Starting a ketogenic diet requires a clear understanding of your macronutrient targets specifically, how many grams of fat, protein, and carbohydrates you need each day to achieve and maintain nutritional ketosis. A Keto Calculator takes your personal stats sex, height, weight, age, activity level, and goal weight and calculates a daily calorie target adjusted for weight loss, then splits those calories into the classic keto macro ratio of 75% fat, 20% protein, and 5% carbohydrates. Whether you are beginning keto for weight loss, metabolic health, or therapeutic reasons, having precise gram targets for each macronutrient removes the guesswork and helps you structure meals that keep you in ketosis. Toolraxy provides a free, client-side Keto Calculator that delivers your complete macro breakdown in a clear, color-coded format.
How to Use the Keto Calculator
Select your sex by clicking the Female or Male button.
Enter your height in centimeters, current weight in kilograms, and age in years.
Choose your activity level from the dropdown, ranging from sedentary to extremely active.
Enter your target weight in kilograms.
Select your diet pace: Normal (0.5 kg loss per week) or Strict (1 kg loss per week). The calorie display updates to show your adjusted daily target.
Click Calculate. The tool displays your daily calorie target and a complete macro breakdown showing fat, carbohydrate, and protein targets in both calories and grams, with percentage headers for each macronutrient.
How the Tool Works
This Keto Calculator uses the Mifflin-St Jeor equation to estimate Basal Metabolic Rate, multiplies by an activity factor for TDEE, applies a weight-loss deficit based on the current and target weight difference, and then splits the resulting calorie target into the standard ketogenic macronutrient ratio.
BMR Calculation (Mifflin-St Jeor Equation):
For males:
BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
For females:
BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
TDEE and Calorie Target:
TDEE = BMR × Activity Factor (1.2 to 1.9). The weight difference is calculated as Current Weight – Target Weight. If the target weight is lower than the current weight, a daily deficit is applied: Normal pace = 500 kcal deficit, Strict pace = 1,000 kcal deficit. The target calories are TDEE minus the deficit, with a floor of 1,200 kcal/day. The calculated calorie target is displayed in a read-only field.
Keto Macronutrient Split:
The classic ketogenic diet macronutrient ratio is applied as fixed percentages of the calorie target:
Fat: 75% of calories. Fat grams = (Calorie target × 0.75) ÷ 9, rounded. Fat provides 9 kcal per gram.
Carbohydrates: 5% of calories. Carbohydrate grams = (Calorie target × 0.05) ÷ 4, rounded. Carbohydrates provide 4 kcal per gram. This typically results in 20–30 grams of carbs per day, consistent with standard ketogenic diet guidelines.
Protein: 20% of calories. Protein grams = (Calorie target × 0.20) ÷ 4, rounded. Protein provides 4 kcal per gram.
The results are displayed in three distinct macro cards, each showing the calorie contribution and gram target for that macronutrient, with percentage headers for quick reference.
Worked Example
Consider a 30-year-old male who is 170 cm tall, weighs 70 kg, has a target weight of 65 kg, is lightly active, and chooses a normal diet pace:
Male Mifflin-St Jeor BMR: (10 × 70) + (6.25 × 170) – (5 × 30) + 5 = 700 + 1,062.5 – 150 + 5 = 1,617.5, rounded to 1,618 kcal/day.
Lightly active TDEE: 1,618 × 1.375 = 2,224.75, rounded to 2,225 kcal/day.
Weight difference: 70 – 65 = 5 kg (weight loss needed). Normal deficit: 500 kcal.
Target calories: 2,225 – 500 = 1,725 kcal/day (displayed as 1,725 kcal/day).
Fat (75%): 1,725 × 0.75 = 1,293.75, rounded to 1,294 kcal. Fat grams: 1,294 ÷ 9 = 143.8, rounded to 144 grams.
Carbohydrates (5%): 1,725 × 0.05 = 86.25, rounded to 86 kcal. Carb grams: 86 ÷ 4 = 21.5, rounded to 22 grams.
Protein (20%): 1,725 × 0.20 = 345 kcal. Protein grams: 345 ÷ 4 = 86.25, rounded to 86 grams.
Final keto macros: 144g fat, 22g carbs, 86g protein, totaling 1,725 calories.
If the same person chose the strict pace (1,000 kcal deficit), the target would be 1,225 kcal, fat would be 102 grams (920 kcal), carbs would be 15 grams (60 kcal), and protein would be 61 grams (245 kcal). The 22-gram carb target on the normal pace and 15-gram target on the strict pace are both well within the standard ketogenic guideline of under 30–50 grams of carbohydrates per day for maintaining nutritional ketosis.
Benefits of Using This Keto Calculator
Saves time by applying the Mifflin-St Jeor equation and the standard keto macro split automatically.
Adjusts calorie targets based on the weight difference between current and goal weight.
Provides clear gram and calorie targets for all three macronutrients in a color-coded format.
Offers two diet paces for flexible weight loss planning.
Free and private, with all calculations running in your browser.
Uses a fixed 75/20/5 macro ratio consistent with established ketogenic diet protocols.
FAQs
How accurate is this keto calculator?
The calculator uses the Mifflin-St Jeor equation for BMR and the standard 75/20/5 ketogenic macro split. It provides reliable starting targets. Individual responses to keto vary, and you may need to adjust macros based on your results and how you feel.
Can I change the macro percentages?
This calculator uses the fixed 75/20/5 keto ratio. If you need a different split—such as a higher-protein ketogenic diet—use a custom macro calculator where you can set your own percentages.
What if my target weight is higher than my current weight?
If your target weight is equal to or greater than your current weight, no deficit is applied. The calculator will provide maintenance-level keto macros.
How many grams of net carbs should I aim for on keto?
The calculator provides total carbohydrate grams. For net carbs, subtract fiber from total carbs. Most keto guidelines recommend 20–30 grams of net carbs per day. The 5% allocation typically keeps total carbs in this range.
Why does the calculator use a 500 or 1,000 calorie deficit?
A 500 kcal daily deficit produces approximately 0.5 kg of weight loss per week. A 1,000 kcal deficit produces approximately 1 kg per week. These are standard, sustainable rates. The minimum calorie target of 1,200 kcal prevents excessively low intakes.
Can I use this calculator if I am already at my goal weight?
Yes. Enter your current weight as both your current and target weight. The calculator will provide maintenance-level keto macros with no deficit applied.
Does this calculator account for exercise calories?
Exercise is accounted for through the activity level multiplier. Do not eat back exercise calories on top of the calculated target, as the TDEE already includes your activity.
Can I share my keto macro results?
Yes. Use the Copy button to copy all results, or the Share button to send a summary that includes your calorie target, fat, carb, and protein grams.
Does this calculator store my personal data?
No. All calculations run entirely in your browser. No personal health data is saved or transmitted.
Is this calculator a substitute for professional dietary advice?
No. This tool provides estimates for educational purposes. The ketogenic diet may not be appropriate for everyone, particularly individuals with certain medical conditions. Consult a healthcare professional or registered dietitian before beginning a ketogenic diet.
