---
title: "Half Marathon Fueling Calculator | TrainPace"
description: "Half marathon fueling calculator. Enter your goal time to calculate carbs per hour, total carbs, and exactly how many gels you need on race day."
url: https://trainpace.com/fuel/half-marathon-fueling-calculator
---

# Half Marathon Fueling Calculator

Half marathon fueling calculator. Enter your goal time to calculate carbs per hour, total carbs, and exactly how many gels you need on race day.

Enter your half marathon goal time and get your exact fueling numbers — carbs per hour, total carbs, and gel count. No guesswork, just the math.

- Personalized carbs/hour from your goal time
- Exact gel count for your half marathon
- Works for any finish time from 75 min to 3+ hours

## How to calculate half marathon fueling

Use your goal finish time to get personalized carb and gel numbers for race day.

1. Enter your goal time: Input your half marathon target finish time.
2. Review your numbers: Get carbs/hour, total carbs, and gel count instantly.
3. Build your schedule: Turn the numbers into a simple timing plan you can execute.

## Frequently asked questions

### How accurate is a half marathon fueling calculator?

It gives you a solid starting point based on proven 60-90g/hr guidelines. Fine-tune by practicing in training — every gut is different.

### Do faster half marathons need different fueling?

Faster efforts burn through glycogen quicker, but the window is shorter. A 75-minute half needs fewer total carbs than a 2.5-hour half, even if the rate is similar.

- [Calculate Your Fuel Needs](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