How accurate is a GPS with factoring hill distance elevation?

George Ilie wrote:

The correct answer, although late...

The GPS sensor is for location only. The altitude information comes from databases, which is an estimation usually.

The only way to measure with high accuracy the elevation change is to have a barometric sensor.

The barometric sensor is very accurate and blazing fast.

Even so, the apps do not rely on barometer, but on databases, because there aren't many watches or devices with barometer.

So, the answer to OP is that he had estimated data about elevation, which can be very poor.

No. His watch does not contain that data.

The real answer is GPS is not very accurate and even if you run at a constant pace in a straight line, the pace will swing up and down, especially if there are lots of trees and hills surrounding you.

And if you go off-road on twisty wooded tracks will lots of hills, you may as well just guess how far you've run as you'll probably be closer than your GPS watch.

bwakem wrote:

And if you go off-road on twisty wooded tracks will lots of hills, you may as well just guess how far you've run as you'll probably be closer than your GPS watch.

Is that what DC Rainmaker's tests show ?

ExpertKipWatcher wrote:

bwakem wrote:

And if you go off-road on twisty wooded tracks will lots of hills, you may as well just guess how far you've run as you'll probably be closer than your GPS watch.

Is that what DC Rainmaker's tests show ?

Dc rainmaker has a vested interest in selling gps watches. What kip watcher told you is the truth.

ExpertKipWatcher wrote:

bwakem wrote:

And if you go off-road on twisty wooded tracks will lots of hills, you may as well just guess how far you've run as you'll probably be closer than your GPS watch.

Is that what DC Rainmaker's tests show ?

I can't find the site now but there was a comparison review where 4 or 5 of the most popular GPS watches were strapped to a measuring wheel and wheeled around a selection of courses.

On flat straight roads they were something like 2-3% out on average but on a heavily wooded bendy course the average error was > 10% and the top Garmins were around 17% out (the watches all under-read the distance due to drawing straight lines across corners and bend).

So if you run that route with one of those Garmins and it says 7:00/mile, you actually ran 5:59/mile. So totally useless.

Also they can't even repeat their own inaccuracy. I have a route that is on pretty straight roads - no possibility of corner cutting or adding/subtracting metres anywhere - my Garmin 225 has measured it as short as 8.03 miles and as long as 8.3 miles, a difference of 434m. I have measured it with mapping software and get 8.4 miles.

ExpertKipWatcher wrote:

bwakem wrote:

And if you go off-road on twisty wooded tracks will lots of hills, you may as well just guess how far you've run as you'll probably be closer than your GPS watch.

Is that what DC Rainmaker's tests show ?

Is DC Rainmaker a gps device developer?

Bwakem is right. Once the radio in the watch loses enough satellites, what little precision a gps device that fits inside a watch is lost. From there, your track is estimated until the number of satellites increases.

I know this is an ancient thread, but it is still available with some correct and some incorrect information. And I know that many hikers and runners are confused about map distance and hiking and running distance recorded by consumer level devices. So I offer this based on a 100 hiker event with many claiming that the advertised distance of 10.8 miles was short by as much as 0.7 miles with some explaining that the hills were not accounted for. Interestingly, nobody complained that the hike was shorter than advertised. Thanks to GPSVisualizer for calculating the elevation gain/loss..

Hill distance elevation is affected by only one thing - leg speed velocity

Pretty accurate. Over a decade ago, I used a Garmin to time my favorite extremely hilly 14-mile run. Then I went over it with a Jones counter (the device used to certify road races) on my bike. The GPS was within .1 miles of the exact distance. The technology has improved since then.