Most marathoners need 2–3 standard energy gels per hour, or roughly 60–90 grams of carbohydrate, to sustain race pace.
Figuring out how many energy gels for marathon day comes down to one number: your hourly carbohydrate target. The widely accepted range of 60–90 grams of carbs per hour translates cleanly into gel counts, and the math holds across most popular products — but your individual gut tolerance and race time shift the answer.
The Standard Formula: 60–90 Grams of Carbs per Hour
Sports nutrition guidance from multiple official bodies converges on the same target: 60–90 g of carbohydrate per hour during endurance racing. A standard energy gel delivers roughly 20–25 g of carbs, which means most runners should aim for 2–3 gels per hour, spaced every 20–30 minutes.
The Australian Sports Commission describes gels as a compact carbohydrate source for fueling before, during, and after exercise. It also notes that gels vary in carbohydrate content and that most are concentrated, meaning they should be taken with water rather than on their own.
When to Take Your First Gel
Start early. Reputable marathon fueling plans call for the first gel roughly 20–30 minutes into the race, or just before the start — not when you feel fatigue creeping in.
A common spacing pattern is one gel every 20–30 minutes or roughly every 6 km. Some runners prefer a gel every other water station, which naturally lands in that window for most race courses.
- First gel: 20–30 minutes in, or shortly before the start
- Spacing: every 20–30 minutes or every 6 km
- Water: follow concentrated gels with a few swallows to reduce stomach upset
The Australian Sports Commission explicitly warns that concentrated gels are more likely to cause gut problems if not followed by water. SiS, a major gel manufacturer, likewise advises its own runners to take the first gel after 20 minutes and target 3 gels per hour.
Product Differences Change the Count
Not all gels carry the same carb load, so product choice moves the numbers. Maurten’s official marathon guide offers two in-race options: six Gel 100s at one every 6 km, or four Gel 160s as a lighter-carrying alternative.
The math is straightforward. A 25-gram-carb gel needs roughly 3 per hour to hit the 60–90 g target. A 40-gram-carb gel needs only 2 per hour. Check the label on your chosen product before race day and do the division.
| Gel Type | Carbs per Gel | Gels per Hour (60–90 g Target) |
|---|---|---|
| Standard gel | 20–25 g | 3 per hour |
| Maurten Gel 160 | 40 g | 2 per hour |
| Isotonic gel | ~22 g | 3 per hour |
The best energy gels for race day page breaks down the top performers if you want a tested recommendation.
Common Fueling Mistakes That Cost Runners
The biggest error is introducing an untested gel on race morning. Marathon clinics warn, “Never try anything new on race day.” Your gut reacts differently under race stress, so every gel you plan to use should be practiced at race pace during long training runs.
Skipping water is the second most common mistake. Concentrated gels draw fluid into the stomach, which can trigger cramps or nausea without a few ounces of water to dilute them. Only a small number of “isotonic” gels are formulated to be taken without water.
Starting too late ranks third. Waiting until you feel depleted means playing catch-up for miles. Once glycogen stores empty, getting back on top of fueling is nearly impossible mid-race.
FAQs
Can I train my stomach to handle more gels?
Yes, gut tolerance improves with practice. Start with one gel per hour during long runs and gradually build to your race-day target over several weeks. Sip water with each gel and note any bloating or nausea. Adjust the timing or switch products if your stomach consistently protests.
Do caffeinated gels change the fueling math?
The carbohydrate count stays the same, but caffeine adds another variable. Many runners reserve caffeinated gels for the later miles to combat fatigue, then switch back to plain gels to avoid overstimulation. Test caffeine timing in training to find your personal tolerance.
What if I’m running slower than 5 hours?
Slower finishing times mean more hours on your feet and a higher total gel count. Carry extras or confirm what the race provides on course before relying on aid stations alone.
References & Sources
- Australian Sports Commission. “How and when do I use it?” Explains gel timing and the importance of water for concentrated gels.