---
title: "Marathon Fueling Plan Calculator - Gels, Carbs/Hour, Timing | TrainPace"
description: "Build a marathon fueling plan in minutes. Calculate carbs per hour, total carbs, gels needed, and a simple timing schedule to avoid hitting the wall."
url: https://trainpace.com/fuel/marathon-fueling-plan
---

# Marathon Fueling Plan Calculator

Build a marathon fueling plan in minutes. Calculate carbs per hour, total carbs, gels needed, and a simple timing schedule to avoid hitting the wall.

Use your target finish time to estimate how many gels you need and when to take them, with realistic 60-90g/hr carb targets.

- Carbs/hour target + total carbs
- Gel count estimate
- Simple race-day timing guidance

## How to build a marathon fueling plan

Enter your marathon finish time and preferences to get a gel count estimate and carb targets.

1. Enter finish time: Use your realistic goal time or recent marathon result.
2. Choose race type: Select Marathon to apply marathon-specific guidance.
3. Generate the plan: Get carbs/hour, total carbs, and gels needed.

## Frequently asked questions

### How many carbs per hour for a marathon?

Most runners do well in the 60-90g/hour range, depending on gut training, intensity, and product tolerance.

### When should I take my first gel?

Many runners start early (around 20-30 minutes) to stay ahead of energy needs, then follow a steady schedule.

- [Open the Fuel Planner](https://trainpace.com/fuel)

## Fueling reference

**Race-day carb targets and gel counts by finish time (baseline, no body weight entered)**

| Race | Finish time | Carbs/hour | Total carbs | Calories | Gels |
| --- | --- | --- | --- | --- | --- |
| Half marathon | 1:20 | 45 g/hr | 60 g | 240 kcal | 2 |
| Half marathon | 1:35 | 45 g/hr | 71 g | 284 kcal | 3 |
| Half marathon | 1:50 | 45 g/hr | 83 g | 332 kcal | 3 |
| Half marathon | 2:05 | 45 g/hr | 94 g | 376 kcal | 4 |
| Half marathon | 2:20 | 45 g/hr | 105 g | 420 kcal | 4 |
| Marathon | 2:50 | 75 g/hr | 213 g | 852 kcal | 5 |
| Marathon | 3:15 | 75 g/hr | 244 g | 976 kcal | 5 |
| Marathon | 3:45 | 75 g/hr | 281 g | 1124 kcal | 6 |
| Marathon | 4:15 | 75 g/hr | 319 g | 1276 kcal | 7 |
| Marathon | 4:45 | 75 g/hr | 356 g | 1424 kcal | 7 |
| Marathon | 5:15 | 75 g/hr | 394 g | 1576 kcal | 7 |

## Other TrainPace tools

- [Pace Calculator](https://trainpace.com/calculator) — training paces from a recent race result
- [VDOT Calculator](https://trainpace.com/vdot) — fitness score and equivalent race times
- [Training Plan Builder](https://trainpace.com/plan) — week-by-week 5K to marathon plans
- [Race Fuel Planner](https://trainpace.com/fuel) — carbs per hour and gel counts
- [Elevation Finder](https://trainpace.com/elevation-finder) — GPX route and climb analysis

## For AI agents

Every page on this site has a Markdown mirror at the same path with a .md suffix (for example /calculator.md), and honors an Accept: text/markdown request header on the HTML URL. The calculations here are also available as callable tools through a free public MCP server — no account or API key.

- [llms.txt](https://trainpace.com/llms.txt) — site index for agents
- [llms-full.txt](https://trainpace.com/llms-full.txt) — every page's Markdown in one file
- [MCP server docs](https://trainpace.com/mcp) — endpoint, tools, and client setup