Nutrition
Race Day Fuelling Calculator
Plan your carb, fluid and sodium intake for race day based on duration, body weight and expected sweat rate.
Carbs per hour
80 g
Fluid per hour
650 ml
Sodium per litre
600 mg
Total carbs
280 g
Total fluid
2.3 L
Total sodium
1365 mg
Hour-by-hour plan
| Hour | Carbs | Fluid |
|---|---|---|
| 1 | 80 g | 650 ml |
| 2 | 80 g | 650 ml |
| 3 | 80 g | 650 ml |
| 4 | 40 g | 325 ml |
Practical mix: a 30 g gel every 20–25 minutes, plus sports drink to top up carbs and fluid. Always rehearse race-day fuelling in long training runs.
Enter your race duration, body weight and conditions. We compute a target carb intake per hour (following current sports-science guidance of 60–120 g/h for endurance events), a fluid target and a sodium target — plus a simple hour-by-hour plan you can rehearse in training.
FAQ
How much carbohydrate can I actually absorb?
Most trained runners tolerate 60–90 g/h using a mix of glucose and fructose. Elite marathon and ultra athletes push this to 100–120 g/h, but it requires deliberate gut training over several weeks.
Do I need to fuel for a 5K or 10K?
No. For efforts under about 75 minutes, your muscle glycogen is sufficient. Focus on being well-fuelled going in rather than fuelling during.
What about sodium?
As a starting point, aim for 300–700 mg of sodium per litre of fluid, higher in the heat or if you are a salty sweater. Rehearse in training.
KYN
Want this automated?
KYN computes your zones, paces and load — and uses them to build training that adapts every week.
Build your planOther calculators