What this tool does
Given daily calories and a style, the tool assigns a carbohydrate percentage and converts it to grams at 4 kcal/g. Low is a smaller slice, endurance a larger one. It does not put you in ketosis and does not periodize race week by itself.
How it works
Low ≈ 25%, moderate ≈ 40%, high ≈ 55%, endurance ≈ 60% of calories. Those are planning buckets, not ISSN law. Athletes in heavy mileage often need more carbohydrate per kilogram than a percentage on a small calorie budget can deliver — in that case raise calories or accept that the “endurance” percent is still food-limited.
Formula and methodology
Carbohydrate g = calories × style% / 4. Style% is 0.25 / 0.40 / 0.55 / 0.60. ACSM/Academy performance nutrition discusses higher carb availability for prolonged or high-intensity work; this page is a calorie-share shortcut, not grams per kg of body weight.
How to interpret the result
If you squat and sprint, very low carb is a preference, not a requirement. If you have a long run, shifting toward high or endurance for that day is more honest than a 25% split named after a forum. Protein should already be fixed in grams.
Example
At 2,400 kcal, moderate (40%) is 240 g carbohydrate. Endurance (60%) is 360 g. Low (25%) is 150 g. A 70 kg runner at 360 g is about 5 g/kg — useful for longer sessions, still not a championship taper plan.
Common mistakes
- Choosing “low” during a high-mileage block because fat loss sounded adjacent.
- Forgetting that sauces, fruit, and milk count.
- Cutting carbs and protein together.
- Expecting 60% carbs to feel good on 1,400 kcal — the grams will still be small.
When this estimate may be off
- You need a medical carbohydrate prescription (diabetes education, ketogenic therapy).
- Training volume changed this week and the style was not updated.
- Most “carbs” are sugar-free labeled products with polyols.
- The calorie input is a guess.