Standard ketogenic macro ratios are approximately 70–75% fat, 20–25% protein, and 5% carbohydrates by calories. For a 2,000-calorie diet: 155–167g fat, 100–125g protein, and 25g carbs maximum. Most people achieve and maintain ketosis by limiting net carbs to 20–50g per day. Too much protein can also prevent ketosis via gluconeogenesis — precision matters on keto.
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What Is a Keto Macro Calculator?
A keto macro calculator determines the specific daily targets for fat, protein, and net carbohydrates needed to enter and maintain nutritional ketosis, based on your calorie needs, body weight, and goal.
The ketogenic diet shifts the body's primary energy source from glucose (derived from carbohydrates) to ketone bodies produced by the liver from dietary and stored fat. This metabolic state — ketosis — requires carbohydrate intake to be very low (typically under 20–50g net carbs per day), forcing the body to rely on fat for fuel.
Calculating keto macros differs from standard macro calculation because carbs are the binding constraint. First, net carbs are set at 20–25g for reliable ketosis. Protein is then set at a moderate level — 1.2–1.7g per kg of lean body mass — keeping it high enough to preserve muscle but low enough to avoid excess gluconeogenesis, where protein converts to glucose and disrupts ketosis. All remaining calories are filled with fat.
Net carbs are calculated by subtracting dietary fiber from total carbohydrates: fiber is not digested or converted to glucose, so it does not impact ketosis. Sugar alcohols like erythritol are also typically subtracted, while maltitol and sorbitol have higher glycemic impact and are usually counted. Getting this distinction right is important — foods that look keto-friendly by total carbs may have too many net carbs to maintain ketosis.
Calculating Keto Macros Step by Step
Step 1: Calculate Total Daily Energy Expenditure (TDEE) Use the Mifflin-St Jeor formula (or the Calorie Calculator) to find your maintenance calories, then adjust for goal:
- Weight loss: maintenance − 20%
- Maintenance: maintenance calories
- Muscle gain: maintenance + 10%
Step 2: Set carb target (strictest constraint)
Net Carbs = 20–50g per day (most people: 20–25g for reliable ketosis)
Carb Calories = Net Carbs × 4 = 80–200 calories
Step 3: Set protein (moderate — not too high)
Protein = 1.2–1.7 g/kg lean body mass (not total weight)
Protein Calories = Protein grams × 4
Too much protein promotes gluconeogenesis (protein converted to glucose), which can slow or prevent ketosis. The protein range is lower than for standard high-protein diets.
Step 4: Fill remaining calories with fat
Fat Calories = Total Calories − Carb Calories − Protein Calories
Fat Grams = Fat Calories ÷ 9
Example (70kg woman, 20% body fat, 1,800 cal weight loss goal):
- Lean body mass = 70 × 0.80 = 56 kg
- Net carbs: 25g × 4 = 100 calories
- Protein: 56 × 1.5 = 84g × 4 = 336 calories
- Fat: (1,800 − 100 − 336) ÷ 9 = 1,364 ÷ 9 = 152g fat
Final macros: 25g carbs / 84g protein / 152g fat
Net Carbs vs. Total Carbs
Net carbs = Total carbs − Dietary fiber − Sugar alcohols (partially)
Fiber is not digested and does not raise blood sugar or impact ketosis. Sugar alcohols (like erythritol and xylitol) have minimal blood sugar impact. Maltitol and sorbitol have higher glycemic impact and should be subtracted partially or not at all.
| Food | Total Carbs | Fiber | Net Carbs | |------|------------|-------|-----------| | Avocado (1 medium) | 17g | 13g | 4g | | Broccoli (1 cup) | 6g | 2.4g | 3.6g | | Almonds (1 oz) | 6g | 3.5g | 2.5g | | Berries (1/2 cup) | 9g | 2g | 7g | | White bread (1 slice) | 14g | 0.6g | 13.4g |
Keto-Friendly Foods
High fat, low carb:
- Avocados, olive oil, coconut oil, butter, ghee
- Fatty fish: salmon, mackerel, sardines
- Full-fat dairy: cheese, heavy cream, Greek yogurt (small amounts)
- Nuts and seeds: walnuts, pecans, macadamia, chia seeds
Moderate protein:
- Meat and poultry, eggs, seafood
Low-carb vegetables:
- Leafy greens, broccoli, cauliflower, zucchini, asparagus, Brussels sprouts
Foods to eliminate:
- Grains, bread, pasta, rice
- Sugary foods and drinks
- Most fruits (berries in moderation are acceptable)
- High-starch vegetables: potatoes, corn, beets
Frequently Asked Questions
How long does it take to enter ketosis? Most people enter ketosis within 2–4 days of strict carbohydrate restriction (under 20–30g net carbs/day), provided glycogen stores are depleted. Glycogen depletion happens faster with exercise. Full "keto adaptation" — where the body efficiently uses fat and ketones for fuel and mental clarity returns after initial fatigue — takes 2–6 weeks. The first week often involves the "keto flu" (fatigue, headaches, irritability) as the body transitions metabolism.
What are electrolytes and why do they matter on keto? Reducing carbohydrates causes the kidneys to excrete more sodium (because insulin levels fall and the kidneys retain less sodium). This leads to increased excretion of sodium, potassium, and magnesium — the "keto flu" is largely electrolyte depletion. Supplementing these minerals reduces or eliminates keto flu symptoms: Sodium: 2,000–3,000mg/day (more than typical diet recommendations, especially if exercising); Potassium: 3,500–4,700mg/day; Magnesium: 300–500mg/day. Many people use salt, lite salt (potassium), and magnesium glycinate.
Can you build muscle on keto? Research is mixed. Building muscle requires adequate protein and a slight calorie surplus (or at least maintenance). Carbohydrates aid insulin signaling for muscle protein synthesis. Some studies show keto can maintain but not optimally build muscle; others show comparable muscle gain when protein is sufficient. Most bodybuilders and athletes prioritize muscle gain over metabolic benefits and use higher-carbohydrate protocols. For those specifically interested in body recomposition (muscle gain + fat loss simultaneously), carb cycling (standard keto with strategic carb refeeds) may be a better approach.
How do I know if I'm in ketosis? Methods: Blood ketone meter (finger prick, measures beta-hydroxybutyrate; most accurate; 0.5+ mmol/L = ketosis); Urine ketone strips (measure acetoacetate; accurate in first weeks, less so when keto-adapted as urine ketones decrease); Breath meters (measure acetone; moderately accurate, no consumables); Symptoms: reduced appetite, increased energy and mental clarity (after adaptation), sweet/fruity breath (acetone).
Is the ketogenic diet safe long-term? Research on long-term (>2 years) ketogenic diets in healthy individuals is limited. Short and medium-term research shows: improved insulin sensitivity, weight loss, and triglyceride reduction. Some studies show increased LDL cholesterol. Very high fat intake raises safety questions for some individuals. Keto restricts fiber-rich whole grains and many fruits — important for gut microbiome diversity and long-term health. Most experts recommend keto as a short-to-medium term therapeutic tool rather than a lifelong eating pattern, unless medically indicated (epilepsy, type 2 diabetes management under medical supervision).
Related Free Tools on RoughTools
- Macro Calculator — calculate macros for standard (non-keto) diets
- Calorie Calculator — find your TDEE for keto calorie target
- Body Fat Percentage Calculator — calculate lean body mass for protein target
Calculate Your Keto Macros Now
The free Keto Macro Calculator at RoughTools calculates personalized fat, protein, and net carb targets for ketosis based on your calorie needs, lean body mass, and weight goal. No account needed, completely free.