How many carbs should I eat per hour during a race?

For efforts over 2.5 hours, aim for 60–90 g of carbs per hour, using a glucose–fructose mix so your gut can absorb it. Between 1 and 2.5 hours, 30–60 g/h is enough, and under an hour you usually don't need to fuel at all.

How much water should I drink per hour?

It depends on your sweat rate — typically 400–800 ml/h, more in the heat. The best guide is to weigh yourself before and after a long training run: each kilogram lost is about one litre of fluid you didn't replace. The ‘Estimate my drink’ button gives a starting point from your weight, effort and temperature.

How much sodium do I need?

Sweat contains roughly 300–1000 mg of sodium per litre. For long or hot races, 500–800 mg per litre of drink is a common target; heavy or salty sweaters may need more. This tool multiplies your chosen concentration by the fluid you drink.

Is this fueling planner free?

Yes — free, with no sign-up. Everything is computed in your browser and nothing is sent to a server.

Race fueling & hydration planner

Plan how much to eat and drink during a long race. Set your target duration and your hourly goals for carbs, fluid and sodium — you get the totals to carry and a schedule telling you exactly what to take at each interval. Everything runs in your browser.

Race duration

Body weight (kg)

Temperature (°C)

Effort

Carbs (g/h)Recommended for this duration: ~90 g/h

Fluid (ml/h)

Sodium (mg/L)

Take every (min)

Total carbs180 g720 kcal

Total fluid1.80 L1800 ml

Total sodium1.26 g1260 mg

Roughly8 gels (25 g)4 bottles (500 ml)

Feeding schedule

What to take in each interval to hit your hourly targets. Round up and carry a little extra.

Time	Carbs	Fluid	Sodium
0:00–20:00	20 g	200 ml	140 mg
20:00–40:00	20 g	200 ml	140 mg
40:00–1:00:00	20 g	200 ml	140 mg
1:00:00–1:20:00	20 g	200 ml	140 mg
1:20:00–1:40:00	20 g	200 ml	140 mg
1:40:00–2:00:00	20 g	200 ml	140 mg
2:00:00–2:20:00	20 g	200 ml	140 mg
2:20:00–2:40:00	20 g	200 ml	140 mg
2:40:00–3:00:00	20 g	200 ml	140 mg

Estimates only, based on general sports-nutrition guidelines. Sweat and carb tolerance vary a lot — test your fueling in training, not on race day.

How to plan your race fueling

1
Enter your race duration
Type how long you expect to be out there, as h:mm:ss. Your goal finish time works well.
2
Set your hourly targets
Pick carbs per hour (30–90 g depending on duration), fluid per hour, and the sodium concentration of your drink. Use ‘Estimate my drink’ to size your fluid from your weight, effort and the temperature.
3
Follow the schedule
The planner gives you the totals to carry and how much to take at each interval — copy it onto your race plan or a wristband.

Frequently asked questions

How many carbs should I eat per hour during a race?: For efforts over 2.5 hours, aim for 60–90 g of carbs per hour, using a glucose–fructose mix so your gut can absorb it. Between 1 and 2.5 hours, 30–60 g/h is enough, and under an hour you usually don't need to fuel at all.
How much water should I drink per hour?: It depends on your sweat rate — typically 400–800 ml/h, more in the heat. The best guide is to weigh yourself before and after a long training run: each kilogram lost is about one litre of fluid you didn't replace. The ‘Estimate my drink’ button gives a starting point from your weight, effort and temperature.
How much sodium do I need?: Sweat contains roughly 300–1000 mg of sodium per litre. For long or hot races, 500–800 mg per litre of drink is a common target; heavy or salty sweaters may need more. This tool multiplies your chosen concentration by the fluid you drink.
Is this fueling planner free?: Yes — free, with no sign-up. Everything is computed in your browser and nothing is sent to a server.

Pace calculator → Pace, time or distance — with projected race times.