How this macro calculator works
The calculator runs the same three steps a good coach would. First it estimates your Basal Metabolic Rate (BMR) — the calories you burn at rest — using the Mifflin-St Jeor equation, the most accurate formula for the general population. Then it multiplies your BMR by an activity factor to get your maintenance calories (TDEE), the amount you burn on a typical day. Finally it adjusts that number for your goal and splits the total into grams of protein, carbs and fat based on the diet style you pick.
None of this is magic, and no formula is perfect — these equations carry a margin of roughly 5–10% because real metabolisms vary. Treat the result as a precise starting point, not a law. The real accuracy comes from using these numbers for two weeks, watching the scale and the mirror, and nudging from there. If your weight isn't moving the way you want, adjust calories by 100–150 and reassess.
How much protein, carbs and fat you actually need
Protein is the macro to anchor first. It preserves muscle when you're losing fat, builds it when you're gaining, and keeps you fuller than carbs or fat per calorie. Most people doing body-composition work do well around 1.6–2.2g per kg of bodyweight — our protein calculator dials this in precisely.
Fat shouldn't drop too low — it supports hormones and helps you absorb vitamins. Keeping fat at or above roughly 0.6g per kg of bodyweight is a sensible floor. Carbs then fill the remaining calories. They're your main training fuel, so active people and lifters generally feel and perform better with carbs on the higher side. For the deeper logic on ratios, see finding the right macronutrient ratio.
Choosing a macro split
The diet-style toggle changes how your calories are divided:
- Balanced (30/40/30): a flexible default that suits most people and most goals. Start here if you're unsure.
- High protein (40/35/25): best for fat loss and muscle gain — more protein means better satiety and muscle retention.
- Low carb (35/25/40): steadier energy for people who feel better with fewer carbs, without going full keto.
- Keto (30/5/65): very low carb to stay in ketosis. Effective for some, restrictive for most.
There's no single 'best' split — adherence beats optimisation. The split you'll actually follow for months outperforms the theoretically perfect one you abandon in a week. If tracking macros stresses you out, read macro tracking without stress first.
Actually hitting your macros
Knowing your numbers is the easy part — logging food against them every day is where most people quit. Traditional trackers make you search a database or scan a barcode for everything, which is slow for real, restaurant and home-cooked meals. Macroo takes a plain-English description like 'chicken wrap and a flat white' and returns the calories and macros instantly, then shows how close you are to the targets this calculator gave you. It's $9.99 once, no subscription — see how it stacks up in our comparison hub.