About this calculator
The Carb Loading Calculator estimates daily carbohydrate targets for endurance athletes using body-weight-based grams per kilogram ranges.
Carb loading is most useful for endurance events lasting longer than about 90 minutes. Diabetes, gastrointestinal disorders, eating disorders, and medical nutrition therapy require individualized advice.
Uses common endurance carb-loading ranges: approximately 10–12 g/kg/day for 36–48 hours before events longer than 90 minutes, with a moderate 8–10 g/kg/day option.
Activated — sports nutrition estimate
Educational estimate only; not a diagnosis, prescription, or treatment plan.
Formula and method
Daily carbohydrate target = body weight in kg × selected g/kg/day range. Classic loading option: 10–12 g/kg/day. Moderate option: 8–10 g/kg/day. Total loading carbohydrate = daily target × loading days.
Limitations and when not to rely on this result
- Educational estimate only; not a diagnosis, prescription, or treatment plan.
- Result depends on accurate inputs and may not apply to complex medical situations.
- Use clinician judgment, local guidance, and urgent care pathways when symptoms are severe.
Frequently asked questions
Who should carb load? +
Carb loading is mainly used for endurance events longer than about 90 minutes, such as marathons, long cycling events, or triathlons.
How many grams of carbs per day? +
Common protocols use about 10–12 g/kg/day for 36–48 hours. Some athletes use a more moderate 8–10 g/kg/day range.
Should I carb load for a 5K? +
Usually no. Shorter events often do not require formal carb loading, though normal fueling still matters.
What if I have diabetes? +
Do not use high-carbohydrate loading without individualized diabetes guidance and glucose-monitoring plans.
Can carb loading upset my stomach? +
Yes. Practice the strategy before race week and choose familiar foods that you tolerate well.