Should I go with Strava or chip time for sub-3?
Strava says I’ve run sub-2:45. The chip time says I haven’t. What gives - and which one really counts?
According to Strava, my fastest ever marathon is 2:43:16 at the London Marathon 2025. My chip time? 2:45:01. How on Earth could they be so different—and which one should you go with?
While sub-2:45 is far less of a thing than sub-3, I can still feel the pain of those who see a 2:59:59 on Strava, only to get their official time through and realise they’ve missed it. It can be devastating, especially given the months - indeed years- of graft and the willpower that goes into reaching that final push.
The annoying thing is that Strava is almost certainly right. If you’re wearing a decent multi-band GPS watch (I use the Garmin Forerunner 265), even tricky areas like Canary Wharf aren’t going to throw you off too much. You’ve almost certainly run 42.2km - or more - in the time Strava shows.
So should you declare the sub-3? Absolutely not.
The marathon isn’t just about running the distance. It’s about running the course. And your chip time is the time it took you to do that. End of story.
So what’s the most likely cause of the discrepancy? In big races like London, it’s usually running long. I average 42.7km on that course, due to the sheer overcrowding in the early miles. You’ll almost certainly find yourself dodging bottles, weaving around slower runners and forced wide by crowd merges from other start zones. Every tiny deviation from the racing line adds distance—and therefore time.
The blue line is there to show the shortest legal route, and technically you can follow it the whole way to hit 42.2km exactly. But in reality, unless you’re Kipchoge or filming a promo video before the race, that’s not going to happen.
The best solution? Don’t chase your sub-3 at London - or increasingly, any of the world majors. Run them hard, sure, but treat them as celebration events. If you want a true PB attempt where chip time and Strava time actually match, pick a smaller, faster race like Yorkshire or Chester. On both of those courses, my GPS showed bang on 42.2km.
And while we’re talking about arbitrary rules, let’s not forget that the distance of the marathon - 42.195km - was only standardised in 1921 to match the exact length run during the 1908 Olympic Games in London, when the route was extended so the royal family could watch the finish from Windsor Castle. But once a rule is in place, it’s in place.
Strava is a brilliant training tool. But when it comes to race results, chip time is what counts.
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