[go do it]

I searched but no dice. I found information on elevation but not on grade accuracy.

Are Strava's grade percentages accurate?

 

[arai_speed]

I searched but no dice. I found information on elevation but not on grade accuracy.

Are Strava's grade percentages accurate?

I would say some are and I would say some are not.

Longer segments on dedicated climbs tend to be accurate (when compared to my Garmin 500) when compared to shorter segments (say a residential street with a steep but short climb) will tend to be less accurate or just plain wacky! I've seen 56% grades for example.

 

[Kerry Irons]

I searched but no dice. I found information on elevation but not on grade accuracy.

Are Strava's grade percentages accurate?

Surprised you didn't find anything because this has been discussed at great length and repeatedly. Try searching just on Strava and then ignore the stuff that doesn't deal with grade and altitude.

 

[spdntrxi]

in a nutshell... by itself (just your phone) it's not to great. Upload from a cpu that use GPS and you are better off. I only upload using my Garmin to strava.

 

[looigi]

AFAIK, in the US it's based on USGS topo data, which has fairly wide spread data points and is also old. Grades will be the average between crossing two contour lines, which themselves are smoothed. There's a local stretch here where a big cut was made and the road widened about 15 years ago. The topo data predates that so Strava shows a very steep climb and descent where there's only single gradual grade now.

GPS elevation accuracy isn't great due to satellite geometry considerations so Garmin adds barometric sensors for elevation and grade. These suffer from drift and atmospheric pressure changes. The best is to use corrected baro data, which is available on Garmin Connect, for example. With this, baro data is used but adjusted to get it to agree with map data over longer distances.

 

[Typetwelve]

Not super accurate. I've seen some climbs that are off and register in strange ways. We have a local short, very steep climb that climbs, flattens very slightly then gets really nasty. Strava will show it as a climb, a short down grade then climb again...I assure you, that climbs does NOT have any down grade to it in the slightest.

I just write it off to nothing being perfect...

 

[AndreyT]

Are Strava's grade percentages accurate?

Strava (or any other similar software/hardware tool) has no access to any instruments that would measure grade directly. Grade is not measured, it is calculated. It is calculated as a ratio between the total elevation gain and planar projection of the total distance traveled. This gives you average grade for any given segment.

So it all boils down to how precise the elevation measurement is and how precise the distance measurement is. As for the calculation itself, it is as precise as it gets. After all, it is just a simple arithmetic division.