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Gel calculator

How many gels to buy and carry for your race, split between the bike and the run, from your carb target, the size of your gel and the sports drink you will drink.

h:mm, for example 2:45

h:mm, for example 1:55

g/h

Suggested 90 g/h for this time. Leave empty to use it, or type your own.

g

Most gels hold 20 to 25 g. Check the label.

g

Check the label or your mix. Often 30 to 80 g.

Full bottles of that drink.

Gels to buy

16

8 for the bike, 6 for the run, plus one spare for each. On the bike carry them taped to the top tube, in a bento box or in your tri suit pockets. On the run use the suit pockets or a small gel belt.

Carb target, bike
90 g/h
Carb target, run
60 g/h
Carbs from gels, bike
176 g
Carbs from gels, run
132 g
Gels for the bike
8
Gels for the run
6
Spare gels
2
How it works

How the gel count is worked out

For each leg the calculator multiplies your carb target in grams per hour by the hours on that leg. It then takes off the carbs you will get from your bottles of sports drink and from aid stations, divides what is left by the carbs in one gel and rounds up. One spare gel per leg covers a dropped gel or a rough patch.

The target is prefilled from the same ladder as the triathlon nutrition calculator, so the two pages agree. On a long race the run gets 20 to 30 g an hour less than the bike, because many athletes tolerate less while running. That split is our estimate. You can overwrite the number if you have trained a different amount.

Where to carry them

On the bike, tape gels to the top tube, use a bento box behind the stem, or put them in the pockets of your tri suit. Take the first one 15 to 20 minutes in and set a watch reminder for the rest. For the run, keep two or three in the suit pockets or a small gel belt and take the rest from aid stations.

Gels are easy to forget in the rush of the morning, so add them to your triathlon packing list. To check the fluid and sodium side of your plan, measure your sweat rate.

Sources

  • Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 2014.
  • Burke LM, Hawley JA, Wong SHS, Jeukendrup AE. Carbohydrates for training and competition. Journal of Sports Sciences, 2011;29(Suppl 1):S17-S27.
  • The run versus bike split, one spare gel per leg, the 22 g default gel and the gel counts in the answers below are our own arithmetic and estimates.
Questions

How many gels do I need for a Half distance triathlon?

At 60 to 90 g of carbs per hour over a bike of about three hours and a run of about two, with a 22 g gel and no other fuel, that is roughly 8 to 12 gels on the bike and 4 to 7 on the run, as a rough estimate. Sports drink and aid stations bring that number down.

How many gels do I need for a Full distance triathlon?

On a bike of about six hours at 70 to 90 g an hour, you need 19 to 25 gels worth of carbs for the bike alone if you carry no drink. Most athletes cover a large part with sports drink and carry gels for the rest. Enter your own times above for the exact count.

How many carbs are in a gel?

Most gels hold 20 to 25 g of carbs, and some high-carb gels hold 40 g or more. The label on the packet is the number to use. Put it in the calculator instead of the default.

Should I take gels on the swim?

No. You cannot carry or take anything in the water, so fuel up with a normal breakfast 1 to 4 hours before the start and take your first gel 15 to 20 minutes into the bike.

Do I take gels with water?

Yes. Many athletes take a gel with a few sips of water rather than sports drink, because the drink adds carbs on top of the gel and can be too concentrated for the stomach. Concentrated carbs without enough fluid can slow emptying, so test it in training.

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