Carb Intake Calculator for Runners & Cyclists

Energy & Fuelling

Carbohydrate Calculator

Your muscles only store enough glycogen for around 90 minutes of hard exercise. Once sessions get long or intense, taking on carbohydrate during exercise maintains blood glucose and delays fatigue, under-fuelling is one of the most common reasons for fading late in a race (Jeukendrup, 2014).

How much you need scales with how long you're out there and how hard you're working, from around 30g per hour for shorter efforts up to 90g per hour for long, intense events using mixed carb sources.

Select the options below to get a personalised estimate of how many carbs to take on per hour and across your whole session.

Duration

90 minutes.

I've trained my gut for high carb intake (regularly fuel 60g+/hr in training)

Intensity

Your fuelling target

Per hour

—

Carbohydrate

Per hour

—

Energy from carbs

Whole session

—

Carbohydrate, total

Whole session

—

Energy, total

Estimate · practise your fuelling in training, never on race day

Based on general ranges from Jeukendrup, 2014, Sports Medicine and the ACSM/AND/DC Position Stand (Thomas et al., 2016). Individual tolerance varies, intakes above 60g/hr rely on mixed glucose + fructose carb sources and a gut that's been trained to handle them.

5 Tips for Fuelling Right

Start fuelling early, before you feel you need it. Glycogen runs down silently, by the time you feel empty it's too late to catch up. For sessions over an hour, take your first carbs within the first 20 to 30 minutes and keep going from there.
Jeukendrup, 2014, Sports Medicine
Little and often beats big hits. Small, regular doses every 15 to 20 minutes keep blood glucose steady and are far kinder on the stomach than one large feed each hour, it's why Pocket Rockets come in four separate chunks.
Burke et al., 2011, Journal of Sports Sciences
Go beyond 60g/hr only with mixed carb sources. The gut's glucose transporters saturate at roughly 60g per hour, combining glucose with fructose uses a second absorption pathway, letting you take on up to 90g per hour and perform measurably better in long events.
Currell & Jeukendrup, 2008, Medicine & Science in Sports & Exercise
Train your gut like you train your legs. Tolerance to in-exercise carbs is trainable, regularly practising your race-day fuelling in training reduces gut discomfort and increases how much carbohydrate you can absorb and use.
Jeukendrup, 2017, Sports Medicine
Don't forget the hours around the session. In-exercise fuelling works best on top of well-stocked glycogen stores, a carb-rich meal 1 to 4 hours beforehand, and carbs soon after finishing, set up both today's session and tomorrow's.
Thomas et al., 2016, Medicine & Science in Sports & Exercise