Race Nutrition Calculator

Most people bonk because they guessed. Answer five questions and get carbs, sodium, and fluid per hour for your race — then the gels and bottles that actually add up to it.

What distance are you racing?
How hard are you racing it?

This sets your estimated finish time — and how much your gut can handle while you do it.

How much do you weigh?
How much do you sweat?

Think about a hard two-hour session, not a recovery jog.

What's the forecast for race day?
Do you use caffeine?

How these numbers are worked out

Carbs scale with the day, not your body

Carbohydrate targets are absolute, not per kilo: a 60kg and a 90kg athlete racing the same 70.3 both want roughly 80g an hour. A sprint barely needs fuelling at all — you're finished before your stores are.

Sodium is about you, not the distance

Sweat rates vary by a factor of three between athletes, and salt concentration by more. That's why a heavy, salty sweater in the heat lands near 1,400mg an hour while a light sweater on a cool day needs a third of it.

Everything lands on the bike

You can't eat in the water and you can barely eat while running hard. The bike is a moving dinner table — finish it fuelled and hydrated and the run is a completely different race.

Caffeine is a back-half tool

Roughly 3mg per kilo helps, and it helps most when perceived effort is already brutal. Taken at the swim start it's mostly gone by the time you need it — and it can make an anxious stomach worse.

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