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Keto calculator

Your keto macros, worked the way keto actually works: net carbs pinned to a hard cap, protein set from your body weight, and fat taking whatever calories are left. Set your own carb limit below. Nothing is sent anywhere.

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Why this runs in a different order

An ordinary macro split sets protein and fat and hands the remainder to carbohydrate. Keto cannot work that way, because the carb figure is the entire point: it is a threshold, not a leftover. So the order inverts. Carbs are capped first, protein comes off your body weight, and fat absorbs everything that is left of the calorie target.

The percentages you see are the output of that, not the input. This is also why the fat number moves so much when you change your goal: it is the only macro with any slack in it.

Net carbs, so total carbohydrate minus fibre.
Net carbs a day	Who it suits
20 g	Strict, the fastest route into ketosis and the one most plans start on
25 to 30 g	The usual working range once you are adapted
35 to 50 g	Liberal or targeted keto, workable if you train hard and stay active
Over 50 g	Low carb rather than keto. Perfectly good, just not ketosis for most people

Fat is a ceiling, not a target. The most common keto mistake is treating the fat number as a quota and eating butter to reach it. On a deficit, part of your fat comes from you. Coming in under the fat figure is normal.

Before you start

The first fortnight is usually the hard bit, and most of what people call keto flu is salt and water rather than carbohydrate withdrawal. Cutting carbs drops insulin, insulin drops sodium, and sodium takes water with it. Eating more salt than feels sensible fixes most of it.

Keto is not required for fat loss and it is not better than a normal deficit at equal calories. What it is good at is making some people much less hungry, and hunger is what breaks diets. If it suits you, that is a real advantage. If it does not, nothing is being missed.

Not doing keto? The macro calculator is the general version, and it is the better starting point for almost everybody.

Sources

How this was made

Written by Abdullah Javaid, founder of Calfit, drafted with AI assistance and edited by hand. Calories come from the Mifflin St Jeor equation and an activity factor, adjusted for your goal. Net carbs are fixed at the limit you set, protein is set at 1.6 g per kilogram of body weight, and fat takes the remaining calories at 9 kcal per gram.

Quick questions

How many carbs a day on keto?

Twenty to fifty grams of net carbs is the usual band, and 20 to 25 is where most people reliably reach ketosis. Net carbs means total carbohydrate minus fibre, because fibre is not absorbed and does not raise blood sugar. Some people hold ketosis at 50 g and some need 20; the only way to know is to test.

How much protein on keto?

Around 1.6 g per kilo of body weight, which is where this calculator sets it. The old advice to keep protein low, on the theory that excess protein turns into glucose, has not held up well: gluconeogenesis is demand driven rather than supply driven. Too little protein on a deficit costs you muscle for no benefit.

What is the right keto macro split?

Roughly 70 to 75% of calories from fat, 20 to 25% from protein and 5% from carbs, though the percentages are the consequence rather than the plan. The carbs are a fixed gram cap, the protein is set from your body weight, and fat takes whatever is left. That is why this tool works in that order.

Do I have to eat that much fat?

No. This is the most common misreading of the split. The fat figure is a ceiling that fills your calorie target, not a quota to hit. If you are in a deficit, some of the fat you burn is your own, and eating under the fat number is normal and fine.

Can you lose weight on keto without counting?

Many people do, because cutting carbs removes a lot of what they were overeating and protein and fat are filling. It still works through a calorie deficit; keto just makes the deficit happen without being tracked. When that stops working, counting is what finds out why.

How is this different from the macro calculator?

The order is inverted. The macro calculator sets protein and fat and lets carbs take the remainder. This one pins carbs to a hard gram cap first, sets protein from body weight, and gives everything left to fat. Same calories, a different plan.

Keto calculator

Why this runs in a different order

Before you start

Sources

How this was made

Quick questions

Related reading

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Protein calculator

Macro tracking for beginners