Lat lon how many decimal places

Converting the distance in metres between two coordinates provides a way to evaluate the precision of the coordinates on the earths surface. This can be done using basic trigonometry and the shape of the earth as illustrated in the image below. The shape of the earth can be represented as an ellipsoid. The semi-major axis approximates the distance from the earths centroid to the earths surface at the equator x.

Using the trigonometric equation below, distances can be calculated at the surface of the ellipsoid at various decimal degrees such as 0. Using 2 or 3 decimal places might be wise if privacy is a concern when sharing coordinates with others. Keeping 6 or more decimal places would be useful for the most precise GIS applications with input from land surveying. The distances change very little across the entire earths surface test this using the above equation if you are curious. You are commenting using your WordPress.

You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Submit Expert Request. When it comes to GPS coordinates, the more decimal places, the better.

Using four 4 decimal places, you get closer, now only 10 to 15 feet away. Finally, using six 6 decimal places, you get to the exact point! Send Message. Share This Post :. Find A Blog Post. Recent Blog Posts. Connect With Us. Do you have a question for us? We're here to help! Contact Us Today. Areas of Expertise. The last blog post came on the heels of the national open elevation release of England with insane vertical resolution. Longitude and latitude coordinates are stored with 15 decimal digits right of the decimal points.

But what do 15 decimal digits mean for longitude and latitude coordinates? I took the second coordinate pair [ Before conversion we quantize these numbers to have 5 through 15 decimal digits and then record the absolute difference to the coordinate pair that uses the most digits.

Number o decimal digits for longitude and latitude coordinate and absolute difference in projected position. The table above shows that — at least for this particular longitude and latitude coordinate pair located in Germany — that 7 digits are sufficient to store coordinates with centimeter [cm] accuracy and that 8 digits are enough to store coordinates with millimeter [mm] accuracy.

Any additional digit right of the decimal point will only be necessary when we need micrometer [um] or nanometer [nm] accuracy, which is very unlikely to be the case in most geospatial applications. This means we could remove the 7 or 8 right most digits of each number from the screenshot that was tweeted and make this GeoJSON file even smaller, faster, and easier to store, transmit, open, and read.

After this post was tweeted there was a follow-up tweet suggesting to have a look at this site for a more detailed analysis of what accuracy each digit in a longitude and latitude coordinate can store.

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