Carb loading means increasing carbohydrate intake while tapering or resting to build up glycogen, the fuel stored in your muscles. It is mainly used before endurance events lasting around 90 minutes or longer, such as a marathon.

Common guidance focuses on the 36–48 hours before the race, alongside lighter training or rest. One large pasta dinner the night before is not the same as a planned carb load.

General endurance guidance suggests around 10–12g of carbohydrate per kilogram of body weight per day during the loading window. This is not a personal prescription: your needs and tolerance vary, and a sports dietitian can help you choose a suitable target.

Choose familiar carbohydrate-rich foods such as bread, rice, pasta and bananas. Juice or sports drinks can also contribute. Practise your approach in training so you know which foods and portions you tolerate, rather than trying new foods just before race day.

No. Carb loading builds your stored fuel before the race. You still need a practised plan for breakfast and for food, drinks or gels during the event.

carbs. is a free marathon carb-loading planner. It uses your weight and race date to build a loading schedule, then helps you find meal ideas, make a shopping list and track carbs from food and drinks.

carbs. is free to use. You don’t need an account or a subscription: set up your plan and start logging in your browser.

No. carbs. is a planning and tracking tool, not a substitute for a qualified nutritionist, registered dietitian or medical advice. Its targets and food estimates are general guidance. For advice tailored to your health, training or dietary needs, speak to a qualified professional.

carbs. multiplies your body weight by your selected grams of carbohydrate per kilogram to calculate a daily target. Your race date sets the loading schedule. You can review the suggested rate and choose a two- or three-day load when you set up your plan.

Carb amounts are estimates. Brands, preparation and portion sizes vary, so check your packaging and edit the amounts before logging. Meal ideas include the listed ingredients and any suggested drink; log other extras separately.

Meal ideas prioritise ingredients on your shopping list when you have one. Without a list, carbs. still shows suggestions for the time of day. Portions stay editable, and you can choose Show me more to see other ideas.

Yes. After race day, choose Plan another race to create your next plan. Your previous plan, diary, shopping list and notes remain available in Progress. Use the race selector to look back at a completed carb load.

Your plan and diary are saved in this browser, on this device. They don’t automatically sync elsewhere, and clearing browser data removes them. Export a backup from Profile to keep a copy.

Yes. Export a backup from Profile, transfer the file to your other device and import it into carbs. The backup includes your current and previous races, diary, saved products, shopping lists and notes. Import replaces the app data in the receiving browser, so export a copy of that data first.