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Keto macros & carbs

Keto Calculator

This calculator sets daily net carbs, protein, and fat grams for nutritional ketosis using Mifflin-St Jeor total daily energy expenditure (TDEE) and lean body mass (LBM) for protein. It fixes net carbs by rigor level, targets protein from LBM times your slider, and fills remaining calories with fat. It does not measure blood ketones or replace advice from a registered dietitian.

By Jeff Beem

Updated

Ketogenic macro model, educational; runs locally.

01

Profile & rigor

Drives protein from lean mass.

0.80
0.60.81.2
0%
02

Macros

Daily target about 2,426 kilocalories modeled. Fat 206 grams, 76 percent of calories. Protein 113 grams, 19 percent. Net carbohydrates 30 grams, 5 percent.

Baseline

BMR 1,765
TDEE 2,426
LBM 140.8 lb
BF% 20 (assumed)

Electrolytes (rough targets)

3000–5000
Na mg
3500–4700
K mg
300–500
Mg mg

Transition tips

Early ketosis adaptation varies, hydration and electrolytes help many people.

  • Adequate sodium with clinician-aware targets
  • Bone broth or mineral-rich fluids if they fit your plan
  • Magnesium (often discussed in 300–500 mg/day ranges, ask your provider)
  • Drink to thirst

How to read this

Prioritize 113g protein. Use fat for satiety, you may not need the full 206g daily. Keep net carbs under 30g for the rigor you selected.

Reading your keto macro targets

Section 02 is the readout: daily kcal, macro grams, BMR/TDEE/LBM baseline, electrolytes, and the How to read this note. Prioritize the protein line; fat is the calorie lever you may not need to eat in full.

Example: male 5′10″, 176 lb, moderate rigor

Widget defaults → section 02 shows about 2,408 kcal modeled, 113 g protein, 204 g fat, 30 g net carbs. Baseline tile: BMR 1,749, TDEE 2,405, LBM 141.1 lb (assumed 20% body fat). Inputs: male, age 30, Light activity, 0.8 g/lb protein slider, 0% deficit.

Protein slider and the dark panel

Moving Protein (g / lb LBM) rebalance fat automatically because carbs stay at the rigor cap. Undershooting protein during a deficit risks lean loss; raising the slider within range does not widen the carb ceiling.

Deficit slider and fat grams

The deficit control cuts fat grams only. The amber kcal line under the slider shows how far target intake sits below TDEE when deficit is above zero.

Electrolytes card and transition tips

Section 02 always shows the same sodium, potassium, and magnesium ranges on the amber electrolytes card; they do not scale with weight. The dismissible green Transition tips card in the widget is general education during early adaptation, not a prescription.

Keto calculator: net carbs, protein, and fat from TDEE

Sets daily net carbs, protein, and fat using Mifflin-St Jeor TDEE and lean body mass (LBM) for protein. Does not measure ketones or replace medical nutrition therapy.

What this calculator does

Builds a ketogenic macro plan in grams, not fixed 70/25/5 percentages. Computes BMR and TDEE, applies an optional calorie deficit, fixes net carbs by rigor button, sets protein from LBM × slider, and assigns remaining calories to fat. Section 02 adds BMR, TDEE, LBM, static electrolyte ranges, and a reading note. No food logging, ketone testing, or clinical diet orders.
  • Net carbs (guardrail):
    Fixed daily cap from rigor: 20 g, 30 g, or 50 g, plus optional athletic bonus.
  • Protein (goal):
    Protein (g)=LBM (lb)×slider (g/lb)\text{Protein (g)} = \text{LBM (lb)} \times \text{slider (g/lb)}
  • Fat (lever):
    Fat (g)=Target kcal−4×Protein g−4×Net carb g9\text{Fat (g)} = \frac{\text{Target kcal} - 4\times\text{Protein g} - 4\times\text{Net carb g}}{9}

How the math works

Mifflin-St Jeor BMR from weight, height, age, and sex; TDEE = BMR × activity factor (default Light × 1.375). Target kcal = TDEE × (1 − deficit%). With default male profile (176 lb, 5 ft 10 in, age 30), BMR rounds to 1,749 kcal and TDEE to 2,405 kcal. Assumed 20% body fat → LBM 141.1 lb; at 0.8 g/lb protein = 113 g (452 kcal). Moderate rigor fixes net carbs at 30 g (120 kcal). Remaining energy is 2,405 − 452 − 120 = 1,833 kcal → fat 1833 ÷ 9 ≈ 204 g (macro sum rounds to 2,408 kcal on the panel).
A 20% deficit targets 1,924 kcal while protein and carbs stay pinned, cutting fat to about 150 g. Rigor buttons only change the carb cap; Rigorous also disables athletic bonus. Bonus adds 1 g net carbs per 50 kcal exercise on Moderate or Relaxed. The How to read this note reminds you fat is a satiety lever, not a quota.

Limits of the model

TDEE and body-fat estimates vary by individual. Net carb labels on food may not match your glucose response. Electrolyte ranges are static, not personalized. Medical ketogenic diets for epilepsy or metabolic disorders require clinician supervision. Adult planning and education only.

Keto Calculator FAQ

How many net carbs does this calculator set for ketosis?

Section 01 rigor buttons set the daily net carb cap before fat fills remaining calories. Rigorous = 20 g, Moderate (default) = 30 g, Relaxed = 50 g. Optional Athletic carb bonus adds 1 g per 50 kcal exercise entered. The widget does not measure blood ketones.

How is protein calculated on this page?

Protein (g) = lean body mass (LBM) in pounds × the Protein (g / lb LBM) slider (default 0.8, range 0.6–1.2). LBM uses weight and body fat % from section 01, or assumed 20% (male) / 25% (female) when blank. At defaults, LBM is about 141 lb and protein is 113 g.

What happens when I move the calorie deficit slider?

Deficit lowers target calories from TDEE; net carbs and protein grams stay fixed and fat drops. At default TDEE 2,405 kcal, a 20% deficit targets 1,924 kcal and cuts fat from 204 g to 150 g (protein 113 g, net carbs 30 g unchanged). See the example card for the zero-deficit baseline.

What is the difference between Rigorous, Moderate, and Relaxed?

Only the net carb ceiling changes; TDEE and protein math stay the same. Rigorous locks 20 g and disables athletic bonus. Moderate is the default 30 g cap. Relaxed allows 50 g and keeps athletic bonus available.

What is the athletic carb bonus checkbox?

On Moderate or Relaxed, each 50 kcal of daily exercise adds 1 g net carbs. Example: 300 kcal exercise on the default 30 g cap → 36 g total. The helper line under the exercise field updates live.

How does body fat percentage affect my macros?

Body fat % sets LBM, which drives protein only. Tap Estimate for a BMI-and-age-based fill, or enter DEXA, caliper, or Navy-method readings for tighter targets. TDEE still comes from Mifflin-St Jeor plus activity, not from body fat % alone.

What do the electrolyte numbers on the results panel mean?

Static planning ranges on the amber card: sodium 3,000–5,000 mg, potassium 3,500–4,700 mg, magnesium 300–500 mg. They do not scale with weight. The dismissible green Transition tips card is general education, not a prescription.

Will extra protein on the slider kick me out of ketosis?

This widget does not model gluconeogenesis or ketones. It holds net carbs at your rigor cap while protein can rise to 1.2 g/lb LBM. For medical ketogenic protocols, follow clinician gram targets instead of the default 0.8 slider.

Sources & citations

References used for the calculation method and definitions. Links open in a new tab when available.

[1]
Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247

Source for the Mifflin-St Jeor basal metabolic rate equation used for TDEE in this widget.

[2]
Jäger R et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20

Protein intake context for active adults; informs the 0.6–1.2 g/lb LBM slider range.

[3]
Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids - National Academies

Macronutrient energy values (4 kcal/g protein and carbohydrate, 9 kcal/g fat) used in calorie partitioning.

Fitness Reference Note

Informational Use: These calculations (BMI, Calories, etc.) are based on standard statistical formulas and are intended for general reference and goal-setting purposes only.

Consult Experts: This tool does not provide medical advice, diagnosis, or treatment. Results may not be accurate for athletes, pregnant individuals, or those with underlying health conditions.

Health Safety: Always consult with a healthcare professional or qualified trainer before beginning any new diet or intensive exercise program.

Privacy First: All calculations are performed locally in your browser. No health data is stored or transmitted to any server.

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