Keto Calculator

A keto calculator turns your body stats into daily macro targets. For a 35-year-old man who is 5 ft 10 in, weighs 185 lb, exercises a few days a week and wants to lose fat, it sets about 2,208 calories a day: 20 g net carbs, 134 g protein and 177 g fat, roughly 72% fat, 24% protein and 4% carbs, in grams you can track.

Keto sits in a family of body-stat tools. Use this page for a keto macro split; the Macro Calculator for a higher-carb split, the TDEE Calculator for maintenance calories alone, the Carb Calculator for a daily carb number on any diet, and the Protein Calculator for a protein target by goal.

How keto macros are calculated

The calculator works in four steps. First it estimates your resting calories with the Mifflin-St Jeor equation:

where s is +5 for men and −161 for women. It multiplies BMR by an activity factor (1.2 sedentary to 1.9 extra active, a convention rather than part of the equation) to get your TDEE, then applies your goal: cut (20% below), maintain, or bulk (10% above). A cut never drops below 1,200 calories a day for women or 1,500 for men, the lowest intakes the 2013 AHA/ACC/TOS obesity guideline uses for weight-loss diets. Finally it splits the calories the keto way: carbs are capped at your net-carb limit, protein is 1.6 g per kg of body weight, and fat fills the rest (fat has 9 calories per gram, protein and carbohydrate 4).

Keto macro calculation: a worked example

Here is every step for the calculator's default: male, 35, 5 ft 10 in, 185 lb, moderately active, cutting, 20 g net carbs.

What a ketogenic diet looks like

A 2025 StatPearls review describes three versions. The classic ketogenic diet for drug-resistant epilepsy gets about 90% of calories from fat and is run under medical supervision. The modified Atkins diet gets roughly 60% to 70% from fat, 25% to 30% from protein and 5% to 10% from carbohydrate, usually under 20 g. The very-low-carbohydrate ketogenic diet used for weight and blood sugar limits carbohydrate to 20 to 50 g a day with moderate protein and about 60% to 75% of calories from fat. This calculator models that last version. Keto keeps protein moderate rather than high, so the gram target here comes from your body weight instead of a percentage.

Keto macros by body weight (chart)

Computed keto targets on a cut (20% below maintenance) with a 20 g net-carb cap. Men assume 5 ft 10 in, women 5 ft 5 in, both age 35 and moderately active.

What are net carbs?

Net carbs are total carbohydrate minus fiber, and on some products also minus sugar alcohols such as erythritol. It is a diet term rather than a label term: the FDA Nutrition Facts panel (21 CFR 101.9) lists total carbohydrate, dietary fiber, total sugars and added sugars, and lets manufacturers list sugar alcohols as an optional line. Keto limits are usually counted as net carbs, which is why a label's total-carb number looks higher than what counts toward your cap. This calculator expresses the cap as net carbs: 20 g (strict), 30 g (moderate) or 50 g (liberal).

How to use this keto calculator

1. Units: choose imperial (lb, ft/in) or metric (kg, cm); switching converts your entries.
2. Sex, age, height, weight: these drive your BMR through the Mifflin-St Jeor equation.
3. Activity level: pick the option that matches a typical week. Overstating activity is the most common reason estimates run high.
4. Goal: cut to lose fat, maintain, or bulk to gain.
5. Net-carb limit: 20 g is the usual starting point; 30 or 50 g are more liberal settings.

The result updates as you type: your daily calorie target at the top, then fat, protein and net carbs in grams, calories and percent. If an entry is missing or out of range, the calculator says which one to fix.

Who this calculator is for

• Keto beginners who want clear daily gram targets to start with.
• People losing weight who want a keto plan with a calorie deficit and enough protein.
• Returning low-carbers who want to reset their macros to their current weight.
• Food trackers who need gram targets to enter in an app.

Key keto terms

• Ketosis: a metabolic state in which, with carbohydrate very low, the body shifts from glucose to ketone bodies as its main fuel.
• BMR: basal metabolic rate, the calories you burn at complete rest.
• TDEE: total daily energy expenditure, BMR plus everything you do in a day; your maintenance level.
• Net carbs: total carbohydrate minus fiber (and on some products sugar alcohols).
• Keto flu: the popular name for headache, fatigue and other symptoms some people report in the first weeks.

Scenario 1: losing fat on strict keto

A 32-year-old woman who is 5 ft 5 in, weighs 160 lb and is lightly active has a TDEE of about 1,975 calories. On a cut that drops to about 1,580 calories. With a 20 g net-carb cap and protein of 116 g, fat fills the rest at about 115 g, roughly 66% fat, 29% protein and 5% carbs. At a lower calorie target the protein share rises and the fat share falls, because protein is set in grams.

Scenario 2: maintaining on a liberal carb cap

A 28-year-old man who is 6 ft 0 in, weighs 200 lb, is very active and chooses maintain has a TDEE of about 3,304 calories. With a 50 g net-carb cap and protein of 145 g, fat fills the rest at about 280 g, close to 76% fat, 18% protein and 6% carbs.

Keto for weight loss vs maintenance: macros by goal

Same person, three goals: the reference man (5 ft 10 in, 185 lb, 35, moderately active, 20 g net carbs). Only the calorie target and fat move; protein and carbs stay fixed.

Raising the carb cap from 20 g to 50 g on the cut target trades about 13 g of fat (177 g down to about 163 g) for the extra 30 g of carbs, because calories stay fixed at 2,208.

Building meals around your macros

The easiest way to hit the numbers is to build each plate in the same order the calculator builds your macros: protein first, then fat, then carbs from vegetables. Start with a protein source such as eggs, poultry, fish or meat, add a fat such as olive oil, butter, avocado, cheese or nuts, and round it out with low-carb vegetables like leafy greens, zucchini, broccoli or peppers. Because fat has 9 calories per gram, a tablespoon of oil or a handful of nuts moves your total quickly, so it pays to measure the fats you cook with. Logging a planned day in a tracking app before you eat it is the fastest way to learn what your targets look like on a plate.

Keto vs. other low-carb diets

Keto is the strictest branch of the low-carb family. The very-low-carbohydrate ketogenic diet keeps carbs around 20 to 50 g a day; the modified Atkins diet starts below 20 g; and general low-carb eating allows more carbohydrate than either, usually without aiming for ketosis. For weight loss, the 2019 National Lipid Association statement found that low- and very-low-carbohydrate diets are not superior to other approaches, though they may help some people control appetite and lower triglycerides; their effect on LDL cholesterol was mixed, and data beyond 2 years are limited. The right plan is the one you can follow while meeting your nutrient needs, so a gentler carb target may suit you better if you do not need ketosis.

How to use the result in real life

Treat the three numbers as a daily budget. Enter them in a food-tracking app as custom goals and log meals against them for the first two or three weeks. Treat net carbs as the hard limit, protein as a target to reach, and fat as a flexible ceiling, especially when cutting, since body fat supplies part of the day's energy. Weigh yourself a few times a week under the same conditions and average the readings; if the trend is not moving after two to three weeks, check that your activity setting is honest and adjust fat first. The Weight Loss Calculator turns a calorie deficit into a timeline.

What changes your keto macros the most

• Calorie target: the biggest driver; your goal and activity level set the total that fat must fill.
• Body weight: protein scales with it, which changes how many calories are left for fat.
• Carb cap: going from 20 to 50 g trades a little fat for carbs without changing total calories.
• Activity factor: moving from sedentary to very active adds several hundred calories, almost all as fat.
• Sex and age: both shift BMR, so identical height and weight can give different targets.

Tips to hit your keto targets

• Plan fat sources: olive oil, avocado, fatty fish, nuts and dairy make the fat target realistic.
• Anchor each meal with protein: it is the macro most people fall short on when they focus on fat.
• Spend carbs on vegetables: leafy greens and other low-carb vegetables add fiber within your cap.
• Watch hidden carbs: sauces, dressings and "low-carb" snacks can use up a 20 g cap quickly.
• Use the fat number as a ceiling when cutting: on a deficit you do not need to eat every gram.

Limitations and assumptions

• BMR uses Mifflin-St Jeor, which a 2005 review found most likely to land within 10% of measured resting metabolism; individuals can still be further off.
• Protein is based on total body weight; people with high body fat may prefer a lower figure based on lean mass.
• It assumes you stay under your net-carb cap, and it cannot tell you whether you are in ketosis.
• It does not plan electrolytes, fiber or micronutrients, and it cannot account for medications or medical conditions.
• Results are a starting point; check them against your weight trend over 2 to 3 weeks.

How it compares to related calculators

• For a non-keto macro split, use the Macro Calculator.
• For daily calories only, use the Calorie Calculator; for maintenance, the TDEE Calculator; for resting calories, the BMR Calculator.
• For a protein target by goal, use the Protein Calculator; for a daily carb number, the Carb Calculator.
• To estimate lean mass first, use the Body Fat Calculator.

Sources

• Daley SF, Masood W, Annamaraju P, Khan Suheb MZ, The Ketogenic Diet: Clinical Applications, Evidence-based Indications, and Implementation, StatPearls (updated December 2025): PubMed 29763005.
• Kirkpatrick CF et al. (2019), National Lipid Association scientific statement on low- and very-low-carbohydrate diets: PubMed 31611148.
• Evert AB et al. (2019), Nutrition Therapy for Adults With Diabetes or Prediabetes: A Consensus Report (American Diabetes Association): PMC7011201.
• Bostock ECS et al. (2020), consumer reports of keto flu: PMC7082414.
• U.S. Departments of Agriculture and Health and Human Services: Dietary Guidelines for Americans, 2025-2030 (protein goal of 1.2 to 1.6 g/kg; lower-carbohydrate diets for some chronic diseases).
• Mifflin MD, St Jeor ST et al. (1990): PubMed 2305711; Frankenfield D et al. (2005): PubMed 15883556; Morton RW et al. (2018): PubMed 28698222.
• Jensen MD et al. (2014), 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults: PubMed 24222017.
• Code of Federal Regulations: 21 CFR 101.9, Nutrition labeling of food (label carbohydrate lines and the 4/4/9 calorie factors).