Keto Macros Calculator

How to use this keto macros calculator

1. Enter your weight, height, age and sex. Switch between US and metric units at any time; your entries convert, so nothing changes.
2. Add your body fat percentage if you know it. A smart scale, a DEXA scan or calipers will do. Without it, the calculator estimates your lean mass from height and weight.
3. Pick your activity level and goal. Most people start on "Steady", a 20% calorie deficit. If you are unsure about activity, choose one level lower than you think.
4. Set net carbs and protein. 20 g net carbs with moderate protein is the standard starting point.
5. Tick anything in the health check that applies to you. If something does, the result tells you what to discuss with your doctor before you start. Then copy the result, share a link that reopens your numbers, or download the PDF.

Why this keto calculator is different

Most keto calculators sit at the top of a sales funnel. Some hide the result behind an email or a login; others are a single percentage split applied to everyone. This one is built the way a clinician would want it built:

• A health check before the numbers. Insulin, sulfonylureas, SGLT2 inhibitors, blood pressure drugs, kidney disease and pregnancy all change whether keto is safe. Tick one and you get a specific, sourced caution, not a generic disclaimer.
• Protein from your lean mass. A fixed 20 or 25% of calories gives a large person too much protein and a small person too little. Here protein follows the muscle you are trying to keep, and you do not need to know your body fat to get it.
• A safe calorie floor. If a deficit would take you under 1,500 kcal (men) or 1,200 kcal (women), the target is raised to that floor and the tool tells you why.
• What the numbers mean on a food label. You get a fiber target and the total-carb figure it implies, plus per-meal amounts and electrolyte targets for your age and sex.
• Every formula on the page. The math and the sources are below, the tool is reviewed by a named physician, and you can embed it on your own site for free.

How the keto macros are calculated

The calculator works in five steps. Each one uses a published equation or guideline.

1. Lean body mass

If you enter body fat, lean mass is weight × (1 − body fat %). If you leave it blank, the tool uses the Boer equation, the same estimate behind our lean body mass calculator:

• Men: LBM (kg) = 0.407 × weight (kg) + 0.267 × height (cm) − 19.2
• Women: LBM (kg) = 0.252 × weight (kg) + 0.473 × height (cm) − 48.3

2. Resting metabolic rate and TDEE

With body fat entered, BMR comes from Katch-McArdle (370 + 21.6 × LBM in kg), which is built on lean mass. Without it, the tool uses Mifflin-St Jeor (10 × kg + 6.25 × cm − 5 × age + 5 for men, − 161 instead of + 5 for women). BMR is then multiplied by an activity factor from 1.2 (sedentary) to 1.9 (hard training plus a physical job) to give your total daily energy expenditure. Our TDEE calculator shows all three formulas side by side if you want to compare them.

3. Calorie goal

The goal is a percentage of TDEE: −25%, −20%, −10%, 0% or +10%. Any target below the safe minimum (1,500 kcal for men, 1,200 kcal for women) is raised to that minimum and flagged.

4. Net carbs, protein and fat

• Net carbs are a fixed cap: 20, 30 or 50 g a day. A very-low-carbohydrate ketogenic diet is usually defined as 20 to 50 g of carbohydrate a day.
• Protein is 0.6, 0.8 or 1.0 g per pound of lean mass (1.3, 1.8 or 2.2 g per kg).
• Fat fills whatever calories are left: fat (g) = (calories − 4 × protein − 4 × net carbs) ÷ 9.

Fat is the lever on keto, not a target you must hit. In a deficit, eating less fat than the number shown is fine; your body fat makes up the difference.

5. Fiber and electrolytes

Fiber is set at 14 g per 1,000 calories, the Dietary Guidelines figure. Because net carbs are total carbs minus fiber, the label total you will actually see is net carbs plus fiber. Potassium and magnesium are the standard adult targets for your age and sex. Sodium follows keto-adaptation guidance of 3,000 to 5,000 mg a day, because the kidneys excrete more sodium when insulin falls. That loss is the main cause of "keto flu" headaches and fatigue, and an electrolyte powder or a cup of salted broth usually settles it.

Worked examples

A 30-year-old man, 180 lb, 5'10", moderately active

Without a body fat reading, his lean mass is estimated at about 135.6 lb and his maintenance level at 2,763 kcal. A 20% deficit gives 2,210 kcal a day: 20 g net carbs, 108 g protein and 189 g fat. His fiber target is 31 g, so labels will add up to roughly 51 g of total carbs. Hitting 31 g of fiber on keto is harder than it sounds, which is why many people add a fiber supplement.

A 58-year-old woman, 128 lb, 5'1", sedentary

Her maintenance level is 1,318 kcal. The "Fast" goal would put her at 989 kcal, so the tool raises it to 1,200 kcal and says so. Even the gentle 10% deficit works out to 1,186 kcal, which also hits the floor. At 1,200 kcal she gets 70 g protein and 93 g fat. For someone her size, more daily movement does more than a deeper cut: moving her up one activity level raises maintenance enough that the "Slow" goal sits comfortably above the floor.

A 35-year-old lifter, 90 kg, 183 cm, 22% body fat, maintaining

Because he entered body fat, the tool uses Katch-McArdle: BMR 1,886 kcal and maintenance 3,254 kcal at a very active level. On the high protein setting with 30 g net carbs he gets 155 g protein and 279 g fat. That fat figure looks large, but it is what fuels his training at 3,254 kcal without the carbs.

Who should talk to a doctor before starting keto

Most healthy adults can try a ketogenic diet safely. A few groups should not start one on their own, and these are the boxes in the health check:

• Anyone on insulin or a sulfonylurea. The ADA's nutrition consensus notes that very-low-carb eating lowers blood sugar quickly, so doses usually need to come down at the start to avoid hypoglycemia. Frequent checks with a glucose meter are part of doing it safely.
• Anyone on an SGLT2 inhibitor (empagliflozin, dapagliflozin, canagliflozin, ertugliflozin). These drugs carry an FDA warning for ketoacidosis that can occur with near-normal blood sugar, and carbohydrate restriction is a recognized trigger.
• People with type 1 diabetes, kidney disease, a history of kidney stones, or an eating disorder, and anyone pregnant or breastfeeding.
• People with pancreatitis, liver failure or an inherited fat-metabolism disorder, for whom a ketogenic diet is contraindicated.
• People on blood pressure medication or diuretics. Pressure often falls in the first weeks, which can stack with the drug. Keep an eye on it with a home blood pressure monitor.

Frequently asked questions

How do I calculate my keto macros?

Find your daily calories (BMR times an activity factor, minus a deficit if you want to lose weight), cap net carbs at 20 to 50 g, set protein by your lean mass, and let fat fill the remaining calories. The calculator above does all of it and shows the math.

What is the difference between net carbs and total carbs?

Net carbs are total carbohydrates minus fiber (and, on some labels, minus sugar alcohols such as erythritol). Fiber is not digested into glucose, so it barely affects ketosis. Keto targets are almost always given as net carbs, which is why the calculator also shows the total-carb number you will see once your fiber target is met.

How much protein should I eat on keto?

Enough to keep your muscle, which for most people is about 0.8 g per pound of lean mass. The worry that protein "kicks you out of ketosis" is overstated at these amounts. Eating too little is the more common mistake, especially in a deficit and after 65. Our protein intake calculator goes deeper on age and training.

Is keto safe for everyone?

No. It is generally safe for healthy adults, but it needs medical input if you take insulin, a sulfonylurea or an SGLT2 inhibitor, have kidney disease or kidney stones, are pregnant or breastfeeding, or have a history of pancreatitis, liver failure or an eating disorder. The health check in the calculator covers each of these.

Why did my LDL cholesterol go up on keto?

A rise in LDL is common on a high-fat diet, especially one heavy in saturated fat, and in lean people it can be large. It is worth a lipid panel before you start and two to three months in. You can estimate LDL from a standard panel with our LDL calculator, and swapping some butter and fatty meat for olive oil, nuts and fish often brings it back down.

Can I embed this calculator on my site?

Yes. Copy the snippet at the bottom of this page. Dietitians, coaches and clinics can embed it free, with the attribution link included. There is no fee and no signup.

Related tools

• TDEE Calculator: three BMR formulas side by side, with a calorie table for every goal.
• Protein Intake Calculator: a goal-specific, age-aware protein target with a per-meal breakdown.
• Lean Body Mass Calculator: the lean-mass estimate this tool uses, three ways.
• LDL Calculator: check your LDL from a standard lipid panel before and during keto.
• Weight Loss Percentage Calculator: track progress as a share of your starting weight.
• Browse all free tools by Dr. Taylor

Dr. Taylor's recommendations for starting keto

Each links to a full review with current top picks:

• Best Electrolyte Powders: the quickest fix for keto flu in the first two weeks. Choose a sugar-free one.
• Best Fiber Supplements: closes the fiber gap that causes most keto constipation.
• Best Bathroom Scales: a weekly average tells you whether these calorie numbers are right for you.

Sources and methodology

• Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51(2):241–247.
• Boer P. Estimated lean body mass as an index for normalization of body fluid volumes in humans. Am J Physiol 1984;247:F632–F636.
• Katch FI, McArdle WD. Nutrition, Weight Control, and Exercise. Lean-mass BMR equation.
• Feinman RD, et al. Dietary carbohydrate restriction as the first approach in diabetes management. Nutrition 2015;31(1):1–13. Defines the 20 to 50 g/day ketogenic range.
• Evert AB, et al. Nutrition Therapy for Adults With Diabetes or Prediabetes: A Consensus Report. Diabetes Care 2019;42(5):731–754. Medication reduction and hydration when starting a very-low-carb plan.
• Blau JE, et al. Ketoacidosis associated with SGLT2 inhibitor treatment. Diabetes Metab Res Rev 2017. Includes the FDA label warning.
• Masood W, et al. Ketogenic Diet. StatPearls, NCBI Bookshelf. Contraindications and adverse effects.
• Dietary Guidelines for Americans 2020–2025: 14 g fiber per 1,000 kcal.
• National Academies. Dietary Reference Intakes for Sodium and Potassium (2019); NIH Office of Dietary Supplements, Magnesium fact sheet.
• Volek JS, Phinney SD. The Art and Science of Low Carbohydrate Living (2011). Sodium guidance during keto-adaptation.

Reviewed annually against the ADA Standards of Care and the current Dietary Reference Intakes. About Dr. Taylor · Last reviewed October 13, 2026.

Embed this tool on your site

Free for dietitians, coaches, clinics and health educators. The attribution link is part of the snippet. No fee, no signup, no tracking attached to the embed.

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