Keto Macro Calculator

Ketogenic macros without the mysticism: energy from Mifflin-St Jeor, carbs capped, protein evidence-based, fat fills the rest.

  • Nutrition
  • 3 cited sources
  • Runs in your browser
Sex

Evidence-based range 1.6 to 2.2 g/kg (Morton 2018).

Daily keto macros

2,168 kcal

Net carbs
25 g
Protein
144 g
Fat (remaining energy)
166 g

Estimates for planning, not prescriptions, anyone on glucose-lowering medication should involve their clinician before carbohydrate restriction.

Methodology

The calculator is honest arithmetic on top of published pieces, with no keto-specific magic:

  1. Energy: resting metabolic rate from the Mifflin-St Jeor equation, multiplied by the standard activity factor, then adjusted for your goal (−20% to lose, +10% to gain), the same engine as the TDEE calculator.
  2. Carbohydrate: fixed in grams at your chosen cap. Ketogenic diets are conventionally defined by restricting to roughly 20 to 50 g of net carbs per day; the default sits at 25 g.
  3. Protein: body weight × your chosen g/kg from the evidence-based 1.6 to 2.2 range (Morton et al. 2018), ketosis does not change protein requirements.
  4. Fat: every kilocalorie left after carbs and protein, at 9 kcal/g. Fat is the adjustable energy lever of the diet, not a target with independent meaning.

Interpreting your result

The ISSN's review of diet types is worth internalising: across approaches from low-fat to ketogenic, body-composition outcomes are similar when calories and protein are matched. Choose keto because the food pattern suits your adherence, hunger and preferences, the deficit does the fat loss, whichever diet delivers it.

Expect a rapid early weight drop from glycogen and water (often 1 to 2 kg) that isn't fat loss; judge progress from the trend after the first fortnight.

Limitations

  • Anyone on insulin or other glucose-lowering medication must involve their clinician before restricting carbohydrate, doses that were right before can become dangerous.
  • The energy estimate inherits Mifflin-St Jeor's individual error (±10% is common); adjust from real-world results after 3 to 4 weeks.
  • Net carbs (total minus fibre) is the convention this tool uses, label reading varies by country, since UK/EU labels already exclude fibre from "carbohydrate".

Sources

Pull the receipts, 3 cited sources

FitTools · sources

  1. 01 Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51:241-247
  2. 02 Aragon AA, Schoenfeld BJ, et al. International Society of Sports Nutrition position stand: diets and body composition. J Int Soc Sports Nutr 2017;14:16
  3. 03 Morton RW, et al. Protein supplementation meta-analysis, the 1.6 to 2.2 g/kg range. Br J Sports Med 2018;52:376-384

Every formula cited ✓

Frequently asked questions

How many carbs on a keto diet?
Ketogenic diets are conventionally defined by restricting carbohydrate to roughly 20 to 50 g of net carbs per day, low enough that most people shift towards fat and ketone metabolism. This calculator lets you set the cap anywhere in that range.
How is protein set on keto?
The same way as on any diet: from body weight using the evidence-based range of about 1.6 to 2.2 g/kg for people who train. Very-low-protein versions of keto are unnecessary for ketosis and cost you muscle.
Why does fat get whatever calories remain?
Because carbs are fixed in grams and protein is set by body weight, fat is the adjustable energy lever, it fills the gap between those two and your calorie target. That's the arithmetic of the diet, not a claim that fat is magic.
Is keto better for fat loss?
The ISSN's review of diet types concludes that widely different approaches, low-fat through ketogenic, produce similar body-composition results when calories and protein are matched. Choose it for adherence and preference, not metabolic magic.
What are net carbs?
Total carbohydrate minus fibre. Fibre isn't absorbed as glucose, so keto carb caps are usually counted as net carbs, that's the number this calculator asks for.

Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.

Last reviewed:

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