Carb Loading Calculator
Work out how many grams of carbohydrate to eat per day when carb-loading before an endurance race, scaled to your body weight.
How it works
Daily carbs (g) = body weight (kg) × g per kg per day · Carb calories = grams × 4 kcal
Carbohydrate loading tops up muscle and liver glycogen before long events (roughly 90+ minutes) so you can hold pace before hitting the wall. Research supports about 8–12 g of carbohydrate per kilogram of body weight per day for one to three days, alongside reduced training. It is a fuelling strategy, not a licence to overeat fat and protein.
Worked example
A 70 kg runner loading at 9 g/kg eats 70 × 9 = 630 g of carbohydrate per day, about 2,520 kcal from carbs. Over a 2-day load that is 1,260 g total — spread across meals and snacks, roughly 158 g each across four meals.
Frequently asked questions
How many days should I carb-load?
Modern protocols are short: 1–3 days of high carbohydrate intake with tapered training is enough to saturate glycogen stores. The old week-long depletion-then-load routine is no longer necessary for most athletes.
Will I gain weight from carb loading?
You may see 1–2 kg on the scale, largely water: each gram of stored glycogen binds about 3 g of water. That water is useful fuel and hydration for the race, not fat gain.
Do I need to load for a 5K or 10K?
No. Loading benefits events long enough to deplete glycogen — typically 90 minutes or more. For short, fast races normal eating is fine.
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A general sports-nutrition guide, not individual dietary advice. Practise fuelling in training, never for the first time on race day.