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I'm working on a project for class, and I'm mapping GPS on Google Earth with a KMZ file. I used a handheld GPS 24°6.691'N + 74°27.833'W.

How accurate is my coordinates? I know I'm in decimal minutes!

PolyGeo
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OneTimer
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    The accuracy of GPS coordinates is not a matter of displayed digits, but a question of reception quality. The DOP value tells you how good that is. Good GPS receivers show you that value. – AndreJ Jun 19 '14 at 18:31
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    Another thing to keep in mind is the accuracy of the base map/other layers that your points will be displayed on (Google Earth in your case). Even if you have a perfectly accurate GPS (which doesn't exist), the photography could still be off by several meters. – Evil Genius Jun 19 '14 at 18:47
  • I guess the better question should be, what are the parameters in precision? I know it's something like .001 decimal places are accurate up to 300 ft, but I feel like that isn't right for my coordinates. – OneTimer Jun 19 '14 at 20:05
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    Discussions of precision (and how it differs from accuracy) are in How to measure the accuracy of latitude and longitude?. Since a decimal minute is at most 111 (or so) kilometers, your three decimal digits are precise to about 111 meters (north-south) and a little better east west. – whuber Jun 19 '14 at 20:26
  • It's not right, because you're confusing the precision of decimal degrees with the precision of decimal minutes. http://gis.stackexchange.com/questions/8650/how-to-measure-the-accuracy-of-latitude-and-longitude covers degrees, while http://wiki.xkcd.com/geohashing/GPS_accuracy covers the decimal measure of degree, minutes, and seconds. – Chris W Jun 19 '14 at 20:32
  • @whuber Would it be worth modifying your answer at the linked question to include a table like the wiki.xkcd link I put in my comment so that it shows the relative precision of decimal minutes and seconds as well as degrees? – Chris W Jun 19 '14 at 20:39
  • One thousandth of a minute of latitude is about 1.85 meters. – Martin F Jun 19 '14 at 21:23
  • @Chris Of course you're right--I mistakenly substituted the length of a degree for a length of a minute because I was still thinking of degrees. (Long day.) Let me try again: 1 minute = 1/60 degree = 1/60 * 111 = about 2 kilometers (one nautical mile). Thus 0.001 minutes is about 2 meters. We could go further: 1 second = 1/60 degree = about 30 meters (this is handy to memorize), 0.1 second = 3 meters, and so on. One grad = about 100 kilometers and so on. One radian = about 57 degrees = about 6000 kilometers and so on. Did I leave out anyone's favorite angular measurement? :-) – whuber Jun 19 '14 at 22:00
  • @whuber Sorry for any confusion - my first comment here wasn't directed at you, we were typing at the same time. Asker has a comment that says "feel like this isn't right", and that is what I was responding to. My pinging you was about adding a similar chart as that I linked to your (great btw) answer at the other question. That way your answer there would also (explicity) cover decimal places of minutes and seconds, and not just degrees. – Chris W Jun 19 '14 at 22:32
  • Using DGPS correction (e.g. WAAS or EGNOS) the highest precision is about 1 m. But as mentioned before it depends on the satellite geometry (DOP), the number of visible satellites, multi-pass... – Zoltan Jan 23 '16 at 15:56

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