Free tool
Carb Loading Calculator
For a marathon, many sports dietitians recommend about 10 to 12 grams of carbohydrate per kilogram of body weight per day for the 36 to 48 hours before the race. For a 70 kg runner that is roughly 700 to 840 g a day. Enter your weight below to get your number.
- Grams per day for your weight
- Marathon and half marathon
- Free to use
This is general guidance, not personal medical or dietary advice. If you have diabetes, a medical condition or a history of disordered eating, talk to an accredited sports dietitian first.
How many days before a marathon should I carb load?
Most runners load for the last 36 to 48 hours, so the two days before race day. Old style depletion phases are not needed.
What should I eat when carb loading?
- Rice, pasta, bread, potatoes, oats and cereals
- Fruit juice, sports drinks and lollies to top up without feeling stuffed
- Lower fibre and lower fat choices so your gut stays settled
- Familiar foods only, nothing new before a race
Will carb loading make me gain weight?
You will probably gain 1 to 2 kg, mostly water stored with carbohydrate in your muscles. That is a good sign. It is fuel you will use in the race.
Do I need to carb load for a half marathon?
Usually not a full load. A well fuelled day before and a good breakfast is enough for most half marathon runners.
Read the full 3 day carb loading meal plan on the blog.
Questions runners ask
How many carbs should I eat before a marathon?
About 10 to 12 grams per kilogram of body weight per day for the 36 to 48 hours before the race. For a 70 kg runner that is about 700 to 840 grams a day.
How many days before a marathon should I carb load?
Most runners load for the final 36 to 48 hours before the race.
Do I need to carb load for a half marathon?
Usually not a full load. A well fuelled day before and a good breakfast is enough for most runners.
Will carb loading make me gain weight?
Often 1 to 2 kg, mostly water stored with glycogen. It is fuel for the race and goes once you run.
What should I eat the night before a marathon?
A familiar, carbohydrate rich, lower fibre meal such as rice or pasta with a simple sauce, eaten early enough to digest.
Is carb loading safe for everyone?
It is general guidance. If you have diabetes or another medical condition, check with a doctor or accredited sports dietitian first.
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