Why Strava distance is always 0.01 mile shorter than Garmin distance?

[Silentvoyager]

I know it is a small thing but it is one of those things that is quite annoying about Strava. You know that situation when you finish a run and notice that it is very close to a round number of miles, than you run a bit further to make it e. g. 5 miles. Then it uploads to Strava and shows as 4.99 miles in some parts of the app and 4.9 miles in other parts of the app (e. g. the training calendar). Can Strava stop doing that? 

[varun · Accepted solution]

Hi @Silentvoyager, 

We know this has been a long-time quirk, and often a frustration for many athletes, including some of our own employees! The reason this happens is that Garmin (both the device and Garmin Connect) rounds up distances, whereas Strava rounds down. Distances are always stored in meters on devices and then shown on Strava in the athlete's preferred units (i.e. miles/yards for imperial and kilometers/meters for metric). So for example, a distance that comes over in a file as 4995 meters will get displayed on Strava as 4.99 km and on Garmin as 5.00 km. Similarly, if on your watch you run until you see 1.00 miles, that might actually be something like 1608.0 meters (0.9994 miles) and Strava will show 0.99 miles.

It is also worth clarifying that most Garmins, even relatively older ones, provide a distance directly in the file that Strava uses. There are cases we calculate distance ourselves from the raw GPS points; for example, if a certain device doesn't provide it. And athletes can also choose to use our calculated distance to override the device one - see How Distance is Calculated for more. 

One other nuance for the question from @MattS_bsb regarding race distances like a half marathon or marathon. There are features like Best Efforts and Challenges based on those Best Efforts that require athletes to complete a certain distance. One thing we have seen is athletes who run 26.2 miles and not receiving credit. This stems from the same issue above - that a marathon is 26.22 miles when converted from its official distance (26 miles and 385 yards), and athletes are often slightly short.

We understand that this is a bit of a philosophical stance we've taken - the digital version of "running all the way to the line". There is a tradeoff here between the consistency with Garmin and satisfaction of the round numbers (because yes, we've all been there), and the care we aspire to take with data correctness and integrity. This is one of an exceedingly long list of nuances around data as we pursue making Strava work for thousands of devices, each with its recording subtleties and differences.

Hopefully that helps clear things up and explains why you might see some crafty athletes running til they see 1.01 on the watch. We will strive to continue using this forum as a place to transparently explain more of these types of situations to athletes.

[SoCalRK]

Not a big deal, but Strava always shows avg speed a tenth or two lower than my Garmin. On some rides it takes a bit of effort to get those 10ths! Why can’t Strava just accept the exact numbers from Garmin device without manipulating them?!! Is Strave the ‘ride police’ to enforce their interpretation of a ride that Garmin recorded? 

[STM]

It’s my understanding that this is also impacted by what Garmin considers moving v. Stopped being different than how Strava views it- not sure how it could possibly be different, but apparently it is.

would be great to see some sort of universal standard here.

[MattS_bsb]

It's not just Garmin; I have friends who run with COROS and Apple watches and suffer the same "tax" when activities are uploaded to STRAVA.

[Rogier]

Strava does the right thing, Garmin gets it wrong. Distances should always be rounded down, times always rounded up. That's how it's done at races per the rules of World Athletics.

The official marathon distance is 42.195 km; the official distance in miles doesn't exist since converting 42.195k into miles gives you an infinite number of digits behind the dot. Running even a fraction of a nanometer less means it's not a marathon and any record or Boston Qualifier won't count.

[Martintcurran]

If you could help me! I’m almost 65 and using running, and mountain running, as my physical and mental health tool. Using my Garmin watch and Strava I just registered a 5:51 mile. What does that translate into minutes and seconds? Thank you!!

[Silentvoyager]

This keeps coming up in social networks regularly. There are always a lot of misconceptions about what everyone refers to as "Strava tax", but I think at the end that simply harms reputation of Strava. It would be better for Strava to stop being stubborn about this issue and make distances match to Garmin and other brands by doing proper rounding.

https://www.reddit.com/r/Strava/comments/128fzjh/why_does_strava_apply_a_penalty_of_10m_to_every/?ut...

[MattS_bsb]

This also comes up in group runs where there's a goal distance (say 10 miles), and when folks are approaching the end of the run/distance, I'll usually remind folks to "round up for STRAVA!!".  We've all endured that slight sting of seeing our final distance show up as .99.  Oh by the way, I've seen STRAVA tax become a real thing for myself and others using indoor rowers (no GPS), usually around 3 meters.  Weird right?

[Silentvoyager]

I wanted to add two more points to this thread.

1) Strava's rounding down of the distance is well known and disliked on Reddit (e.g. r/running subreddit), and often mentioned and referred to as "Strava Tax". If nobody likes that, why Strava insists on doing that? 

2) The same rounding down seems to apply to elevation gain. 

[CreakyCrank]

@Silentvoyager To your first point, I believe what @varun is saying in the response when they refer to "the care we aspire to take with data correctness and integrity. " is that Strava is not going to round up, because they are more concerned with data correctness and integrity, or "running all the way to the line".  - basically, they (Strava) are ensuring that you go the full distance, and not rounding up ensures this... you have to 'cross that virtual finish line'.

Elevation would also apply (but this is even more of a contentious issue, and your elevation will vary wildly from device to device).  I don't count on any device to be accurate with elevation numbers - I can ride next to others and have a variation in elevation between us of 100s of feet (or meters/metres if you prefer metric)... I can complain all day about elevation! (but it really has nothing to do with Strava when the GPS devices are so varied in the numbers it gives).

I know the "Strava Tax" can be frustrating/upsetting, and can cause an athlete to not get a completion of a certain distance, but I don't think Strava will start rounding up anytime in the near future... my best advice is to run/ride a bit further than the distance you are looking to achieve, or climb a little bit higher (also, this is likely not the answer you are looking for, but it is the only solution based on @varun's response on Strava's methodology).