And extra tips to fuel for race day success.

Most endurance runners take anywhere from 2 to 4 energy gels for a half marathon. But this number depends on the race duration, pre-race nutrition, gut tolerance, and your estimated finish time.

This article explains how many gels you need for a half marathon to ensure an optimal nutritional strategy for the best race day performance.

What you will learn:

  • How many energy gels you need for a half marathon

  • How to practice your half marathon and energy gel timing before race day

  • Common mistakes to avoid when taking energy gels 

How many gels for a half marathon?

Most runners will need 2-4 energy gels for a half marathon.

According to research, you want 30 to 60g of carbs per hour to fuel your event.

GEL30 contains 30g of carbs so you would need two per hour.

If you are aiming for a 2-hour finishing time, that would be four energy gels.

You would adjust this as needed for your estimated finish time.

How energy gels work

Energy gels contain simple sugars like glucose, fructose, and maltodextrin for quick absorption into the bloodstream.

During exercise, your muscles use glycogen as fuel. Glycogen is stored in the muscles and the liver as energy. The body only has enough glycogen — or energy — to perform 75 to 90 minutes of aerobic exercise before running low on glycogen.

When this happens, you are likely to slow down dramatically and may bonk or hit the wall. This is when you run out of energy and find it very difficult to continue running.

The simple sugars in energy gels help keep the glycogen stores topped up — a little like putting fuel into your car.

Consuming energy gels every 20 to 30 minutes during a half marathon or long run, for example, helps maintain consistent energy levels and can prevent you from bonking.

Additionally, most gels also contain electrolytes and sometimes caffeine, like GEL30 Caffeine, for a little energy boost mid-endurance activity or race.

Electrolytes, like sodium, potassium, and magnesium, help maintain proper muscle function and hydration, which enables you to get the most out of gels.

It’s a good idea to plan a race day hydration strategy too for the best results.

Determining energy gel needs 

Athletes need anywhere from 30 to 60g of carbohydrates/hour for endurance activity lasting 90 minutes or longer.

A typical energy gel, like GEL30, contains 30g of carbohydrates. You can also get energy gels that contain more carbohydrate, like GEL50, which has 50g of carbs.

To determine your energy gel needs, take an estimate of your finish time and how many gels this equates to.

For example, if you plan to run a 2-hour half marathon, you would need 3 energy gels. You may even experiment with 4 gels.

You want to test your fueling strategy during your weekly long training run. This will allow you to avoid possible GI upset on race day and allows you to fine-tune your strategy to fuel you to the finish line (for example, you might want to add or remove an energy gel).

Sample gel fueling strategy

Below is a sample fueling strategy for a 2-hour half marathon:

  • 0:00 race start 

  • 0:40 energy gel 1 (30g of carbs)

  • 01:20 energy gel 2 (30g of carbs)

  • 01:50 energy gel 3 (30g of carbs)

You may have an electrolyte drink 1 to 2 hours before as well. 

Common mistakes with energy gels 

Many athletes make several mistakes when they first start using energy gels. 

1. Taking too many gels

If you can take one energy gel and it gives you extra energy, why not take two, or better yet, four or six?

Unfortunately, there is such a thing as taking too many gels at one time.

Your body only absorbs so much sugar per hour (approximately 60 to 90g according to research). 

Taking too many gels can cause stomach upset and is more likely to negatively impact your performance.

More is not better when it comes to energy gels. Strategic timing is a much better approach.

2. Not trying energy gels in training 

If you wait until race day to try energy gels, you’ve left it too late.

You do not want to try energy gels for the first time on race day. Why? Because you don’t know how your body and stomach will respond.

For whatever reason, you may have a negative reaction to energy gels, causing stomach upset. 

The last thing you want when chasing a half marathon personal best is a trip to the bathroom.

Try energy gels during your training, preferably during your weekly long distance run by using gels every 20 to 30 minutes.

3. Taking energy gels without water

Energy gels are concentrated and need water to be properly digested.

If you do not take energy gels with water, this can cause stomach upset, GI issues, and slow absorption.

Every time you take an energy gel, take a few sips of water to wash it down.

Also, don’t use sports or carbohydrate drinks to wash down energy gels. These also contain simple sugars and may cause slow digestion or stomach upset.

You can use carb-rich drinks between energy gels, but ideally, not at the same time. Stick to water.

4. Taking their first energy gel too late

If you take your first energy gel once you’re already fatigued or after hitting the wall, it’s too late.

Afer your glycogen stores are depleted, it’s difficult to bounce back.

Take your first energy gel 20 to 40 minutes into your half marathon. 

Use an energy gel at similar intervals throughout. Again, practice your fueling strategy during training.

You may find that you can take more energy gels at regular intervals. 

5. Ignoring caffeine content 

Caffeine gels can improve performance and reduce your perception of fatigue. They can also improve focus.

Although you don’t want to take too many caffeinated gels. This can cause stomach upset and jitters.

GEL30 Caffeine contains 150mg of caffeine. If you were to take 3 energy gels during a half marathon, that would be 450mg of caffeine.

Save the caffeine gels for when you’ll need them most — a steep hill or 20 to 30 minutes before the final stretch. 

6. Starting a half marathon with low fuel 

Most endurance runners think you don’t need to carb-load before a half marathon.

And while it’s not quite as necessary as a full marathon, increasing your carb intake 1 to 3 days before race day ensures your glycogen stores are full.

Carrying energy gels during a race 

You can carry energy gels in your pockets on race day.

Alternatively, you can wear a hydration vest or running belt for the extra storage.

Alternatives to energy gels

Some people do not tolerate energy gels too well. 

If that’s you, you might want to experiment with energy bars like BAR50 or carbohydrate drink mixes like MIX+.

If you prefer whole food options, you can try sweets, bananas, or dried fruit.

Read the best energy gel alternatives for optimal performance for more options.

Recovery nutrition 

Energy gels are used for quick, mid-run fuel. They’re high in glucose and fructose and low in protein. They do not give the body what it needs most after a race.

Get plenty of carbohydrates and protein to improve recovery after a half marathon.

You also want to drink plenty of fluids and electrolytes to properly rehydrate. It will also help with recovery.

Key takeaways

  • Most runners take 2 to 4 energy gels during a half marathon

  • Aim for 30 to 60g of carbs per hour to fuel performance

  • One energy gel typically contains around 30g of carbs 

  • There is no number set in stone, so play around with it and find what works best for you

  • Practice taking energy gels on a weekly long run to get used to them