Many runners have experienced the feeling of “hitting the wall” in a half marathon, even though their fitness is actually in place. This is often related to the energy plan not being optimally planned, or the intake of gels and fluids not being matched to race time and intensity.
Here you get a concrete guide to how many gels you may typically need, and how you can plan their use as part of your energy and hydration strategy – whether you are aiming for 1:25 or 2:15.
How many gels make sense for a half marathon
The key factor is not only the number of gels, but how many carbohydrates you get per hour. For runs lasting 1–2.5 hours, sports nutrition recommendations typically point to around 30–60 g of carbohydrate per hour, depending on intensity and individual tolerance. A standard energy gel often contains around 25–30 g of carbohydrate.
As a rule of thumb for a half marathon, you can use the following as a starting point:
- Under 75 minutes: 0–1 gel, if you have eaten a solid meal 2–3 hours before the start
- 75–105 minutes: 1–2 gels, where you often start early (around 20–45 minutes in)
- Over 105 minutes: 2–3 gels, spread evenly every 20–30 minutes, if it suits your stomach and your pace
Most recreational runners will therefore typically end up with around 1–3 gels for a half marathon, depending on pace and how much carbohydrate also comes from, for example, sports drink along the way.
If you want to plan based on specific products, you can start with PurePower’s range of energy gels for half marathons, which are developed for endurance sports and designed to be practical to use during activity.
How to calculate your gel needs
Instead of guessing, you can make a simple calculation and get a better overview of your energy plan, so you can better support a stable energy intake along the way.
Start by setting a realistic carbohydrate target per hour:
- Easy or moderate pace or sensitive stomach: around 30 g of carbohydrate per hour
- High intensity and trained stomach: up to around 60 g of carbohydrate per hour
Then multiply by your expected race time. Example: You expect to run in 1:50 (1.8 hours) and aim for 40 g of carbohydrate per hour:
- 1.8 × 40 g ≈ 72 g of carbohydrate in total
The next step is to translate that into gels and any sports drink. If one gel contains around 30 g of carbohydrate, this means:
- 72 g corresponds to 2–3 gels (60–90 g of carbohydrate in total), depending on what you also get from drink and other intake
- If, for example, you get 20–30 g of carbohydrate from Carbo Race energy powder in your drinking bottle, in some cases you can reduce the number of gels and still stay close to your planned target
This allows you to adjust according to your setup:
- More gels if you mainly drink water
- Fewer gels if you supplement with carbohydrate-containing sports drink
Examples of gel plans by finish time
Below you will find examples you can use as a starting point. Adjust according to your own experience, tolerance, and race pace. All examples assume that you have eaten a good meal 2–3 hours before the start.
Plan for a half marathon under 75 minutes
For the fastest runners, a half marathon is often an effort of just over an hour at high intensity. Here, the plan is often simple:
- Typical need: 0–1 gel
- No gel if you are used to running hard for 60–70 minutes without extra carbohydrate along the way
- Or 1 gel around 15–25 minutes before the start or 20–30 minutes into the race, if that works well for you
Here, the focus can be on a solid pre-race meal and appropriate fluid intake, rather than unnecessarily increasing the amount of gels.
Plan for a half marathon between 75 and 105 minutes
For many ambitious recreational runners, the finish time falls here, and there can be an advantage to taking a more structured approach to energy along the way.
- Typical need: 1–2 gels
- Gel 1 around 20–40 minutes into the race
- Gel 2 (optional) around 60–75 minutes, depending on how you feel and what you have already taken in via drink
If carbohydrate-containing sports drink is served on the course, in some cases 1 gel combined with drink may be sufficient, depending on the amount per serving and your individual tolerance.
Plan for a half marathon over 105 minutes
The longer you are out on the course, the more important a stable energy plan can be. Here, 2–3 gels can be a relevant guideline for many.
- Typical need: 2–3 gels
- Example for around 2 hours of running:
- Gel 1 at 20–30 minutes
- Gel 2 at 50–70 minutes
- Gel 3 at 80–100 minutes, if you are on the course for over 2 hours
If you often experience a clear drop in energy after 15–16 km, it can typically be related to a long time having passed since your last carbohydrate intake, or your total intake along the way having been low in relation to your needs.
If you are unsure, you can bring an extra gel as a backup. It can be practical to have a reserve if you need extra carbohydrate along the way.
Timing your first gel
A classic challenge is waiting to take the first gel until you clearly feel your energy level dropping. For some, an earlier and more planned approach can be easier to execute.
A more proactive and controlled strategy typically looks like this:
- First gel after around 15–40 minutes, depending on your expected finish time and intensity
- Then one gel every 20–30 minutes as smaller, steady carbohydrate doses, if it suits your plan
An example for a runner around 1:45 in the half marathon could be:
- No gel before the start, but a solid breakfast
- Gel around 30 minutes into the race
- Gel around 65–70 minutes
If you are unsure about flavor or consistency, you can, for example, try a sample pack of gels on your training runs so you can find the variants you feel best with during activity.
How to protect your stomach when using gels
Gels are a concentrated source of carbohydrate, and absorption can be individual, especially at high intensity. With gradual adaptation, you can typically reduce the risk of stomach discomfort.
- Train your stomach by using the same types of gels and the same timing on your long training runs as you will use on race day
- Combine gel with a little water, especially if you often experience discomfort or a “lump” in your stomach
- Avoid very large doses at once and keep around 20–30 minutes between each energy gel
- Stick to products and flavors you have tested before, and avoid experimenting on race day itself
If you know that you have a sensitive stomach, you can deliberately stay at the low end of carbohydrate intake, around 30 g per hour. Here you can supplement with fluids and electrolytes for running and hot days, which are typically used in connection with fluid intake and may be relevant for fluid balance depending on sweat loss.
Caffeine and electrolytes in your energy plan
In addition to classic energy gels, many runners choose to use caffeine and electrolytes as part of their half marathon strategy. How people react is individual, and it is recommended to test it in training beforehand.
Caffeine during a half marathon
For some, caffeine can contribute to a feeling of increased alertness and focus during endurance activity, especially toward the end of a race. The effect and tolerance vary from person to person.
- Use no more than 1–2 caffeinated gels in a half marathon, if you tolerate caffeine
- Place them in the last part of the race, for example at 12–16 km
- Always test caffeine on training runs, so you know how you react
You can combine regular gels with a single caffeine gel in the second half, if you have good experience with it in training.
Electrolytes and fluid balance
Electrolytes are about fluid balance and salt rather than carbohydrate. They can be relevant in warm conditions and with high sweat loss, and many use them in connection with longer training sessions.
- Use electrolytes in your drinking bottle if you want to support a planned intake of fluid and salt
- Separate energy and fluids, so you get carbohydrate from gels and electrolytes via the drink, if it suits your strategy
- Consider tablets or effervescent tablets, which are easy to dose and bring along
One example is Hydro Tabs, which can be mixed in your bottle. If you would like to read more about how much may be relevant for you, you can dive into the blog post can you get too many electrolytes?
If you want a complete setup with both energy and electrolytes for training and racing, you can take a closer look at a complete energy and electrolyte pack where you can plan both gels and drink in one system.
Practical shopping list for your half marathon
To bring it all together, here is a simple checklist you can use when planning your race and packing your bag.
- For races of 75–105 minutes: 2 gels, where 1–2 are used and 1 serves as a backup
- For races of 105–135+ minutes: 3–4 gels, where 2–3 are used and 1 is a backup
- Optionally 1 pack of Carbo Race energy powder for a bottle or belt, if you want part of your energy as a drink
- Optionally electrolyte tablets, if you expect warm conditions or sweat a lot
Test your setup on at least 2–3 long runs leading up to your half marathon. With a tested energy and hydration plan, you can more easily stick to your strategy on race day and adjust as needed along the way. You can also explore PurePower’s sports nutrition for running if you want to build a complete setup for training and race day.