# How precise are these coordinates? **URL:** \ **Category:** Factual Questions\ **Created:** [March 30, 2024, 10:24pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621 "2024-03-30T22:24:58Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [March 30, 2024, 10:24pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/1 "2024-03-30T22:24:58Z")
I do a lot of photo identification on [Vintageaerial.com](http://Vintageaerial.com). When I pin the location of a photo I describe the location in simple terms like, “north side of Cecil St just west of Adams Rd.” Occasionally I will use an actual address but Google addresses are not always reliable especially in rural areas. Other VA users are fond of including the coordinates. One particular user gives an insanely precise set of longitude and latitude, like 41.644431067887815, -81.16733213096677 Fer chissakes Google Maps only lists coordinates to 6 decimal places. What precision is this guy claiming? And how would you get them? ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 30, 2024, 10:36pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/2 "2024-03-30T22:36:46Z")
He’s “getting” that precision from his ass if that is what he truly claims, otherwise it just looks like he printed out double-precision floating point numbers, so it could be a user-interface bug. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [March 30, 2024, 10:50pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/3 "2024-03-30T22:50:38Z")
> [@mixdenny](#): > > Fer chissakes Google Maps only lists coordinates to 6 decimal places. You only need 5 digits (after the decimal) for about 1-meter precision. He’s claiming sub-nanometer precision there… ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [March 30, 2024, 10:56pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/4 "2024-03-30T22:56:55Z")
It could be the output of a conversion from another co-ordinate system (or another lat-long format such as ddd mm.mmm or ddd mm ss). They enter a set of co-ordinates with (say) 7 sig figs but the interface calculates and outputs the result with dozens of sig figs, which the person copies and pastes. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [March 31, 2024, 12:20am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/5 "2024-03-31T00:20:25Z")
He’s giving the latitude in degrees to 15 digits after the decimal point. One degree of latitude is about 70 miles. 10-15 degrees of latitude is 0.11 nanometers, about the diameter of a hydrogen atom. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 31, 2024, 12:24am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/6 "2024-03-31T00:24:25Z")
> [@mixdenny](#): > > One particular user gives an insanely precise set of longitude and latitude, like > > 41.644431067887815, -81.16733213096677 > > Fer chissakes Google Maps only lists coordinates to 6 decimal places. What precision is this guy claiming? And how would you get them? The geodetic precision at six decimal places is approximately 0.11 meters (4.3 inches) in latitude, and about 0.08 meters (3.2 inches) in latitude at that azimuth. While it is possible to get more precise measurements using very sophisticated methods, these are really only used to measure tectonic movement and in suborbital ballistic trajectories. This is obviously not necessary for locating a landmark and is likely just the result of mindlessly copying GPS coordinates from a receiver that doesn’t truncate or making a conversion without carrying through the correct significant figures. Stranger ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [March 31, 2024, 12:24am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/7 "2024-03-31T00:24:26Z")
> [@markn\_1](#): > > He’s giving the latitude in degrees to 15 digits after the decimal point Dang it. Now we’ll never know his precise momentum. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [March 31, 2024, 12:29am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/8 "2024-03-31T00:29:08Z")
Some of the archery flight shooting enthusiasts use coordinates to within 1". Most of us don’t trust the accuracy quite yet. ---
**Author:** ![Kedikat](https://avatars.discourse-cdn.com/v4/letter/k/ed655f/32.png) [@Kedikat](https://boards.straightdope.com/u/Kedikat)\ **Post date:** [March 31, 2024, 12:35am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/9 "2024-03-31T00:35:47Z")
I use licensed positioning assist systems and only get a usually guaranteed 10 cm accuracy. But if I let them survey in for some time it gets more precise than that. Using RTK can let the rover get very precise position as well. But the numbers sited in the post are as others rightly mentioned, software induced fantasy. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [March 31, 2024, 1:03am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/10 "2024-03-31T01:03:59Z")
> [@Folly](#): > > > [@markn\_1](#): > > > > He’s giving the latitude in degrees to 15 digits after the decimal point > > Dang it. Now we’ll never know his precise momentum. You win the thread by a mile. Correction … 1.000000000000000000001 miles. ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [March 31, 2024, 5:59pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/11 "2024-03-31T17:59:39Z")
> [@HoneyBadgerDC](#): > > Some of the archery flight shooting enthusiasts use coordinates to within 1". Most of us don’t trust the accuracy quite yet. One-centimeter accuracy (about a half an inch) is standard in the cartography and land surveying professions. ---
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [March 31, 2024, 6:17pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/12 "2024-03-31T18:17:58Z")
> [@chappachula](#): > > One-centimeter accuracy (about a half an inch) is standard in the cartography and land surveying professions. I should have been more specific, we do trust the surveying equipment, we don’t yet trust the cell phone measuring devices. ---
**Author:** ![Banksiaman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/banksiaman/32/3334_2.png) [@Banksiaman](https://boards.straightdope.com/u/Banksiaman)\ **Post date:** [March 31, 2024, 9:05pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/13 "2024-03-31T21:05:35Z")
The other issue that arises at this scale is what sort of point is he marking? Surveyors use very clearly designed trig station and target marks so that you know the measurement point is at the exact and unambiguous intersection point. If you are, for example describing the location of a road, its going to be 3 metres wide so your last 10 digits imply accuracy that simply isn’t there. Similarly, whenever a pirate tells me that they have a map where X be marking the treasure spot, I am always careful to correct them that the X on their map is usually covering some hundreds of square metres, so not just marking their spot, but lots of superfluous ground, and that they should obtain the services of a registered land surveyor. Its money well spent in that situation. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [April 1, 2024, 11:32am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/14 "2024-04-01T11:32:30Z")
> **[Coordinate Precision](https://xkcd.com/2170/)** > > 40 digits: You are optimistic about our understanding of the nature of distance itself. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 1, 2024, 12:22pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/15 "2024-04-01T12:22:11Z")
> [@Banksiaman](#): > > I am always careful to correct them that the X on their map is usually covering some hundreds of square metres, so not just marking their spot, but lots of superfluous ground, and that they should obtain the services of a registered land surveyor. Its money well spent in that situation And since the pirates don’t want the land surveyor to come back later with his knowledge of the exact location, and since furthermore dead men tell no tales, the payment part of the transaction becomes completely optional. Pirating is such fun! ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 1, 2024, 2:20pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/16 "2024-04-01T14:20:04Z")
> [@Banksiaman](#): > > Similarly, whenever a pirate tells me that they have a map where X be marking the treasure spot, I am always careful to correct them that the X on their map is usually covering some hundreds of square metres, so not just marking their spot, but lots of superfluous ground, and that they should obtain the services of a registered land surveyor. Its money well spent in that situation. Oh, yeah, that happens to me all the time, too. ---
**Author:** ![Timz](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@Timz](https://boards.straightdope.com/u/Timz)\ **Post date:** [July 16, 2025, 11:59pm UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/17 "2025-07-16T23:59:54Z")
“Google Maps only lists coordinates to 6 decimal places” You probably noticed they’re down to five digits now. But if you click on that five-digit lat-lon, Google copies a more “precise” lat-lon to the clipboard – 14 digits I think it is. And six or those digits are useful. If you want details, speak up. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [July 17, 2025, 5:33am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/18 "2025-07-17T05:33:48Z")
> [@Timz](#): > > “Google Maps only lists coordinates to 6 decimal places” > > You probably noticed they’re down to five digits now. Where are these digits shown? I don’t log into Google, so perhaps they only show to people who do. At any rate, you can get 7-digit lats and longs from the url. That many digits is more than adequate for my purposes. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 17, 2025, 11:08am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/19 "2025-07-17T11:08:24Z")
> [@dtilque](#): > > Where are these digits shown? Right-click anywhere on the map. The top entry in the pop-up is the lat/long of where you clicked to 5 decimal places. If you choose the second option on the pop-up, “share this location”, the next pop-up shows the coords to 6 decimal places. If you save that link and open it in a fresh tab, it displays the result to 6 decimal places and also to the tenth of an arcsecond. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [July 17, 2025, 11:37am UTC](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621/20 "2025-07-17T11:37:44Z")
Not to be farting in church here, but, there actually is a small benefit to including multiple insignificant figures – as long as we’re clear what the expected accuracy actually is. Those extra otherwise meaningless digits form a kind of fingerprint that follows the numbers wherever they are all copied. Later, somebody wondering where the measurement came from may be able to trace it to earlier references by matching all those digits. Just sayin… [Next page](https://boards.straightdope.com/t/how-precise-are-these-coordinates/999621.md?page=2)