GPS Accuracy (or lack thereof)

[MightyDuck001]

Question--
I've been using a couple of different apps for my phone to track miles, splits, etc. and I've begun noticing on the longer runs that they're wildly inaccurate. Runkeeper has me doing a 3 minute and 29 second mile. This is, needless to say, impossible. Endomondo did the same thing to me, except with a 22 second mile, so that was replaced by Runkeeper. I thought it was my iphone, but it doesn't happen every time on every run or even in the same areas so I don't know what the problem is.

My frustration with this is incredible. I have a half marathon coming up in three weeks and I don't want to be shortchanging my long runs by almost 3 miles, I don't know what I ran today or how long it took me. Okay, I'm freaking out. How do I compensate for this? Would a Garmin be a good idea or do people have problems with the accuracy of those as well?

 

[Big Vic]

Last week my Garmin (405) had me .4 miles short of my total mileage, and showed I ran one segment at 51.9 MPH. It could have been any one of a number of factors. One way to check/determine your desired mileage is to plot or drive your course. I use MapMyRun (there are others out there) to give me a estimate.

 

[Suited Deuces]

I have never had a problem with my Garmin (405)....really love it.

Distances have always been accurate....speeds, while running jump around a lot, but settle or average out over a distance. I have found that setting a pace in a workout, it seems to average out pace for a more accurate, steady pace reading.

 

[VickiHD]

I've gone through 2 of the Garmin 210 Forerunners---they both have been defective.

So now I am back using my Nike running appt on my iphone and the accuracy is not perfect either !!! It's off on both time and distance.

 

[Big Vic]

I have never had a problem with my Garmin (405)....really love it.

Distances have always been accurate....speeds, while running jump around a lot, but settle or average out over a distance. I have found that setting a pace in a workout, it seems to average out pace for a more accurate, steady pace reading.

Normally my 405 is pretty accurate. Hard to say what the issue was last week. Stuff happens.

 

[tedhowe]

I used RunKeeper for my early runs when I started running in the winter, but once the leaves came in on the trees, they interfered with the GPS enough that I was seeing as much as 7 - 9% variance from distances that I already knew.

It was driving me nuts as well... not as much as distance, because you can always use sites like mapmyrun.com or gmap-pedometer.com (my personal favorite) to check distance either before or after the run.

The thing that drove me nuts was pace... because of the inaccurate GPS, run keeper's pace was all over the place.

I got a Garmin 610 with the foot pod. Much better GPS accuracy (usually within about 1%) and with the properly calibrated foot pod, instant pace is very accurate as well.

 

[Figment1990]

I used RunKeeper for my early runs when I started running in the winter, but once the leaves came in on the trees, they interfered with the GPS enough that I was seeing as much as 7 - 9% variance from distances that I already knew.

It was driving me nuts as well... not as much as distance, because you can always use sites like mapmyrun.com or gmap-pedometer.com (my personal favorite) to check distance either before or after the run.

The thing that drove me nuts was pace... because of the inaccurate GPS, run keeper's pace was all over the place.

I got a Garmin 610 with the foot pod. Much better GPS accuracy (usually within about 1%) and with the properly calibrated foot pod, instant pace is very accurate as well.

Forgive me for my probably dumb question- can you use the footpod if you also do speed intervals? I have a garmin 610 also and I mostly use it on a track and have found it to be off by about .01-.03 of a mile per lap so I usually just hit the lap button each lap instead of using the auto lap and look at the pace for each lap instead of each mile. Then I just use the overall time and the accurate distance I know I've gone to calculate a real pace and enter it into my running log app (not a gps app or anything). I've heard that gps has a hard time when u are running tight corners like on a track so I figured it was either do the lap thing as I am or get the foot pod. But I wasn't sure how the foot pod worked with speed intervals, etc.

I do think my garmin is fairly accurate when running roads or even our jogging trail (which has distances marked). Off maybe a few tents but definitely not miles! I'm very happy with it.

 

[cewait]

Question--
I've been using a couple of different apps for my phone to track miles, splits, etc. and I've begun noticing on the longer runs that they're wildly inaccurate. Runkeeper has me doing a 3 minute and 29 second mile. This is, needless to say, impossible. Endomondo did the same thing to me, except with a 22 second mile, so that was replaced by Runkeeper. I thought it was my iphone, but it doesn't happen every time on every run or even in the same areas so I don't know what the problem is.

My frustration with this is incredible. I have a half marathon coming up in three weeks and I don't want to be shortchanging my long runs by almost 3 miles, I don't know what I ran today or how long it took me. Okay, I'm freaking out. How do I compensate for this? Would a Garmin be a good idea or do people have problems with the accuracy of those as well?

The problem is simple.... You are using a smart phone when you should be using something actually designed for the application. Phones triangulate off of cell towers. Quite often they will place you a good quarter mile off. Usually with time they will work their way to a couple hundred feet or closer, if you are not moving. I have found that most of the time these apps are close enough for getting an ideal of what you ran. Compare this with a GPS based unit where the accuracy is generally less than 15-20 feet at its worse. The inconsistency depends on signal strength from the cell towers and their current traffic.

From a coach's perspective, if you are off a mile or so in training, you have most of your miles under your belt and you should do fine in your race. Have a fun race.

 

[cewait]

I've gone through 2 of the Garmin 210 Forerunners---they both have been defective.

So now I am back using my Nike running appt on my iphone and the accuracy is not perfect either !!! It's off on both time and distance.

Look at your instructions for calibration. Then take your Nike to a high school tack and run one mile... 4 laps. Make sure you stay with a similar speed and run/walk ratio if you run walk. Do a calibration anytime you take the pod out of a shoe to replace batteries. That is not 100% necessary, but anytime you change the angle and orientation of the foot pod, it can affect the calibration .

Last week my Garmin (405) had me .4 miles short of my total mileage, and showed I ran one segment at 51.9 MPH. It could have been any one of a number of factors. One way to check/determine your desired mileage is to plot or drive your course. I use MapMyRun (there are others out there) to give me a estimate.

This is not too uncommon... It generally triggers from missing data. Were you around buildings or trees?

Forgive me for my probably dumb question- can you use the footpod if you also do speed intervals? I have a garmin 610 also and I mostly use it on a track and have found it to be off by about .01-.03 of a mile per lap so I usually just hit the lap button each lap instead of using the auto lap and look at the pace for each lap instead of each mile. Then I just use the overall time and the accurate distance I know I've gone to calculate a real pace and enter it into my running log app (not a gps app or anything). I've heard that gps has a hard time when u are running tight corners like on a track so I figured it was either do the lap thing as I am or get the foot pod. But I wasn't sure how the foot pod worked with speed intervals, etc.

I do think my garmin is fairly accurate when running roads or even our jogging trail (which has distances marked). Off maybe a few tents but definitely not miles! I'm very happy with it.

GPS units do a great job except in corners. The logic in the receiver (watch) tries to predict the next point in an effort to save memory. Running elongated circles drive the logic crazy so if you look at your run map you will see they are all over the place. Go out and calibrate the foot pod and do all track work with the pod turned on. You will not get a map as the speed and distance will be from the foot pod data.

 

[JimB.]

I have found anything that is not a "dedicated" GPS to be lacking in accuracy. Every app I have ever used on my phone is off (which I guess is due to the processor not being able to run my 765,423 apps simultaneously).

I am a firm believer in the accuracy of Mr. Garmin. I have found when my distance is not what I expect, it is due to not "running the tangents" and zig-zagging a lot.

 

[jenifred]

DH has the Garmin 205 and I have the Nike+ wristband. The Garmin has been pretty accurate for the DH and he likes it. I find it to be bulky. The Nike pod system is pretty accurate once calibrated. It is also very slim. However, the pod sysytem does not work well with interval training, because your stride is different between a walk and run. This will cause inaccuracy in the total distance. So I use the pod for monitoring my pacing during the run. But I use MapmyRun/Logmyrun to calculate my total distance and overall pace.

 

[Reep]

I used the Garmin 310, and now use the Nike Sportswatch+ and both were very accurate in terms of mileage. The Garmin was probably better at instant pace. The Nike has been inconsistent at pace. I don't trust it enough to use the pacing during a race, but the Nike watch has nice features, so I plan on using it at DL half, but I will mark my own laps.