Achieve A Sub 90 Minute Half Marathon
Ticked off in March 2026
Ninety minutes, 21.1 kilometres and not a second to spare, the half marathon time that marks you out as properly quick.
The adventure
Sub-90 sits in a cruel place. It is fast enough that you can't coast any part of it, and long enough that an overexcited first 5K will cost you dearly in the last three miles. The target is just under 4:16 per kilometre, mile after mile of 6:52s, and your watch becomes the most important thing in the world.
Many big races put out pacers with 1:30 flags, and running in that group is an experience in itself: a pack of focused runners breathing in rhythm, the pacer calling out splits, people dropping off one by one after 15 kilometres. If you can hang on and kick through the final mile, you cross the line with a one, a two and a nine on the clock, and the feeling is very different from simply finishing.
Why it’s epic
- The required pace is just under 4:16 per kilometre, or 6:52 per mile.
- Most major half marathons provide official pacers, usually including a 1:30 group.
- Flat races such as the Cambridge Half Marathon, which runs past the city's historic colleges, are ideal for a fast time.
- A sub-90 half suggests a marathon of around 3:10 is within reach.
What it is
A sub-90-minute half marathon means averaging under 4 minutes 16 seconds per kilometre for 21.1 kilometres.
How to do it
Follow a 12-week plan with long runs, tempo and interval work, and race on a flat course.
Top tip
Run with a pacer if the race has them.
Need to know
- Most runners need a 10K time of around 41 minutes or faster before a sub-90 half is realistic.
- Pick a flat spring or autumn race and warm up properly, as you need to be on pace from the first mile.
My experience
Ticked off, but the full story is still to be written up.
Over to you
Is “Achieve A Sub 90 Minute Half Marathon” on your bucket list, or have you already done it? Tell me in the comments, and if you've got a question about it, ask away and I'll answer.