Quick answer: To calculate keto macros, estimate your basal metabolic rate (BMR), multiply by an activity factor to get total daily energy expenditure (TDEE), adjust calories for your goal, then divide them into fat, protein and net carbohydrates. A common split is about 70% fat, 20% protein and 10% carbs. Treat the result as a starting point and adjust with your provider.
Key takeaways
The calculator starts by estimating your basal metabolic rate from your weight, height, age and sex.
It then adjusts for your activity level and sets calories for weight loss, maintenance or weight gain.
Those calories are split into net carbs, protein and fat, but protein should not be cut too low just to hit a ratio, especially with age.
Step 1: Estimate your BMR
Men: BMR = 88.4 + (13.4 × weight in kg) + (4.8 × height in cm) − (5.68 × age) Women: BMR = 447.6 + (9.25 × weight in kg) + (3.1 × height in cm) − (4.33 × age)
Step 2: Estimate your TDEE
- Sedentary: BMR × 1.2
- Lightly active: BMR × 1.375
- Moderately active: BMR × 1.55
- Very active: BMR × 1.725
- Extremely active: BMR × 1.9
Step 3: Set calories for your goal
For weight loss, aim for a modest deficit below TDEE; for maintenance, eat about your TDEE; and for weight gain, aim for a modest surplus above TDEE.
Step 4: Split into macros
- Net carbs: commonly about 5–10% of calories (see carbohydrate intake)
- Protein: about 20–25% of calories (see protein intake)
- Fat: the remaining calories (see fat intake)
- Net carbs = total carbohydrate minus fiber
What does the research show behind this calculator?
The calculator starts with resting energy, and the most widely used equation comes from a 1990 study by Mifflin and colleagues. They measured resting energy expenditure with indirect calorimetry in 498 healthy adults aged 19 to 78, 247 women and 251 men, about half of normal weight and half with obesity. Weight, height, age, and sex explained 71% of the differences between people, and the older Harris-Benedict equation overestimated measured needs by about 5%. The limitation is that the group was healthy and not very diverse.
A 2005 systematic review by Frankenfield and colleagues compared the four most common equations against measured metabolism. The Mifflin-St Jeor equation was the most reliable, predicting resting energy within 10% of the measured value in more people with and without obesity than the other equations. Still, it was off by more than 10% for some individuals, and older adults and U.S. ethnic minorities were underrepresented, so use the calculator’s number as a starting estimate.
For the diet itself, a 2013 meta-analysis by Bueno and colleagues pooled 13 randomized trials lasting 12 months or longer that compared a very-low-carbohydrate ketogenic diet (no more than 50 g of carbohydrate a day) with a low-fat diet. The ketogenic groups lost on average 0.91 kg more (data from 1,415 people), with lower triglycerides and diastolic blood pressure and higher HDL, but LDL cholesterol rose slightly (0.12 mmol/L). The difference in weight was small, which suggests that sticking with an eating pattern matters at least as much as its macro ratio.
A note on these numbers
These ranges are general education, not a prescription; your needs depend on your health, medications and goals, so personalize them with your provider. Equations are estimates and can be off for many people.
Healthy aging lens
Getting enough protein matters more with age to protect muscle, so don’t cut protein too low to hit a ratio.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have diabetes or take insulin, sulfonylureas or SGLT2 inhibitors (risk of low blood sugar or ketoacidosis), or if you take blood pressure medication or diuretics. The same is true if you have kidney, liver, gallbladder or pancreas disease, or high cholesterol, if you are pregnant, breastfeeding, or have a history of disordered eating, or if you want a keto plan tailored to your labs and goals.
See a medical provider promptly for nausea and vomiting, abdominal pain, confusion, fruity-smelling breath with rapid breathing, or very high blood sugar or ketone readings, which can signal ketoacidosis.
Want a keto plan that’s safe for your health?
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Do these calculated targets look right for my health, or should we adjust them?
How should I calculate my macros for my body and activity level?
Should I adjust my macros as my goals change?
How precisely do I need to track macros for keto to work for me?
Frequently asked questions
How do I calculate keto macros?
Estimate BMR, multiply by activity for TDEE, adjust for your goal, then split into fat, protein and carbs.
What is a typical keto ratio?
About 70% fat, 20% protein and 10% carbs, adjusted to the person.
What are net carbs?
Total carbohydrates minus fiber.
Are calculators accurate?
They’re estimates; track your results and adjust.
Sources
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr 1984. PMID: 6741850. https://pubmed.ncbi.nlm.nih.gov/6741850/
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc 2005. PMID: 15883556. https://pubmed.ncbi.nlm.nih.gov/15883556/
- Bauer J, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc 2013. PMID: 23867520. https://pubmed.ncbi.nlm.nih.gov/23867520/
- MedlinePlus: Carbohydrates
- MedlinePlus: Dietary Proteins
- Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990. PMID: 2305711. https://pubmed.ncbi.nlm.nih.gov/2305711/
- 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 2013. PMID: 23651522. https://pubmed.ncbi.nlm.nih.gov/23651522/
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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