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Ketogenic Diet Macro Calculator
Calculate your optimal keto macros for ketosis and fat adaptation.
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Try an Example
Pick a scenario to see how the calculator works, then adjust the values
Muscle Building
High-protein plan for a moderately active male aiming to gain lean mass
Key values: 30yo male · 80 kg · +15% surplus
Weight Loss
Balanced deficit plan for a lightly active female targeting steady fat loss
Key values: 28yo female · 65 kg · -25% deficit
Keto Diet
Very low carb, high fat plan for metabolic adaptation
Key values: 35yo male · 90 kg · Ketogenic
What Is Ketosis?
When carbohydrate intake drops below approximately 20–50 grams per day, the body depletes its glycogen stores and shifts to burning fat as its primary fuel. The liver converts fatty acids into ketone bodies (acetoacetate, beta-hydroxybutyrate, acetone), which the brain and muscles use for energy.
Standard Keto Macro Ratios
| Macro | % of calories | Grams (on 2,000 cal) | Cal per gram |
|---|---|---|---|
| Fat | 70–75% | 156–167 g | 9 |
| Protein | 20–25% | 100–125 g | 4 |
| Carbohydrates | 5–10% | 25–50 g | 4 |
The carb limit is the defining constraint. Everything else adjusts around it.
Calculating Your Keto Macros
- Set carbs: 20–50 g/day (start at 20 for reliable ketosis).
- Set protein: of lean body mass.
- Fill the rest with fat:
Example: 1,800 cal target, 120 g protein, 25 g carbs:
Net Carbs vs. Total Carbs
Fiber and certain sugar alcohols are not digested and don't raise blood sugar significantly. Many keto practitioners count net carbs:
Caution: Not all sugar alcohols are equal. Erythritol has virtually zero glycemic impact and can be fully subtracted. Maltitol has a substantial glycemic impact and should be only partially subtracted.
Keto Adaptation Timeline
| Phase | Duration | What happens |
|---|---|---|
| Glycogen depletion | 1–3 days | Body burns stored glycogen; water weight drops |
| Keto flu | 3–7 days | Fatigue, headaches as metabolism shifts; electrolyte loss |
| Early ketosis | 1–2 weeks | Ketone production ramps up; energy stabilizes |
| Fat-adapted | 3–6 weeks | Efficient fat/ketone burning; sustained energy, reduced cravings |
Performance (especially high-intensity exercise) may dip during the first 2–4 weeks before adaptation restores it. Endurance exercise often recovers fully; peak power may remain slightly reduced.
Frequently Asked Questions
How many carbs can I eat on keto?
Most people enter ketosis at 20 to 50 grams of net carbs per day. Starting at 20 grams provides the most reliable entry into ketosis. Net carbs are total carbs minus fiber and non-digestible sugar alcohols.
What is ketosis?
Ketosis is a metabolic state where the body shifts from burning glucose to burning fat as its primary fuel. The liver converts fatty acids into ketone bodies, which the brain and muscles use for energy when carbohydrate intake is very low.
How long does it take to get into ketosis?
Glycogen depletion takes 1 to 3 days, followed by the “keto flu” phase (fatigue, headaches) lasting 3 to 7 days. Early ketosis begins at 1 to 2 weeks, and full fat adaptation takes 3 to 6 weeks with sustained energy and reduced cravings.
What is the difference between net carbs and total carbs?
Net carbs equal total carbs minus fiber and certain sugar alcohols. Fiber is not digested and does not raise blood sugar. However, not all sugar alcohols are equal. Erythritol can be fully subtracted, but maltitol has substantial glycemic impact and should only be partially subtracted.
How do I calculate my fat intake on keto?
Set carbs first (20-50 g), then protein ( g/kg lean body mass), then fill the remaining calories with fat. The formula is: .
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