Tools
Carb Loading Calculator
Enter your body weight and expected finish time. You get grams of carbohydrate per day for the load and for race morning.
Carbohydrate per day
560 to 840 g
8 to 12 g per kg, each of the 2 days before (36 to 48 hours)
Race morning
70 to 140 g
1 to 2 g per kg, 2 to 3 hours before the start
Your plan
- 2 days out: 560 to 840 g of carbohydrate across the day.
- Day before: 560 to 840 g of carbohydrate across the day. Spread it over meals and snacks, and choose lower-fibre, familiar foods.
- Race morning: 70 to 140 g of easily digested carbohydrate, 2 to 3 hours before the start. Nothing you have not eaten before a long session.
Expect the scales to go up 1 to 3 kg after loading. That is stored glycogen and the water that comes with it.
Rehearse the plan before a long training session first. Read the full guide: carb loading for marathon and Ironman.
How the numbers work
| Finish time | Carbohydrate | When |
|---|---|---|
| Under 60 min | 5 to 7 g/kg | 24 hours before |
| 60 to 90 min | 7 to 9 g/kg | 24 hours before |
| Over 90 min | 8 to 12 g/kg per day | 36 to 48 hours before |
| Race morning | 1 to 2 g/kg | 2 to 3 hours before the start |
These ranges come from our guides to carb loading for marathon and Ironman and carb loading for HYROX. For club sprint and Olympic racing, see the night-before plan. Once the load is done, plan what you take during the race with the Fueling Strategy Engine.
Frequently asked questions
How many grams of carbs should I eat when carb loading?
For races over 90 minutes, most guidance sits at 8 to 12 g of carbohydrate per kg of body weight per day for the 36 to 48 hours before. A 70 kg athlete lands between 560 and 840 g a day.
Do I need to carb load for a 10K or a sprint triathlon?
Not a full load. For races under an hour, a normal carbohydrate-rich day before (about 5 to 7 g per kg) and a familiar breakfast are enough.
How long before a race should I start?
For long events, 36 to 48 hours before the start. For races of 60 to 90 minutes, the 24 hours before is enough at about 7 to 9 g per kg.
What should I eat on race morning?
1 to 2 g of carbohydrate per kg of body weight, 2 to 3 hours before the start, from low-fibre foods you have eaten before long sessions.
Why does my weight go up after carb loading?
Stored glycogen holds water, so a gain of 1 to 3 kg after a full load is normal.
Add this calculator to your club website
Free for clubs, coaches and event organisers. Paste this code into any web page. It stays up to date automatically.
<iframe src="https://hydrax.com.au/embed/carb-loading-calculator" title="Carb loading calculator" width="100%" height="640" style="border:0;max-width:720px" loading="lazy"></iframe> <p><a href="https://hydrax.com.au/tools/carb-loading-calculator">Carb loading calculator</a> by HYDRAX</p>
Disclaimer: This page is general information for healthy adult athletes and is not medical, dietetic or coaching advice. Individual carbohydrate, fluid and sodium requirements vary with body weight, sweat rate, conditions and health status. Speak with your doctor, sports physician or an accredited sports dietitian before changing your nutrition or supplement routine, rehearse any fuelling plan in training before race day, and always follow the directions and warnings on the product label.