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When using coordinates in decimal degrees, how many decimal points actually make sense?

For example, say one is producing a table of locations of base camps in a report, there's no point in displaying a number like 62.946916, -135.018639 when 62.95, -135.02 is sufficient. On the other hand when giving someone a waypoint for GPS navigation 62.947, -135.019 is more warranted (manually keyed in, why type 6 digits when 3 will do?), while for locating a geocache 4 positions is desired, and 6+ for a survey stake.

In other words, what is the easiest way to determine for any given purpose how many decimal places should be displayed?

There are technical answers at Algorithm for offsetting a latitude/longitude by some amount of meters, but they're not readily adaptable to a quick reference handbook style of usage. I'm looking for a handy chart to refer to like "the nth decimal place is X distance in ground units (at Y latitude)", or "the nth decimal place is X distance in ground units (at ___ major city/landmark)".

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matt wilkie
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    The 111,111 number from the referenced doc will get you in the right neightborhood (though it's really 60 * 1852m = 111,120m per degree of subtended arc). Using it, 6 places is ~10cm, 5 places is ~1m, and 4 places is ~10m (all at the equator) – Vince Jun 02 '14 at 18:28
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    ...not sure why I couldn't find How to measure the accuracy of latitude and longitude? when I posted this question...{shrug} It is very close to a duplicate, but not entirely because the answers there only deal with the equator. Ideally an answer would be added to the other Q to flesh out the latitudinal differences. – matt wilkie Jun 02 '14 at 19:01
  • Good rule of thumb: five decimal places is one meter. So you might want to specify the difference of adjacent tents to the nearest meter -- five decimal places. If you are driving somewhere, knowing a business location to within 10m sounds pretty accurate, so four decimal places suits you. If you are describing the location of a town -- well if it is 1km across or more, then two significant digits are plenty. – Dan H Dec 09 '17 at 16:56

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