Keto calculator
This keto calculator turns your sex, age, height, weight, activity and goal into a daily calorie target, then splits it into keto macros: a fixed net carb cap, protein set from your body weight or lean mass, and fat filling the rest. You get grams, calories and the percentage of your day for each macro, with the working shown.
65% fat, 29% protein, 6% net carbs. 25 g net carbs sits inside the 20 to 50 g a day that brings most people into ketosis.
How this keto macro calculator works
A ketogenic diet is defined by one number first: how few carbohydrates you eat. Everything else follows from that cap and from your calorie target. The calculator works in four steps, in this order.
Step 1: calories from your BMR and activity
Resting energy expenditure comes from the Mifflin St Jeor equation: 10 x weight in kg plus 6.25 x height in cm minus 5 x age, plus 5 for men or minus 161 for women. That is multiplied by an activity factor from 1.2 (desk job, no training) to 1.9 (physical job or two sessions a day), then by your goal: a 10 to 25% deficit to lose fat, no change to maintain, or a 5 to 15% surplus to gain. These are the same equation and multipliers as our macro calculator and TDEE calculator, so the calorie number matches across tools.
Step 2: net carbs as a fixed gram cap
Carbs are not a percentage here. They are a fixed number of grams, 25 g by default and adjustable from 20 to 50 g, because ketosis depends on the absolute amount of carbohydrate, not its share of a calorie total. 25 g is the same at 1,500 kcal as at 3,000 kcal.
Step 3: protein from body weight or lean mass
Protein is set in grams per kg: 1.2, 1.6 or 2.0 g per kg of body weight. If you enter a body fat percentage, the calculator switches to lean mass and uses 1.5, 2.0 or 2.5 g per kg of lean mass instead, which avoids overshooting protein for someone carrying a lot of body fat.
Step 4: fat fills the rest
Fat is whatever calories remain after protein (4 kcal per gram) and net carbs (4 kcal per gram), divided by 9 kcal per gram. On a keto diet fat is the lever, not a target to force: in a deficit, part of the fat you burn comes from your own body.
Worked example
A 32 year old woman, 168 cm, 70 kg, lightly active, losing at a 20% deficit. BMR is 10 x 70 + 6.25 x 168 minus 5 x 32 minus 161 = 1,429 kcal. Multiply by 1.375 for activity and 0.80 for the deficit: about 1,570 kcal a day. Protein at 1.6 g/kg is 112 g (448 kcal), net carbs 25 g (100 kcal), and fat is (1,570 minus 448 minus 100) / 9 = 114 g. That is 65% fat, 29% protein and 6% net carbs.
Keto macro ratio and keto macro percentages
Most keto guides quote a fixed keto macro ratio such as 70% fat, 20% protein and 10% carbs. Those percentages are a description of a typical outcome, not the way to set a plan. Because carbs and protein are fixed in grams, the percentages shift as calories change: a smaller person in a deficit ends up with a lower fat share and a higher protein share than a large, active person on the same food.
The ratios below are the common versions you will see. The classic 4:1 ratio comes from clinical epilepsy treatment and is far stricter than anything needed for weight management.
| Version | Fat | Protein | Carbs |
|---|---|---|---|
| Standard keto | 70 to 80% | 15 to 20% | 5 to 10% |
| Higher protein keto | about 60 to 65% | about 30% | 5 to 10% |
| Metabolic ward study (Hall 2016) | 80% | 15% | 5% |
| Classic 4:1 epilepsy diet | about 90% | about 6% | about 4% |
Keto diet macros at different calorie targets
This table holds net carbs at 25 g and protein at 112 g (1.6 g/kg for a 70 kg person) and lets fat absorb the calorie difference. It shows why the same macros for keto produce very different percentages: at 1,400 kcal fat is 61% of the day, at 2,400 kcal it is 77%.
Neither end is more or less ketogenic. Ketosis follows the carbohydrate cap, so both days keep you in the same metabolic state as long as net carbs stay low.
| Calories | Fat | Protein | Net carbs |
|---|---|---|---|
| 1,400 kcal | 95 g, 61% | 112 g, 32% | 25 g, 7% |
| 1,600 kcal | 117 g, 66% | 112 g, 28% | 25 g, 6% |
| 1,800 kcal | 139 g, 70% | 112 g, 25% | 25 g, 6% |
| 2,000 kcal | 161 g, 73% | 112 g, 22% | 25 g, 5% |
| 2,400 kcal | 206 g, 77% | 112 g, 19% | 25 g, 4% |
Carb calculator for keto: how many net carbs per day
A very low carbohydrate ketogenic diet is usually defined as 20 to 50 g of carbohydrate a day, or under 10% of a 2,000 kcal diet. That is the range the calculator allows. 20 to 25 g is the safe starting point for almost everyone; some people, especially active ones, stay in ketosis closer to 50 g.
Net carbs versus total carbs
Net carbs are total carbohydrate minus fibre. Fibre is not digested into glucose, so it does not count against the cap. In the US, food labels list fibre inside total carbohydrate, so you subtract it yourself. In the EU and UK, the carbohydrate line already excludes fibre, so the number on the label is effectively net carbs.
How to find your own limit
Start at 20 to 25 g for the first two to four weeks. If you want more room, raise net carbs by about 5 g a week and check whether you stay in ketosis. A blood beta hydroxybutyrate reading of 0.5 mmol/L or higher is the usual threshold for nutritional ketosis; urine strips become less reliable after the first weeks as the body adapts.
How much protein on keto
Protein needs do not change because you cut carbs. The International Society of Sports Nutrition puts the range for active people at 1.4 to 2.0 g per kg of body weight a day, and a meta analysis of resistance training studies found extra protein stopped adding measurable muscle gains at around 1.6 g/kg. The calculator offers 1.2 g/kg for a lower intake, 1.6 g/kg as the default and 2.0 g/kg for hard training or an aggressive deficit, where a higher intake helps protect muscle.
If you know your body fat percentage, entering it gives a better number. A 100 kg person at 40% body fat does not need 160 g of protein: on 60 kg of lean mass, 2.0 g/kg lean is 120 g. The lean body mass calculator or the Navy body fat calculator gives you a starting figure.
Does too much protein kick you out of ketosis?
At normal intakes, no. The worry is gluconeogenesis, the liver turning amino acids into glucose. That process is driven by demand, not supply: in a stable isotope study, only about 4 g of the 50 g of glucose produced in the 8 hours after a protein meal came from the protein eaten. Eating 1.2 to 2.0 g/kg will not undo ketosis in a healthy person. Undereating protein to protect ketones costs muscle and gains nothing.
| Level | Per kg body weight | Per kg lean mass | Example, 70 kg at 25% body fat |
|---|---|---|---|
| Lower | 1.2 g | 1.5 g | 84 g by weight, 79 g by lean mass |
| Default | 1.6 g | 2.0 g | 112 g by weight, 105 g by lean mass |
| Higher | 2.0 g | 2.5 g | 140 g by weight, 131 g by lean mass |
Keto for weight loss: what the calorie number means
Keto does not suspend energy balance. In a tightly controlled metabolic ward study, 17 men moved from a high carbohydrate diet to a ketogenic diet at the same calories. Energy expenditure rose by a small amount, about 57 kcal a day measured in a metabolic chamber, and the ketogenic phase did not speed up body fat loss.
Over the long term, a meta analysis of 13 randomised trials with at least 12 months of follow up found people on a very low carbohydrate ketogenic diet lost on average 0.9 kg more than people on a low fat diet. That is a real but small difference. Where keto helps many people is appetite: fewer cravings and a simpler set of food rules make a deficit easier to sustain.
So the calorie target still matters. Use the deficit setting the same way you would on any diet: 15 to 20% is a sensible default, 25% is aggressive and best kept short. The calorie deficit calculator shows how fast a given deficit should move the scale.
Expect a quick drop of 1 to 3 kg in the first week. Each gram of stored glycogen holds about three grams of water, and that water leaves as glycogen falls. It is not fat, and it comes back if you eat carbs again.
Common keto macro mistakes
Treating fat as a minimum. Fat is the remainder, not a target you have to hit. If you are under on fat but on target for protein and carbs while losing weight, that is fine.
Cutting protein to stay in ketosis. Normal protein intakes do not stop ketosis, and too little protein in a deficit costs muscle.
Counting total carbs from a US label without subtracting fibre, or subtracting fibre twice on an EU label. Know which label you are reading.
Ignoring hidden carbs. Sauces, dressings, processed meats, milk and nuts add up quickly when the whole day is 25 g.
Using a fixed 70/20/10 percentage split. It hands a 1,400 kcal dieter and a 3,000 kcal athlete different gram amounts of carbs. Fix carbs and protein in grams instead.
Judging progress on the first week. The early drop is mostly water and glycogen. Judge fat loss from the trend over three to four weeks.
Who should check with a doctor first
A ketogenic diet is a meaningful change, and some people need medical supervision before starting one. That includes anyone with type 1 diabetes, anyone on insulin or SGLT2 inhibitor medication (a known risk of ketoacidosis), anyone on blood pressure medication, people with kidney or liver disease, and women who are pregnant or breastfeeding.
Many people notice headaches, fatigue or cramps in the first week, often called keto flu. Much of it comes from losing water and sodium as insulin drops; extra salt and fluids usually help.
How coaches use a keto calculator
For a coach, the value of a keto macro calculator is that it sets the two numbers a client can actually control, net carbs and protein, and leaves fat flexible. That makes the plan easier to follow than a fixed percentage split, which falls apart the moment calories change.
A practical routine: set net carbs at 20 to 25 g for the first month, protein from lean mass if you have a body fat estimate, and review progress every two weeks. If the client is losing steadily and feels well, leave it. If they want more food variety, add carbs in 5 g steps and watch whether energy and appetite change.
Scraler tracks each client's calorie and macro targets next to what they log, so the numbers from this calculator become a plan you can check. See nutrition coaching for how targets connect to logged meals.
Frequently asked questions
- Is this keto macro calculator free?
- Yes. It is free, needs no signup or email, and shows the full calculation so you can check every number.
- How many carbs can I eat on keto?
- Most definitions put a ketogenic diet at 20 to 50 g of carbohydrate a day. Start at 20 to 25 g of net carbs and raise it slowly if you want to find your personal limit.
- What are good macros for keto?
- Net carbs at 20 to 50 g, protein at about 1.2 to 2.0 g per kg of body weight, and fat filling the rest of your calorie target. For most people that lands around 65 to 80% fat, 15 to 30% protein and 5 to 10% carbs.
- What is the standard keto macro ratio?
- Roughly 70 to 80% fat, 15 to 20% protein and 5 to 10% carbs. Treat it as a typical result rather than a rule, because the percentages shift with your calorie target.
- Will too much protein kick me out of ketosis?
- Not at normal intakes. Gluconeogenesis is driven by your body's glucose needs, and studies show dietary protein contributes only a small share of the glucose produced after a meal. Intakes of 1.2 to 2.0 g/kg are compatible with ketosis.
- Should I count net carbs or total carbs on keto?
- Net carbs, which is total carbohydrate minus fibre. On US labels subtract the fibre yourself; on EU and UK labels the carbohydrate figure already excludes fibre.
- How long does it take to get into ketosis?
- Usually two to four days of eating under about 50 g of carbs, as liver glycogen runs out. Full adaptation, where exercise and energy feel normal again, often takes several weeks.
- Do I need to hit my fat target on keto?
- No. Fat is the flexible macro. Hit your net carb cap and your protein target; eating less fat than calculated simply makes your deficit bigger.
- Can I build muscle on keto?
- Yes, with enough protein, a small calorie surplus and progressive training. Strength performance in high intensity work can dip at first while you adapt.
Sources
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990The BMR equation used for the calorie target.
- FAO/WHO/UNU. Human energy requirements. Report of a Joint Expert Consultation, 2004Background for scaling resting energy expenditure by physical activity level.
- Feinman RD et al. Dietary carbohydrate restriction as the first approach in diabetes management: critical review and evidence base. Nutrition, 2015Defines a very low carbohydrate ketogenic diet as 20 to 50 g of carbohydrate a day, under 10% of energy.
- Jäger R et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr, 2017Source of the 1.4 to 2.0 g/kg protein range for active people.
- Morton RW et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. Br J Sports Med, 2018Source of the 1.6 g/kg point where extra protein stopped adding muscle.
- Fromentin C et al. Dietary proteins contribute little to glucose production, even under optimal gluconeogenic conditions in healthy humans. Diabetes, 2013Source for the small share of post meal glucose that comes from dietary protein.
- Hall KD et al. Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. Am J Clin Nutr, 2016Metabolic ward study: small rise in energy expenditure, no faster body fat loss at equal calories.
- Bueno NB et al. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr, 2013Source of the 0.9 kg long term weight loss difference.
- Gershuni VM, Yan SL, Medici V. Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome. Curr Nutr Rep, 2018Review of nutritional ketosis, its blood ketone range and its effects on weight and metabolic markers.
- Kossoff EH et al. Optimal clinical management of children receiving dietary therapies for epilepsy: Updated recommendations of the International Ketogenic Diet Study Group. Epilepsia Open, 2018Source for the classic 4:1 ketogenic ratio used in epilepsy treatment.
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