Keto Macro Calculator
Daily fat, protein and net carb targets in grams — with every step of the maths shown, so you can check it.
How accurate is a keto calculator? It estimates average needs to within roughly 10% for most adults. Use it as a starting point and adjust after three weeks of real data.
How this calculator works
- Resting energy uses the Mifflin-St Jeor equation, which is widely used in clinical nutrition for estimating resting energy expenditure. If you enter your body fat percentage, it switches to the Katch-McArdle equation (370 + 21.6 × lean body mass), which is often more accurate when body fat is known.
- Activity multiplies resting energy by a factor based on your weekly hours of sport (1.2 for none up to 1.9 for more than ten hours).
- Goal applies a 20% deficit for weight loss or a 10% surplus for muscle gain, never going below your resting energy.
- Carbs are fixed at 20 g net for weight loss, 25 g for maintenance and 30 g for muscle gain.
- Protein is 1.6 g per kg for weight loss (using your target weight, so it does not scale with body fat), 1.4 g/kg to maintain and 1.8 g/kg for muscle gain. With body fat entered, protein is set from lean mass instead: 2.0 g per kg of lean mass for loss, 1.8 to maintain, 2.2 for muscle gain.
- Fat fills the remaining energy.
How to use the result
Treat carbs as a ceiling, protein as a target, and fat as a range — eat fat until satisfied rather than forcing the number. Recalculate after every 5 kg of change. For the reasoning behind setting grams instead of percentages, see keto macros explained.
Limits
Equations estimate averages. Your real needs can be several hundred calories different. Watch your weekly average weight for three weeks and adjust from there. Not suitable for children, pregnancy or medical diets.
Frequently asked questions
How accurate is a keto calculator?
It estimates average needs to within roughly 10% for most adults. Use it as a starting point and adjust after three weeks of real data.
Should I eat all my fat grams?
No. Fat is the flexible macro — eat enough to feel full. Under-eating fat is fine if you are not hungry.