Quick answer: most runners need 7–14 energy gels to properly fuel a marathon — based on 60–90g of carbohydrate per hour and a typical 22–25g gel. That's far more than the 3–4 gels many first-timers carry, and it's exactly why so many runners hit the wall at mile 20. Here are the real numbers by finish time — and why, once you see them, you might not want to fuel your race on gels at all.
How Many Gels You Need, by Finish Time
Sports science is clear: for efforts over 90 minutes you should be taking in 60–90g of carbohydrate per hour (higher intakes are possible with a glucose-fructose blend). A standard energy gel contains 22–25g of carbs. Do the maths:
| Finish time | Total carbs needed (60–90g/hr) | Gels required (25g each) | FTP Pastilles equivalent |
|---|---|---|---|
| 3:00 | 180–270g | 7–11 gels | 12–18 pastilles |
| 3:30 | 210–315g | 8–13 gels | 14–21 pastilles |
| 4:00 | 240–360g | 10–14 gels | 16–24 pastilles |
| 4:30 | 270–405g | 11–16 gels | 18–27 pastilles |
| 5:00 | 300–450g | 12–18 gels | 20–30 pastilles |
Start fuelling around 20–30 minutes in, then keep intake steady — roughly every 20–30 minutes — rather than waiting until you feel empty. By the time you feel the bonk coming, it's already too late to fix it.
The Problem With Carrying 12 Gels
Look at that table again and a practical problem appears: a 4:30 marathoner fuelling properly needs to carry, open, and stomach a dozen or more gels. That's where gel-based fuelling starts to break down:
- Gut distress: the concentrated, syrupy texture sits heavily, and most gels need water to absorb properly — miss a water station and cramps follow.
- Flavour fatigue: by mile 20, choking down another gloopy sachet can turn your stomach. Runners routinely skip doses they need simply because they're dreading the next gel.
- Waste and cost: every gel is a single-use wrapper, and per gram of carbohydrate, gels are among the most expensive ways to fuel.
The Alternative: Hitting the Same Numbers With Chews
Solid chews deliver the same carbohydrates in a format most stomachs handle better. With FTP Energy Pastilles, 2 pastilles = ~30g of carbs, so the fuelling plan becomes simple:
- Take 2 pastilles every 25–30 minutes — that's 60–70g per hour, scale up to hit 90g on harder efforts
- Chewing naturally paces your intake and starts carbohydrate breakdown in the mouth — easier on the gut than a syrup bolus
- One pre-portioned zip-lock bag replaces a dozen wrappers, opens easily with tired hands, and reseals
- Bought in 1kg bulk packs, the cost per gram of carbohydrate is a fraction of gel pricing
For the full head-to-head on absorption, GI comfort and race-day practicality, see our guide: Energy Chews vs Gels: Which Is Better for Endurance Sport?
A Sample 4-Hour Marathon Fuelling Plan
- 0:25 — first dose (2 pastilles or 1 gel)
- Every 25–30 min after — repeat, with water at aid stations
- Final dose ~3:30 — nothing new in the last 20 minutes; let what's on board carry you home
- Total: ~240–300g of carbs = 16–20 pastilles or 10–12 gels
Fuelling starts before race day too — see Carbohydrate Loading for Running: Does It Still Work? for the 48-hour build-up, and What to Eat During a Marathon for the complete race-day plan.
Frequently Asked Questions
How often should you take energy gels during a marathon?
Every 20–30 minutes once you start fuelling (from ~25 minutes in), always with water. Waiting 45+ minutes between doses creates peaks and troughs that end in the wall.
Can you run a marathon without gels?
Yes — gels are just one carb-delivery format. Chews, pastilles and carb drinks hit the same 60–90g/hour targets. Many runners find solid chews easier to stomach late in the race. Whatever you choose, test it on long training runs first — never on race day.
How many chews instead of gels?
2 FTP pastilles ≈ 30g of carbs ≈ 1.2 gels. For 60–90g per hour, that's 4–6 pastilles hourly, taken 2 at a time — easier to space out than gulping full sachets.
What happens if you under-fuel?
Glycogen stores run out somewhere around 90–120 minutes of hard running. Under-fuel and you'll slow dramatically in the final 10K — the classic "wall" is a fuelling failure, not a fitness one.
👉 Try FTP Energy Pastilles with a Taster Pack — test them on your next long run and see why more runners are leaving gels behind.
