Racing smarter
What pace is a 1:45 half marathon?
1:45:00 for the half marathon is 4:59/km (8:01/mi), held the whole way. Halfway on even pace is 52:30. Most watches measure the course long, so the pace you actually need on the screen is nearer 4:54/km.
| What | Number | The qualifier |
|---|---|---|
| Pace needed | 4:59/km (8:01/mi) | even, start to finish |
| Halfway (even) | 52:30 | 53:33 on a 2% negative split |
| Watch pace at 1.5% overage | 4:54/km (7:53/mi) | what the screen has to show |
| Distance | 21.0975 km (13.11 mi) | the measured course, not the watch |
What pace is a 1:45 half marathon?
1:45:00 over 21.0975 km (13.11 mi) is 4:59/km (8:01/mi), held from the first step to the last. There is no rounding slack in that number: run the first kilometre at 5:09/km and you have already spent ten seconds you will not get back cheaply.
1:45 is 4:59/km (8:01/mi), which makes the arithmetic pleasant: five minutes a kilometre, all the way. It is a common second-half-marathon goal and it maps to roughly a 48-minute 10K. Training is typically four days a week at 35 to 50 km with one longer run of 16 to 18 km. The failure mode is the middle. This distance is short enough that the start feels easy and long enough that the last 5 km hurt, and the section people lose is between 12 and 17 km, where concentration goes and the pace drifts to 5:10 without it feeling different. Take a split every kilometre through that stretch rather than every five.
What the splits look like
| Kilometre | Split | Elapsed |
|---|---|---|
| 1 | 4:59 | 4:59 |
| 5 | 4:59 | 24:53 |
| 10 | 4:59 | 49:46 |
| 15 | 4:59 | 1:14:39 |
| 20 | 4:59 | 1:39:32 |
| 21.0975 | 0:29 | 1:45:00 |
And in miles, for a course measured that way:
| Mile | Split | Elapsed |
|---|---|---|
| 1 | 8:01 | 8:01 |
| 3 | 8:01 | 24:02 |
| 6 | 8:01 | 48:03 |
| 9 | 8:01 | 1:12:05 |
| 12 | 8:01 | 1:36:07 |
| 13.11 | 0:53 | 1:45:00 |
Where should I be at halfway?
Even pace puts you through halfway at 52:30. Most people who finish this time went through slightly slower than that, not faster — a 2% negative split means halfway at 53:33 and a second half of 51:27.
The decision rule for race day: if you reach halfway more than 1:03 ahead of 52:30, you are not ahead of schedule, you are borrowing. Ease back to 4:59/km (8:01/mi) and hold it.
What if my watch measures the course long?
Almost every watch does. A half marathon that reads 1.5% long on your wrist means you have to run 4:54/km by the watch to finish in 1:45:00 by the clock. That is the pace to put on the screen, and it is why pacing off a watch's average-pace field alone tends to leave people a minute or two short.
Questions runners actually ask
- Is a 1:45 half marathon a good time?
- Good is a comparison, and it depends who with. Whether it is achievable for you is the answerable question: it comes down to a recent race, your weekly volume and your longest run. The race predictor puts numbers on all three.
- Should I run even splits or negative splits?
- Even, planned; slightly negative, executed. Going through halfway 1-2% slower than even pace costs almost nothing if you are strong at the end, and saves the race if you are not.
Sources
- Hanley B et al. Pacing profiles of senior athletes at the World Athletics Championships. Front Sports Act Living 4:964905, 2022 primary
- Deaner RO et al. Men are more likely than women to slow in the marathon. Med Sci Sports Exerc 47(3):607-616, 2015 primary
- World Athletics Competition Rules, Book C2.1 — course measurement and the short course prevention factor reference
Changelog
- — First published.