Keto Calculator: Your Keto Macros
A ketogenic diet keeps carbs under about 50 g a day. Enter your details to see your calories and how much fat, protein and net carbs to eat each day.
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- Updated 16 October 2026
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Fill in your details and your answer appears here as you type.
How we got it
Calories come from Mifflin-St Jeor resting energy times your activity level; to lose weight we take about 500 off, never below a safe floor. Net carbs (total carbohydrate minus fibre) are set to your choice between 20 and 50 g, the range Alberta Health Services gives for a ketogenic diet. Protein is the middle of our protein range for your body; fat fills the rest at 9 calories a gram (protein and carbs give 4).
Updated . Sources: Mifflin, St Jeor and others, 1990, American Journal of Clinical Nutrition.
The evidence
Every recommendation on this page links here. The badge shows what kind of source it is, so you can judge how strong it is.
- Guideline
Defines ketogenic diets as high in fat and very low in carbohydrate, under 50 g a day (20 to 50 g, counted as net carbohydrate: total minus fibre). Recommends medical monitoring on a ketogenic diet, and warns that people with diabetes risk low blood sugar if their medicines are not adjusted.
Alberta Health Services, Nutrition Guideline, May 2019 (reformatted September 2025): Restricted Carbohydrate in Chronic Disease Management
- Observational study
The resting energy equation used here, built from measurements in 498 adults.
Mifflin et al., 1990, American Journal of Clinical Nutrition: A new predictive equation for resting energy expenditure in healthy individuals
- Review
Higher-protein diets of 1.2 to 1.6 g per kg a day, with about 25 to 30 g a meal, helped appetite, weight control and keeping lean mass while losing weight. Longer studies were mixed, mostly because people found the diet hard to stick to.
Leidy et al., 2015, American Journal of Clinical Nutrition: The role of protein in weight loss and maintenance
- Trial
In 609 adults, a healthy low-fat and a healthy low-carb diet lost about the same weight over 12 months (5.3 vs 6.0 kg, not a significant difference).
Gardner et al., 2018, JAMA (DIETFITS): Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial
- Review
In 32 controlled feeding studies swapping carbs for fat at the same calories, lower-fat diets burned slightly more (26 calories a day) and lost slightly more fat (16 g a day): tiny differences, so calories matter far more than the carb to fat split.
Hall and Guo, 2017, Gastroenterology (meta-analysis of feeding studies): Obesity Energetics: Body Weight Regulation and the Effects of Diet Composition
Our own rules of thumb
These are our choices, not findings from a study. We list them so you know which parts are judgement calls.
- The three carb levels (20, 30 and 50 g of net carbs) are our presets within the guideline's 20 to 50 g.
- To lose weight we take about 500 calories off, never below your resting energy or 1,200 (women) / 1,500 (men) calories.
- Protein uses the middle of our protein range; fat fills the rest of your calories.
Questions
How many carbs can I eat on keto?
Ketogenic diets keep net carbs under about 50 g a day, often 20 to 50 g. Net carbs are total carbohydrate minus fibre.
Is keto better than other diets for weight loss?
Not by much, on the evidence. In a year-long trial of 609 adults, a healthy low-carb diet and a healthy low-fat diet lost about the same weight, and feeding studies find calories matter far more than the carb to fat split. Pick the way of eating you can keep.
Is keto safe?
Guidelines recommend medical monitoring on a ketogenic diet. If you take medicine for diabetes, talk to your doctor before cutting carbs this far: blood sugar can drop too low if the dose is not adjusted.
What are net carbs?
Total carbohydrate minus fibre: the carbohydrate your body digests and absorbs. Keto targets count net carbs.
How much fat should I eat on keto?
Whatever fills the rest of your calories once protein and carbs are set: often 60 to 75% of calories. The calculator works it out in grams for you.
Turn this number into a plan
The free bodymaths app keeps your numbers, plans your training and meals around them, and adjusts as you log.
- A dated forecast that updates as you log
- Workouts and meals built around your numbers
- Private: your data stays on your device
Free, no card.