Keto calculator
Your keto macros in 30 seconds: enter your details and get calories, protein and fat for your goal. Everything runs in your browser — we store nothing.
Method: BMR via Mifflin-St Jeor — or Katch-McArdle when you enter body fat % — × activity factor, adjusted by goal. Carbs fixed at 25 g net, protein 1.6 g/kg, fat fills the remaining calories.
Informational content, not medical advice. If symptoms are severe or last more than a week, see a healthcare professional.
What you enter
- Your details: sex, age, height and weight — plus body fat % if you know it.
- Daily movement: from desk job to intense daily training.
- Your goal: lose fat, maintain, or build muscle.
What you get
- Calories: your daily energy target, adjusted for your goal.
- Carbs: capped at 25 g net per day — the ceiling that keeps most people in ketosis.
- Protein: 1.6 g per kg of body weight, to hold on to muscle while losing fat.
- Fat: the rest of your calories — your main fuel on keto.
How the keto macro calculator works
Your base burn (BMR) comes from the Mifflin-St Jeor equation — the one dietitians use — multiplied by an activity factor. If you enter your body fat %, the calculator switches to Katch-McArdle, which works from lean mass and is more accurate for very muscular or very lean bodies.
As a keto calculator for weight loss it applies a moderate −20 % deficit: fast enough to see results, sustainable enough to keep them. To gain muscle it adds +10 %. Then macros: net carbs stay capped, protein scales with your body, and fat fills the remaining calories.
Net carbs: why the limit is 20–25 g
Net carbs are total carbohydrates minus fiber (and sugar alcohols like erythritol): fiber doesn't raise blood glucose, so keto only counts what's left. Unlike calories, the carb ceiling barely changes with body size — 20–25 g net per day puts almost everyone into nutritional ketosis, which is why the calculator fixes it instead of scaling it.
Keto calculator FAQ
Is there a free keto calculator?
Yes — this one. It's free, runs entirely in your browser and doesn't ask for an email or sign-up. Enter your details and you get calories, net carbs, protein and fat instantly.
How do I calculate my keto carb limit?
You don't need a formula: nutritional ketosis kicks in at 20–25 g of net carbs per day for nearly everyone, regardless of size. That's why this calculator fixes carbs at 25 g and builds calories, protein and fat around them.
What are net carbs?
Total carbohydrates minus fiber and sugar alcohols like erythritol. Fiber doesn't raise blood glucose, so keto counts what's left: a food with 8 g of carbs and 5 g of fiber has 3 g net.
How many calories should I eat on keto?
Your maintenance calories (BMR × activity) adjusted for your goal: about −20 % to lose fat, unchanged to maintain, +10 % to gain muscle. That's exactly what the calculator computes.
How much protein should I eat on keto?
About 1.6 g per kg of body weight — enough to preserve muscle while losing fat. The idea that this much protein kicks you out of ketosis is a myth.
How much fat should I eat on keto?
Fat fills the calories left after carbs and protein. It's a lever, not a target: if you're satisfied below the number, stay there — eating fat for its own sake slows fat loss.
What is the keto macro ratio?
Typically around 70 % fat, 25 % protein and 5 % carbs by calories. But grams beat percentages: 25 g net carbs is a hard cap, protein scales with your body, and fat moves with your goal.
Should I enter my body fat percentage?
If you know it, yes. The calculator then switches from Mifflin-St Jeor to Katch-McArdle, which is based on lean mass and more accurate for very muscular or very lean bodies.
Do calories matter on keto?
Yes. Ketosis reduces hunger, which makes a deficit much easier to sustain — but it doesn't suspend energy balance. That's why the weight-loss setting uses a moderate −20 % deficit.
How fast will I lose weight on keto?
The first week is mostly water — 2–4 kg is common as glycogen empties. After that, a realistic pace on the calculated deficit is 0.5–1 % of body weight per week.
When should I recalculate my macros?
Every 4–5 kg lost, or whenever your activity changes. Calorie needs drop as you get lighter; running months on old numbers is the most common reason for a stall.
Can I build muscle on keto?
Yes — pick "Gain muscle" and the calculator adds a +10 % surplus. Keep protein at the calculated target and lift; ketosis doesn't prevent hypertrophy.
Do I count net or total carbs?
Net carbs, if you eat whole foods — vegetables, nuts and berries are fine by net count. Counting total carbs is a stricter variant some people prefer with processed "keto" products full of sweeteners.
Is the calculator accurate for women?
Mifflin-St Jeor and Katch-McArdle account for sex, age, weight and height. Hormonal shifts (like menopause) can lower real-world needs slightly — if fat loss stalls, recalculate using the "Sedentary" level.
What formula does this keto calculator use?
BMR via Mifflin-St Jeor (10×kg + 6.25×cm − 5×age, +5 men / −161 women) — or Katch-McArdle (370 + 21.6 × lean mass) when you enter body fat — times an activity factor, adjusted by goal. Carbs fixed at 25 g net, protein 1.6 g/kg, fat fills the rest.
What's the easiest way to actually hit these macros?
Tracking is the hard part, not the math. The Ketorai app scans your plate with AI and tells you the net carbs and whether it's keto — no weighing, no database digging.
