.
The diet presets
Each preset is a carbs, protein, and fat split of your calories. There is no single correct ratio, so pick the one that fits how you like to eat.
| Preset | Carbs | Protein | Fat |
|---|---|---|---|
| Balanced | 40% | 30% | 30% |
| Low carb | 20% | 40% | 40% |
| High protein | 40% | 40% | 20% |
| Keto | 5% | 25% | 70% |
Protein, carbs, and fat
Protein is the macro to anchor first, because it protects muscle and keeps you full. The International Society of Sports Nutrition recommends 1.4 to 2.0 grams per kilogram of bodyweight to build and hold muscle, rising to 2.3 to 3.1 grams per kilogram when you are cutting hard. Carbs fuel training and hard days, so lifters and runners do better with more of them. Fat supports hormones, and dropping it too low for too long backfires. The presets above hit sensible defaults, but protein is the one worth setting deliberately.
Adjusting for your goal
Calories decide your weight, so the goal you pick shifts the calorie target before the split. Maintain holds at your TDEE. Lose drops it by about 500 calories a day, roughly half a kilo or a pound a week. Gain adds about 500 for a lean-leaning bulk. Across every goal, keeping protein high is what lets you lose fat without losing muscle, or gain muscle without much fat.
How to hit your macros
A target is only useful if you can eat to it. Weigh food for the first week or two until you learn what 30 grams of protein or 40 grams of carbs looks like, then you can eyeball most meals. Track in any free app, build a handful of go-to meals that already fit, and aim to land within about 5 grams of each target rather than chasing perfection. Protein is the number to hit most closely; carbs and fat can trade off around it.
Frequently asked questions
What are macros? Macros are the three nutrients that carry calories: protein, carbohydrate, and fat. Protein and carbs give 4 calories a gram, fat gives 9. Hitting a calorie target while keeping protein high is the core of most diets.
How much protein should I eat? The ISSN recommends 1.4 to 2.0 grams of protein per kilogram of bodyweight to build and hold muscle, and up to 2.3 to 3.1 grams when you are cutting. That is roughly 0.6 to 1 gram per pound.
Do the macro percentages matter for weight loss? Calories decide weight; macros decide how you feel and what you keep. For fat loss, keep protein high, then split the rest of the calories between carbs and fat to taste.
This tool is an estimate, not medical or dietary advice. For a plan built around your health, talk to a doctor or a registered dietitian.