Keto Macro Calculator

Calculate your optimal ketogenic diet macros for fat loss, maintenance, or muscle gain

Weight (kg)

Body Fat Percentage (%)

Estimate if unsure: Men 15-25%, Women 25-35%

Activity Level

Goal

Protein Intake Preference

What is the Ketogenic Diet?

The ketogenic diet is a very low-carb, high-fat diet that shares many similarities with the Atkins and low-carb diets. It involves drastically reducing carbohydrate intake and replacing it with fat. This reduction in carbs puts your body into a metabolic state called ketosis.

Ketosis

When your body doesn't have enough glucose for energy, it burns fat instead, producing ketones. This state can lead to rapid fat burning and mental clarity.

Macro Ratios

Standard keto macros are roughly 70-75% fat, 20-25% protein, and 5-10% carbs (20-50g net carbs).

Keto Food Guidelines

Eat Freely

✓Meats (beef, pork, lamb, poultry)
✓Fatty fish (salmon, sardines, mackerel)
✓Eggs (pastured or omega-3)
✓Butter and cream
✓Cheese (unprocessed)
✓Nuts and seeds
✓Healthy oils (olive, coconut, avocado)
✓Low-carb vegetables
✓Avocados

Avoid or Limit

✗Sugary foods (soda, juice, candy)
✗Grains and starches
✗Fruit (most are too high in carbs)
✗Beans and legumes
✗Root vegetables (potatoes, carrots)
✗Low-fat or diet products
✗Unhealthy oils (soybean, corn, sunflower)
✗Alcohol (most carbs, limits ketosis)
✗Sugar-free diet foods

How long does it take to reach ketosis?

Most people enter ketosis within 2-7 days of starting the keto diet, depending on your metabolism and how strictly you limit carbs. You can test for ketosis using urine strips, a breath meter, or blood meter (most accurate). Testing helps ensure you are in the optimal fat-burning state.

What is the "keto flu" and how do I avoid it?

The keto flu refers to temporary symptoms when transitioning to keto: headache, fatigue, nausea, and irritability. It is caused by your body adapting to using fat for fuel and losing water weight. To minimize symptoms, stay hydrated, replenish electrolytes (sodium, potassium, magnesium), and gradually reduce carbs instead of going cold turkey.

Can I build muscle on a ketogenic diet?

Yes, you can build muscle on keto, though it may require more attention to protein intake. Consume 0.8-1.0g of protein per pound of lean body mass and engage in regular resistance training. Some athletes use targeted ketogenic diets (eating carbs around workouts) or cyclical ketogenic diets (carb refeeds) to optimize performance.

What are net carbs and why do they matter?

Net carbs are total carbohydrates minus fiber and sugar alcohols. Since fiber does not raise blood sugar or insulin levels, it does not prevent ketosis. Focus on net carbs (typically 20-50g daily) when tracking your intake. This allows you to eat fiber-rich vegetables while staying in ketosis.

How do I know if I am in ketosis?

Common signs of ketosis include: bad breath (fruity smell), reduced appetite, increased energy, weight loss, and better mental focus. For objective measurement, use urine test strips (cheap but less accurate), breath ketone meters, or blood ketone meters (most accurate). Aim for 0.5-3.0 mmol/L blood ketones for nutritional ketosis.

Is the ketogenic diet safe for everyone?

Keto is generally safe for healthy adults, but consult your doctor if you have Type 1 diabetes, Type 2 diabetes on medication, high blood pressure, kidney disease, liver disease, or are pregnant/breastfeeding. People taking diabetes or blood pressure medication may need dosage adjustments to avoid hypoglycemia.

A ketogenic macro split is defined by one constraint and one target: carbohydrate low enough to shift the body towards ketone production, and protein high enough to preserve lean mass without being so high that it undermines the first goal. Fat then fills the remaining energy. This calculator sets protein from lean body mass rather than total weight, which is the more defensible approach and the reason it asks for body fat percentage.

The formula

Lean body mass = weight x (1 - body fat % / 100)
BMR (Katch-McArdle) = 370 + (21.6 x lean body mass in kg)
TDEE = BMR x activity factor
Protein = 0.6 to 1.0 g per lb of lean mass
Carbohydrate = fixed limit, commonly 20 to 50 g/day
Fat = remaining calories / 9

Protein and carbohydrate provide 4 calories per gram, fat 9
The Katch-McArdle equation uses lean mass, so it needs a body fat estimate but handles muscular and lean bodies better than weight-based equations

Katch-McArdle basal metabolic rate equation. Carbohydrate thresholds for nutritional ketosis follow the range used in the clinical and research literature rather than a single defined cut-off.

How the numbers are derived

Basal metabolic rate is estimated from lean body mass, because muscle and organ tissue account for nearly all resting energy expenditure while fat tissue accounts for very little. That is why the Katch-McArdle equation is preferred here over weight-based equations such as Mifflin-St Jeor: two people at the same weight with different body composition have genuinely different resting requirements.

Protein is then set per pound of lean mass rather than total weight, for the same reason. Setting protein from total weight overshoots substantially in people carrying more fat, and overshooting protein matters on a ketogenic diet because surplus amino acids can be converted to glucose.

Carbohydrate is a fixed ceiling rather than a percentage, which is the part people most often get wrong. A percentage-based carbohydrate target scales with total intake, so a large eater on "5 percent carbs" can exceed the ketogenic threshold in absolute grams while believing they are compliant.

Typical targets

The ranges below are those in common use. There is no single validated threshold for nutritional ketosis, and individual carbohydrate tolerance varies with activity, muscle mass and insulin sensitivity.

Net carbohydrate normally means total carbohydrate minus fibre, and in some conventions minus sugar alcohols. The convention used changes the number substantially.
Fat is what fills the gap. Eating fat beyond that gap does not deepen ketosis; it simply adds calories.

Macro	Typical ketogenic target	Notes
Carbohydrate	20 to 50 g net per day	Lower end for induction; some tolerate more once adapted
Protein	0.6 to 1.0 g per lb lean mass	Higher end when training or in a deficit to preserve muscle
Fat	Remainder of calories	The balancing item, not a target in itself
Ketones (beta-hydroxybutyrate)	0.5 to 3.0 mmol/L	The commonly cited nutritional ketosis range

Adaptation and common problems

The first one to two weeks commonly bring headache, fatigue, irritability, muscle cramps and poor exercise tolerance. Most of this is not the absence of glucose but the loss of sodium and water: lowering carbohydrate lowers insulin, which increases renal sodium excretion, and fluid follows. Deliberate sodium, potassium and magnesium intake addresses most of these symptoms directly.

Constipation is the other frequent complaint, and it usually reflects the loss of fibre-bearing foods rather than the diet itself. Low-carbohydrate vegetables, nuts and seeds keep fibre intake reasonable without threatening the carbohydrate ceiling.

Limitations

The calculation depends on a body fat estimate, which is itself uncertain. Consumer bioimpedance scales commonly err by several percentage points, and that error propagates into every downstream figure.
BMR equations estimate a population average. Individual resting energy expenditure varies around any equation by roughly 10 percent even when lean mass is known accurately.
There is no single carbohydrate threshold for ketosis. Individual tolerance varies with activity, muscle mass and insulin sensitivity.
Ketogenic diets are used clinically for drug-resistant epilepsy under supervision. Self-directed use for other purposes has a much weaker evidence base, and long-term data are limited.
They are not appropriate for people with type 1 diabetes without close supervision, for those on SGLT2 inhibitors because of ketoacidosis risk, in pregnancy, or with pancreatitis, liver failure or certain rare metabolic disorders.
Anyone taking insulin or sulfonylureas needs medication adjustment before reducing carbohydrate, because hypoglycaemia risk rises sharply.

Frequently asked questions

How many carbs can I eat on keto?

Commonly 20 to 50 grams of net carbohydrate a day, with the lower end used for induction. There is no single validated threshold, and individual tolerance varies with activity level, muscle mass and insulin sensitivity.

Why does this calculator ask for body fat percentage?

Because it sets both metabolic rate and protein from lean body mass rather than total weight. Muscle and organ tissue drive resting energy expenditure while fat tissue contributes little, so two people at the same weight with different composition have different requirements.

Can I eat too much protein on keto?

Excess protein can be converted to glucose, which is why targets are set per pound of lean mass rather than total weight. In practice, moderate protein at 0.6 to 1.0 g per pound of lean mass preserves muscle without undermining ketosis for most people.

What causes keto flu?

Mostly sodium and fluid loss rather than lack of glucose. Lower carbohydrate means lower insulin, which increases renal sodium excretion, and water follows. Deliberate sodium, potassium and magnesium intake resolves most of the symptoms.

Do I need to hit my fat target exactly?

No. Fat is the balancing item that fills remaining calories, not a goal in itself. Eating beyond that does not deepen ketosis, it just adds energy, which matters if the aim is weight loss.