Run your race, not someone else's.
Enter your goal time, the marathon course, and race-day conditions. Get a course-adjusted pacing plan with mile-by-mile splits that account for elevation, weather, and your experience level.
Marathon goal time
Format: H:MM:SS or H:MM (e.g., 4:00:00 or 4:00)
Marathon course
Race conditions (optional)
Experience level
Marathon pacing guide
Why even-effort pacing wins.
The fastest marathon you will ever run is the one where the second half is the same speed as the first. Negative splits are even better, but rare. Positive splits are common, expensive, and almost always self-inflicted.
The biggest pacing mistakes are predictable. Going out 10 to 20 seconds per mile faster than goal pace because the first miles feel easy. Ignoring the elevation profile and assuming flat splits will work on a course that is anything but. Treating heat and humidity as variables that affect other people's races.
A good pacing plan does three things: it sets a realistic goal time, it adjusts the splits for the course you are actually running, and it gives you a target for each mile that accounts for whether the road is going up, down, or just lying to you about being flat.
| Goal time | Average pace | Even-effort start (mi 1–5) | Steady middle (mi 6–20) | Strong finish (mi 21–26.2) |
|---|---|---|---|---|
| 3:00 | 6:52/mi | 6:55 | 6:52 | 6:48 |
| 3:30 | 8:00/mi | 8:05 | 8:00 | 7:55 |
| 4:00 | 9:09/mi | 9:15 | 9:09 | 9:00 |
| 4:30 | 10:18/mi | 10:25 | 10:18 | 10:10 |
| 5:00 | 11:27/mi | 11:35 | 11:27 | 11:18 |
| 5:30 | 12:36/mi | 12:45 | 12:36 | 12:25 |
Pacing FAQ
Common pacing questions.
Use the calculator above for course-specific splits, then sanity-check the strategy against your training paces and race-day conditions.
Should I aim for a negative split?
Yes, when conditions allow it. A second half 1 to 2 percent faster than the first reduces the chance of late-race blowups. On hot days, hilly courses, or first marathons, an even split is a more realistic target.
How do I adjust for hills?
Add 5 to 8 seconds per mile on uphills and subtract the same on downhills to keep effort even. The calculator does this automatically once you select a course with elevation data.
What if race-day conditions are different?
Use perceived effort or heart rate as the primary guide. Pace targets are useful only as long as they match the conditions you trained for. Adjust by 5 to 15 seconds per mile in heat above 65°F.
Should I use a pace group?
Yes, with caveats. Pace groups are useful for steady cruising on flat courses but can pull you off plan on rolling terrain. Stay near the group on the flats, run by effort on the climbs.
How accurate is GPS for pacing?
Good enough on open road, unreliable in tunnels, between tall buildings, and on tight turns. Manual mile splits using race-marked miles are more accurate than GPS in those sections.
What is the most common pacing mistake?
Going out too fast. Most marathon disasters are decided in the first 8 miles, not the last 8. The early miles always feel easier than they should because they are.
Build the plan around your race.
Course-specific pacing is one piece. Now build the training that gets you there.