How Many Gels Per Hour Do You Actually Need? A Marathon Fueling Plan by Finishing Time

Here's the part nobody says out loud: the right number of gels depends on how long you are out there. A 2:50 marathoner and a 4:45 marathoner are not running the same race, are not burning fuel at the same rate, and definitely should not be following the same gel schedule.

The single number that matters: carbs per hour

Forget gels for a second. The actual currency of marathon fueling is carbohydrates per hour (g/hr):

• 30–60 g/hr — the safe range for most runners with an untrained gut
• 60–90 g/hr — the performance range, requires gut training and a 2:1 glucose-to-fructose mix
• 90–120 g/hr — the elite/heavily trained gut range, almost always with hydrogel-style fuels

A standard gel sits between 22–30 g of carbohydrate. Maurten 100 is 25 g. SiS Beta Fuel is 40 g. A Gu Original is 22 g. "One gel every 30 minutes" might put you at 44 g/hr or 80 g/hr depending on the brand — which is why it's a sloppy answer.

Why slower marathoners need more total carbs

Most beginner-targeted articles tell first-timers to take fewer gels because "you're running slower and burning less." This is half right and entirely misleading.

Yes, a 4:30 marathoner burns slightly fewer carbs per minute than a 3:00 marathoner. But the 4:30 marathoner is on the course 90 extra minutes. Even at a lower per-hour intake, that's more total carbs — and the slower runner spends those extra 90 minutes deeper into glycogen depletion, where every incoming gram matters more.

The plan, by finishing time

Targets assume a moderately gut-trained runner, road marathon, normal weather, 60–80 kg body weight.

Sub-3:00

• Per-hour target: 70–90 g/hr
• Total carbs: 210–270 g
• Gel math (25 g gel): 8–11 gels
• Schedule: First gel at 25 minutes, then every 20–25 minutes

3:00–3:30

• Per-hour target: 60–80 g/hr
• Total carbs: 200–270 g
• Gel math: 8–11 gels
• Schedule: First gel at 30 minutes, then every 25–30 minutes

3:30–4:00

• Per-hour target: 50–70 g/hr
• Total carbs: 200–280 g
• Gel math: 8–11 gels
• Schedule: First gel at 30–35 minutes, then every 30 minutes

4:00–4:30

• Per-hour target: 45–65 g/hr
• Total carbs: 200–290 g
• Gel math: 9–12 gels
• Schedule: First gel at 35–40 minutes, then every 30 minutes. Add a sports drink between gels for variety.

4:30+

• Per-hour target: 40–60 g/hr
• Total carbs: 200–300 g
• Gel math: 9–13 gels (or equivalent)
• Schedule: First gel at 40–45 minutes, then every 30 minutes. Plan for at least one solid food option around mile 18–20.

The summary you can screenshot

| Finishing time | g carbs/hr | Total carbs | First gel | Frequency | |---|---|---|---|---| | Sub-3:00 | 70–90 | 210–270 | 25 min | 20–25 min | | 3:00–3:30 | 60–80 | 200–270 | 30 min | 25–30 min | | 3:30–4:00 | 50–70 | 200–280 | 30–35 min | 30 min | | 4:00–4:30 | 45–65 | 200–290 | 35–40 min | 30 min | | 4:30+ | 40–60 | 200–300 | 40–45 min | 30 min |

Practising the plan

You will not magically tolerate 70 g/hr on race day if you've only ever taken two gels on a long run. Three rules:

1. Practise on your three longest runs before race day. Hit your race-day per-hour target on each one.
2. Practise with the exact products you will use. Brand, flavour, caffeine status.
3. Practise taking gels at race pace. A gel at easy pace and a gel at marathon pace go down differently — blood is being diverted away from your gut at race effort.

How to scale the plan to you

• Under 60 kg: Drop 10 g/hr from each band.
• Over 80 kg: Add 10 g/hr.
• Hot day (over 22°C): Drop 5–10 g/hr — gut absorbs less when blood is shunted to skin for cooling.
• You normally cramp: It's almost certainly a sodium and gut-training problem. Add 300–500 mg of sodium per hour first.

How Sweatr does this

Sweatr builds your per-hour carb target from your body weight, recent training load, projected finishing time, sweat rate, and the weather forecast for your race. It then maps that target to actual products in your fuel kit so you know exactly what to carry, when to take it, and how much sodium to pair it with.

Download Sweatr free on the App Store and let your watch data do the math. It takes about three minutes to build your first plan.

The number on the gel packet is not your plan. The number on the gel packet, multiplied by your gut tolerance, divided by your finishing time, adjusted for your sweat rate is your plan.