For most runners, the first gel goes in around 30 to 45 minutes into the race. After that, take one every 30 to 45 minutes, so you fuel before fatigue shows up. Your finish time, the carbs per gel, your breakfast and Singapore’s heat all move that schedule a little. The plan below helps you build one you can trust on race morning.
TL;DR
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Take your first gel at about 30 to 45 minutes, before you feel tired, then repeat roughly every 30 to 45 minutes.
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Aim for 30 to 60 g of carbohydrate per hour. Going past about 60 g from glucose-based sources can upset your stomach.
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A 90-minute half marathon usually needs 1 to 2 gels, while a 2-hour finish usually needs 3 to 4 of 25 g each.
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Take gels with water just before an aid station, and practise the whole plan in training, including hot, humid sessions.
Table of Contents
A simple half marathon gel timeline
Think of the race in three blocks.
Before the start. Eat a normal, familiar breakfast. A gel 10 to 15 minutes before the gun is optional. Runner’s guidance on gel timing says to use it only if you have tested it in training and counted it in your total carbohydrate plan.
The first gel. Most guidance lands between 30 and 45 minutes into the race. The idea is to start fuelling before fatigue appears. Some sources suggest waiting longer. RUN Singapore advises the first gel at around 60 to 75 minutes into a run. That suits easier, longer efforts better than a race pace half marathon. If you are running hard for under two hours, the earlier window is the safer starting point.
Repeat gels. From there, take another every 30 to 45 minutes as needed. For a 2-hour half marathon, that usually means gels around the 35, 70 and 105-minute marks. Adjust the spacing to the carbs in your gel.
How much carbohydrate you need per hour
The Australian Institute of Sport recommends 30 to 60 g of carbohydrate per hour for endurance exercise lasting 1 to 2.5 hours. The same page notes that glucose-based intake above about 60 g per hour usually adds no benefit. It can also cause gut discomfort because the intestinal transporters become saturated. A 2022 peer-reviewed review also recommends up to 60 g of rapidly oxidised carbohydrate per hour for sessions up to three hours.
Research on higher intakes keeps moving. A 2026 Journal of Nutrition review suggests the upper limit could rise from 90 to 120 g per hour, at least for trained participants. For a half marathon, you do not need to chase those numbers. The 30 to 60 g range is the right place to build your plan.
Here is the maths with real products. A gel with 22 g of carbs, such as the SiS GO Isotonic Gel, taken every 30 minutes gives you about 44 g per hour. Taken every 40 minutes, it gives you about 33 g per hour. Both sit inside the target range. Check the label of whatever you choose and do the same sum.
How many gels for your finish time
The number depends on how long you are out there. One published chart from Mavr uses 25 g gels and works out to about 35 to 55 g of carbs per hour:
| Expected finish time | Gels needed (25 g each) |
|---|---|
| 1:30 | 2 to 3 |
| 2:00 | 3 to 4 |
| 2:30 to 3:00 | 4 to 6 |
Other sources are a little lower for faster runners. For a race of about 90 minutes, one fuelling guide puts the need at roughly one or two gels. It depends on the gel’s carbohydrate content, your breakfast, your intensity and any other carbohydrate you take. For a runner expecting two hours, Half Marathon Trainer suggests practising a 20 to 25 g gel every 35 to 45 minutes, in line with the ACSM range of 30 to 60 g per hour.
In practice, pick the plan at the lower end of your range first. Add a gel only if your training runs show you fading late.
Taking gels in Singapore’s heat and humidity
A 6 am start at the Padang or along the East Coast is warm and humid before the sun is even up. Your fuelling plan needs to account for that.
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Keep carbs comparable. The 2026 Journal of Nutrition review reports that heat can reduce exogenous carbohydrate oxidation by 20% to 30%. It still says carbohydrate targets should generally stay comparable with cooler races. If your stomach complains, reduce or simplify your intake a little.
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Start hydrated, don’t force fluids. The 2015 heat consensus suggests about 6 ml of fluid per kg of body mass every 2 to 3 hours before exercise in the heat. During the race, aim to limit excessive water loss without gaining weight. Recreational athletes should avoid overdrinking because of the risk of hyponatraemia.
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Test your sodium. Singapore-focused coaching guidance recommends practising regular drinking and fuelling in training and using effort rather than fixed pace in the heat. It also says to test sodium needs rather than guess them on race day.
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Train in race conditions. A Singapore running coach quoted by PrisChew suggests simulating race conditions, including some sessions in the hotter part of the day. Runners who only train in cool early-morning or late-night sessions may not be acclimatised.
The World Athletics energy guide makes a useful point here. Absorption is affected by pace, weather and what your stomach is used to, so no single gel schedule is correct for everyone. For more on this, read our guide to energy gel timing in Singapore’s heat and our BYD Singapore Marathon fuelling guide for half and full distances.
Gels, water and aid stations
A gel is concentrated carbohydrate. It works best when you wash it down properly.
Take gels just before an aid station. The World Athletics guide advises exactly that, so you can follow the gel with water. Check the race map and plan your gels around the water points, not around the clock alone. If your 70-minute mark falls 400 metres before a station, take it at the station.
Use water with standard gels. Take most gels with water unless the label says otherwise, according to this running hydration guide. The same guide warns that combining gels with an isotonic sports drink can cause gut problems. Use water with a standard gel, or use the drink on its own. Some gels are formulated as isotonic and need no water, which makes them handy if a station is far away. If you are deciding when a sports drink makes more sense than plain water, this explanation of when electrolyte drinks beat water is a good companion read. Our comparison of sports drink types covers the options in more detail.
Fuel the brain too. Coach and blogger Amanda Brooks notes in her half marathon fuelling article that some studies show even the sweetness of a sports drink on your tongue can give a performance boost. That is one more reason to tie your intake to aid stations.
How long does a gel take to kick in?
RUN Singapore says most runners feel a gel working within about 15 minutes, depending on how quickly the body absorbs simple sugar into the bloodstream. That is why timing works best when you take the gel before you hit a low. If you wait until your legs feel heavy, you will be running through that dip for the next 15 minutes. To understand why some gels feel faster than others, see our explainers on energy gel absorption and gel ingredients that speed carb uptake.
Avoiding stomach problems
The most common downside of gels is gut discomfort. It is usually a planning issue rather than a gel issue. Based on AIS guidance, you can lower the risk by doing the following:
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Stay at or under about 60 g of glucose-based carbohydrate per hour.
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Practise taking carbohydrate in training, because the gut can be trained.
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Build a plan that fits your hydration needs and your stomach comfort.
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Take gels with water, not on top of a strong sports drink.
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Reduce or simplify your intake if heat-related discomfort starts.
If you have a sensitive stomach, start with our guide to energy gels for a sensitive stomach. Try one gel type at a time in training so you know exactly what works.
Practical tips to lock in your plan
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Rehearse it. Use your long runs and at least one race-pace session to run the exact plan: same gels, same timing, same water.
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Write your schedule down. For example: gel at 35 minutes, 70 minutes and 105 minutes. Set a watch alert for each one so you do not rely on memory when you are tired.
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Do the carb sum. Gel carbs divided by minutes between gels, multiplied by 60, should land between 30 and 60 g per hour.
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Carry what you need. Pack your gels in a belt or shorts pocket. Do not rely on the course for a brand you have never tried.
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Eat the usual breakfast. Nothing new on race day.
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Use effort, not pace. In heat, run to effort so your gut is not stressed by trying to hold a cool-weather pace.
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Track the data. A watch that records pace, heart rate and time helps you spot when you fade and when to adjust timing. Browse the Garmin smart watch collection if you are choosing one for training.
For a wider overview of gel types and when each suits you, see our energy gels guide for running and endurance athletes. If you are building your whole week of fuelling, our coach’s 36 to 48 hour plan for humid races walks through the days before the start.
Our perspective: simple, tested, repeatable
We talk to runners across Singapore every week, and the pattern is consistent. The runners who fuel well are not the ones with the fanciest plan. They are the ones who picked a gel, learned how it sits in the heat, and took it on schedule in training until it became routine.
That is why we focus on authentic products and fast delivery. When you are building a plan, you need the same gel in your hands for several long runs, not a substitute. Next-day delivery within Singapore means you can order a few options, test them on your weekend long runs, and still have time to settle on your race day choice.
For a half marathon, we usually point runners to a small kit: a few gels that carry the carbs you need, a hydration option you tolerate, and a plan you have written down. Start with 30 to 45 minutes for the first gel, test it, and adjust. You are building confidence as much as fuelling, and confidence is what carries you through the last 5 km.
Jason John
Fuel your half marathon with Racepack
We stock energy gels, hydration, recovery powders and more from leading international brands, with guaranteed authenticity and next-day delivery within Singapore. If you want a ready-made starting point, the GU Half Marathon Endurance Fuel Bundle is built around this exact distance. Looking for other flavours and formats? Try the High5 Energy Gel or the Applied Nutrition Isotonic Energy Gel.
After the race, our recovery powders and protein powders help you refuel. You can browse everything on Racepack.sg.
FAQ
When should I take my first energy gel in a half marathon?
Most runners do well with the first gel at about 30 to 45 minutes into the race, before fatigue sets in. Some sources suggest 60 minutes or later for easier efforts. If you are racing hard, the earlier window is the safer start. Always test your timing in training.
How often should I take gels during a half marathon?
A good starting point is one gel every 30 to 45 minutes after the first. The goal is 30 to 60 g of carbohydrate per hour. Check the carbs on your gel label and space them to match.
How many gels do I need for a half marathon?
It depends on your finish time and gel size. With 25 g gels, a 1:30 finish needs about 2 to 3, a 2:00 finish about 3 to 4, and a 2:30 to 3:00 finish about 4 to 6. Faster runners with a good breakfast may do well on 1 to 2.
Should I take a gel before the start?
It is optional. A gel 10 to 15 minutes before the gun can work, but only if you have tested it in training and counted it in your total carbohydrate plan. If you have eaten a normal pre-race meal, you can skip it.
How long does it take for a gel to kick in?
Most runners feel the effect within about 15 minutes of taking a gel. Take it before you feel flat, not after. That way the energy arrives as you need it.
Do I need water with an energy gel?
Most standard gels should be taken with water unless the label says otherwise. Take the gel just before an aid station so you can wash it down. Avoid pairing a standard gel with a strong sports drink, as it can upset your stomach. Isotonic gels are made to be taken without water.
What are the downsides of taking energy gels?
The main issue is stomach discomfort, which is more likely above about 60 g of glucose-based carbohydrate per hour or when you have never practised with gels. Train your gut on long runs, use water, and keep to a plan you have rehearsed. If the heat upsets your stomach, reduce or simplify your intake.
Does Singapore’s heat change when I should take gels?
The timing stays broadly similar and carb targets remain comparable with cooler races. What changes is the practice: train in similar heat, start hydrated, test your sodium needs and run by effort. Reduce your gel intake slightly if you get heat-related stomach issues.
Can I use gels instead of a sports drink?
You can use either, or both at different points, but avoid stacking a standard gel on top of an isotonic drink. Choose a clear plan: gels with water, or a drink on its own. Count the carbs from every source toward your hourly total.
What should I eat after a half marathon?
Once you finish, focus on rehydrating and refuelling with carbohydrate and protein. A recovery powder or protein powder is an easy option when you are not hungry yet. Stay with products you have used before.
Ready to build your race plan? Buy Now at Racepack.sg and get your gels delivered next day within Singapore.
