Keto Macro Calculator

The ketogenic diet is a very low-carbohydrate, high-fat diet that shifts the body’s primary fuel source from glucose to ketone bodies, a metabolic state called ketosis. Precisely hitting the macro targets is important for staying in ketosis and achieving the intended metabolic effects.

Standard Keto Macro Ratios:

• Fat: 70–75% of total daily calories
• Protein: 20–25% of total calories
• Carbohydrates: 5–10% of total calories (typically 20–50g net carbs per day)

How this calculator actually sets your macros

Percentage splits like “70% fat, 25% protein, 5% carbs” are how keto is usually described, and they are a poor way to set a target. A percentage of calories tells you nothing about whether you are eating enough protein to keep muscle, and when you cut calories the percentage keeps your protein falling with them, which is exactly backwards. So this page works in the other direction, fixing the two numbers that matter and letting fat take up the slack:

1. Calories come from your body: Mifflin-St Jeor gives basal metabolic rate, an activity factor turns that into total daily energy expenditure, and your goal applies a deficit or surplus.
2. Carbs are whatever you type in the net-carbs box. That is a ketosis decision, not a maths one, so the calculator does not guess it.
3. Protein is anchored to lean body mass at 0.9 g per pound, with lean mass estimated from body mass index, age and sex.
4. Fat fills the remainder: Fat (g) = (Calories − Protein × 4 − Carbs × 4) ÷ 9

The percentages in the results table are an output of that, not an input to it. They will usually land near the classic 70/25/5 and they are allowed to drift, which is the point.

Calorie-to-grams conversions:

• Fat: 9 calories per gram
• Protein: 4 calories per gram
• Carbohydrates: 4 calories per gram

Net Carbs = Total Carbs − Fiber. Fiber and most sugar alcohols do not raise blood sugar, so they are subtracted. This is the number on which ketosis depends, which is why it is the one thing you enter directly.

Worked example

A 180 lb, 5 ft 10 in, 30-year-old man, sedentary, losing weight on a 20% deficit, at 20 g net carbs.

• Basal metabolic rate: 10 × 81.6 kg + 6.25 × 177.8 cm − 5 × 30 + 5 = 1,783 cal
• Total daily expenditure at 1.2: 2,139 cal, and a 20% deficit gives a target of 1,711 cal
• Body mass index 25.8, so estimated body fat is 1.2 × 25.8 + 0.23 × 30 − 16.2 = 21.7%, leaving 141 lb of lean mass
• Protein: 141 × 0.9 = 127 g (507 cal)
• Carbs: 20 g at 4 cal each, so 80 cal
• Fat: (1,711 − 507 − 80) ÷ 9 = 125 g (1,124 cal)

That works out at 66% fat, 30% protein, 5% carbs. Higher protein and lower fat than the textbook ratio, because a 180 lb man carrying 141 lb of lean mass needs the protein more than he needs the percentage to look tidy.

Ketosis reference: Most people enter ketosis within 2–4 days of restricting carbs below 20–30g net carbs per day. Blood ketone levels of 0.5–3.0 mmol/L indicate nutritional ketosis. Test with blood ketone meters (most accurate) or urine strips (convenient but less precise after adaptation).