Getting your macros roughly right is most of what makes keto work. Too little protein and you lose muscle; too little fat and you are hungry and miserable; too much carbohydrate and you never reach ketosis. This calculator gives you a sensible starting point in seconds. Enter your details, pick a goal, and it works out your daily calories and the grams of protein, fat and net carbs to aim for.
Estimates use the Mifflin-St Jeor equation, net carbs fixed at 20g for ketosis, and protein set to protect muscle (1.8g/kg on a deficit, 1.6g/kg at maintenance). A starting point, not a prescription. How these macros work →
How the numbers are worked out
The calculator uses the Mifflin-St Jeor equation, the most accurate of the common formulas, to estimate the calories you burn at rest, then scales that by your activity level to get your daily total. From there it adjusts for your goal: a moderate deficit for fat loss, level for maintenance, a small surplus for gain.
The macros then follow keto logic rather than the usual high-carb split:
- Net carbs are fixed at 20g. Low enough to get almost everyone into ketosis reliably, and the one number you should not drift above while you are adapting.
- Protein is set to protect muscle, a little higher on a deficit so you hold onto lean mass while losing fat, slightly lower at maintenance. It is not “low” the way old keto advice claimed; that myth costs people muscle.
- Fat fills the rest. On keto, fat is the lever you adjust for energy, not the thing you fear. Eat more on a maintenance or gain target, slightly less in a deficit, and let it carry the calories carbohydrate used to.
How to actually use these
Treat the figures as a target to eat towards, not a daily exam to pass. Hit your protein most days, keep net carbs under the line, and use fat to dial energy up or down depending on hunger and how the scale and tape measure move over a few weeks. If fat loss stalls for three weeks or more, that is the point to tighten things rather than on day three. The macros explainer goes deeper on each number, and if you are just starting out, the first 30 days guide covers the rest.
These are estimates from population averages, not medical advice. If you are pregnant, on medication, or managing a condition such as diabetes, speak to a doctor or dietitian before changing how you eat.