Marathon Fueling by Finish Time: Gel Schedule That Matches Your Pacing Plan
Your pacing plan and fueling plan must match. If you pace like a 3:10 marathon but fuel like a 4:30 marathon — or vice versa — the last 10–12K gets ugly.
This guide gives you simple fueling targets by finish time (carbs/hour), converts them into gels/hour, and shows you when to take each gel so it fits your pacing checkpoints. You can also use the Marathon Fueling Calculator to generate a gel-by-time fueling schedule based on your finish time.
How to use this guide
This page is meant to connect fueling decisions to real marathon pacing, not just list gel timings. At MarathonPaceKM, the goal is practical execution: pick a realistic finish time, match that to an hourly carb target, then choose a schedule simple enough to execute when tired. A fueling plan only works if pacing stays controlled enough for your gut to cooperate.
The 5 fueling principles that don’t change
-
Fuel by minutes, not by kilometres.
Absorption is time-based; your pace and distance covered per hour can change with hills, wind, and fatigue. -
Start early.
It is easier to maintain carbohydrate availability than to catch up after you crash. -
Consistency beats hero doses.
Smaller, regular intakes usually reduce GI risk versus big, infrequent hits. -
Practice your exact plan in training.
Higher carb intakes such as 60–90 g/h can work well in long endurance events, but only if practiced first. -
Pacing and fueling interact.
If you overpace early, gut blood flow can drop and your stomach stops cooperating. Your fueling plan cannot save bad pacing.
This is one place where controlled marathon training helps. Runners using Norwegian Singles for marathon training often benefit because better control of threshold effort can make it easier to fuel consistently without stomach trouble.
Carb targets by finish time (simple)
General guidance commonly used in endurance sports suggests around 30–60 g carbohydrate per hour for many endurance sessions and events, with higher intakes up to around 90 g/h potentially beneficial for longer events, especially when using multiple transportable carbohydrates and practicing the strategy in training.
| Finish time | Carb target (g/hour) | Why this range | Default strategy |
|---|---|---|---|
| < 2:45 | 60–90 g/h | High intensity + long enough to benefit from higher intake if trained | Start early, frequent small doses, mix glucose + fructose products |
| 2:45–3:30 | 60–90 g/h (often 60–75 as a practical start) | Still long enough that consistent fueling pays off | 20–30g every ~20 min or 25g every ~25 min |
| 3:30–4:30 | 45–75 g/h | Long duration; GI tolerance varies; consistency matters most | 20–25g every ~20–30 min |
| 4:30+ | 30–60 g/h | Very long duration; prioritize fueling you can keep down | 15–25g every ~25–35 min + sports drink as tolerated |
Gel math: convert grams/hour → gels/hour
Most gels contain roughly 20–30 g of carbohydrate. Always check the label. Use this formula:
Practical tip: do not obsess over perfect math. Build a schedule you can remember: every 20 minutes, every 25 minutes, or every 30 minutes.
Fueling schedules (by finish time)
Below are default schedules that work for many runners. They assume ~25g carbs per gel. If your gel is 20g, you will need slightly more frequent gels. If it is 30g, slightly fewer.
Schedule A: Sub-2:45 (or very aggressive pacing)
Target: 75–90 g/h
| Time | Fuel | Notes |
|---|---|---|
| 0:20 | Gel (25g) | Start early; don’t wait |
| 0:40 | Gel (25g) | Chase with water |
| 1:00 | Gel (25g) | Or sports drink equivalent |
| 1:20 | Gel (25g) | Small, regular doses |
| 1:40 | Gel (25g) | Adjust if stomach tight |
| 2:00 | Gel (25g) | Late-race insurance |
| 2:20 | Gel (optional) | Only if tolerated |
How it matches pacing: plan gels at 20-minute blocks; align with your 5K/10K checkpoints using your pace band.
Schedule B: 2:45–3:30 (most serious PB marathoners)
Target: 60–75 g/h (up to 90 g/h if trained)
| Time | Fuel | Notes |
|---|---|---|
| 0:25 | Gel (25g) | Or 0:20 if you’re GI-robust |
| 0:50 | Gel (25g) | Water after |
| 1:15 | Gel (25g) | Keep it boring |
| 1:40 | Gel (25g) | Don’t delay this one |
| 2:05 | Gel (25g) | Common wall-window prevention |
| 2:30 | Gel (optional) | Based on tolerance and effort |
| 2:55 | Gel (optional) | Late push helper |
Simple memory hook: “Every 25 minutes.”
Schedule C: 3:30–4:30
Target: 45–75 g/h (start lower if GI sensitive)
| Time | Fuel | Notes |
|---|---|---|
| 0:30 | Gel (20–25g) | Start early even if easy |
| 1:00 | Gel (20–25g) | Or sports drink |
| 1:30 | Gel (20–25g) | Small sips of water |
| 2:00 | Gel (20–25g) | Stay consistent |
| 2:30 | Gel (20–25g) | Adjust if GI tight |
| 3:00 | Gel (optional) | Often helpful |
| 3:30 | Gel (optional) | Only if tolerated |
Simple memory hook: “Every 30 minutes.”
Schedule D: 4:30+
Target: 30–60 g/h (fuel you can keep down > perfect numbers)
| Time | Fuel | Notes |
|---|---|---|
| 0:35 | Gel (15–25g) | Or sports drink + small gel |
| 1:10 | Gel (15–25g) | Water after |
| 1:45 | Gel (15–25g) | Walk stations if needed |
| 2:20 | Gel (15–25g) | Consistency wins |
| 2:55 | Gel (15–25g) | Adjust for nausea |
| 3:30 | Gel (optional) | Only if tolerated |
| 4:05 | Gel (optional) | Late support |
Simple memory hook: “Every 35 minutes.”
How to match gels to your pacing plan
Here’s the easiest way to marry fueling with pacing:
- Pick a time-based gel interval: every 20 / 25 / 30 / 35 minutes.
- Convert that into kilometre landmarks using your goal pace if useful.
- Put gels near low-chaos moments: after a hill, after a turn-heavy section, before a long exposed segment.
- Attach gels to aid stations: gel just before station → water at station → keeps it simple.
Hydration & sodium basics (don’t overcomplicate)
Hydration needs vary massively. A classic ACSM position stand emphasizes starting euhydrated and replacing fluids during exercise in a way that limits excessive dehydration while avoiding overdrinking.
A simple, safe framework
- Start hydrated (normal urine colour; don’t flood the system).
- Drink early, sip often rather than huge boluses.
- In heat or humidity, plan more fluid and consider extra sodium, but practice it first.
Sodium: when it matters
Sodium needs depend on sweat rate and sweat sodium concentration. A commonly cited endurance guideline is roughly 0.5–0.7 g sodium per liter of sports drink in some situations.
For hot or stressful race days, pair this with Marathon Pacing in Heat, Wind, and Hills.
Gut training: how to practice this safely
Higher carb intake targets such as up to ~90 g/h in long events should be trained progressively to improve tolerance.
4-step progression
- Start at 30–40 g/h on long runs.
- Move to 50–60 g/h once your stomach is calm.
- Then 60–75 g/h for marathon-specific long runs.
- Only then consider 75–90 g/h if your goals and tolerance support it, often aided by multiple-transportable carbs like glucose + fructose.
Practice sessions: long runs with marathon-pace blocks are the best place to rehearse fueling under race-like stress.
This is where structure matters more than theory. See Marathon Pace Workouts and Norwegian Singles vs Tempo Runs if you want to think about how workout design affects fueling practice quality.
Common mistakes (and fixes)
- Waiting until you feel low to start fueling.
Fix: start at 20–35 minutes, then repeat on schedule. - Trying a new gel brand on race day.
Fix: nothing new on race day; practice exact products. - Big, infrequent gel hits.
Fix: smaller, more regular doses. - Water-only with lots of gels.
Fix: ensure some sodium via sports drink or electrolytes as practiced; don’t overdrink. - Overpacing early and blaming the stomach.
Fix: cap effort early so fueling stays possible.
If you repeatedly turn controlled training into hard grinding, that usually hurts fueling tolerance too. In that case, read Who Should Not Do Norwegian Singles.
Race-day checklist (copy/paste)
- ✅ Goal time + pace band printed: Printable Pace Band
- ✅ Fuel target chosen (g/h) and tested in training
- ✅ Gel interval chosen: every 20 / 25 / 30 / 35 minutes
- ✅ First gel time set (20–35 minutes)
- ✅ Water plan: sip at stations; avoid overdrinking
- ✅ Sodium plan if needed, practiced in training
- ✅ No hero-start rule to protect gut + pacing
Recommended marathon fueling products
Many marathon runners use a combination of gels and carbohydrate drink mixes during long runs and races. The best choice is the one you can tolerate, remember to take, and repeat under marathon effort.
| Product | Best for | Typical use |
|---|---|---|
| Maurten Gel 100 | Runners who want simple carb delivery and minimal flavour | Used as a standard gel within 20–30 minute schedules |
| GU Energy Gel | Runners who want lots of flavour options and easy availability | Works well when building a repeatable gel-by-time plan |
| SiS Beta Fuel Gel | Runners pushing higher carb targets per hour | Useful when trying to reduce how often you need to take gels |
| Tailwind Endurance Fuel Drink Mix | Runners who prefer drinking part of their carbohydrate intake | Can support gels or replace some gel intake on longer runs |
Disclosure: Some links on this page are affiliate links. This means MarathonPaceKM may earn a small commission at no extra cost to you.
FAQ
How many gels should I take in a marathon?
Convert your carb target in g/h into gels/hour using your gel’s carb grams. Many runners aim for 30–60 g/h in some endurance contexts, and up to 60–90 g/h in longer events if practiced.
When should I take my first gel?
Usually within 20–35 minutes, then repeat on a fixed schedule. Starting early is easier than trying to catch up later.
Should I fuel by kilometres or by minutes?
Minutes. Use kilometres only as a convenience for matching to checkpoints.
Is 90 g/h right for everyone?
No. It can be beneficial for long events but must be practiced progressively to reduce GI distress.
Do I need electrolytes or sodium?
It depends on sweat rate and conditions. Some guidance discusses sodium in drinks such as ~0.5–0.7 g/L and emphasizes appropriate hydration without overdrinking. Practice your approach.
About MarathonPaceKM
MarathonPaceKM publishes practical pacing tools, calculators, and training guides designed to help runners make better decisions from race data, pacing logic, recovery context, and real-world training feedback.
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Related pages: Marathon Fueling Calculator · Marathon Pace Calculator · Norwegian Singles · Norwegian Singles for marathon training
References
- Jeukendrup A. (2014). Carbohydrate Intake During Exercise. PMC
- Burke LM, et al. (2011). Carbohydrates for training and competition. PubMed · Full text
- IOC Consensus Statement on Sports Nutrition (2010). PDF
- Cao W, et al. (2025). Carbohydrate Supplementation: Endurance Performance. PMC
- Sawka MN, et al. (2007). ACSM Position Stand: Exercise and Fluid Replacement. PubMed · PDF
- ACSM Health & Fitness Journal note on sodium in sports drinks (~0.5–0.7 g/L). LWW
Educational content only. If you have medical conditions or a history of hyponatremia or heat illness, consult a clinician.