# Converting XY to lat and lng?

I'm new to GIS, and I have some tasks that have to work with lat and lng values. The problem I have is this. I received some Excel files from a data source that supposed to contains some buildings' lat and lng in area A, and what I got was just have x and y (I don't know what does it mean). I know there are several different values like map xy, so I think those are one of the Geographic coordinate system that I don't know. I have to figure it out what is it and have to convert it into lat and lng that you can use it in Google Maps. I wonder if it is possible?

So, the numbers very strange, the area A supposed to have like lat 35.XXXXX and lng 127.XXXXX and what I got was something like x: 12834.6278 and y:3551.5214. At first I thought that those are map x and map y, because one time data source gave me that kinds of numbers and I had to find tool to convert it into lat and lng. However when I use that tool and put numbers I got into Google Maps, it pointed area where not even close to area A.

those are sample data

``````     x     |      y
12834.6278 |  3551.5214
12834.6689 |  3551.5184
12834.8509 |  3551.4267
12834.8004 |  3551.4605
``````

and this is lat and lng inside of area A, the format of expected numbers.

``````     x     |      y
35.856770  |  128.576365
35.860748  |  128.570098
``````
• Maybe play with projfinder.com ? – markusN May 13 '17 at 0:59
• 51/60 approx 0.85 thing using your language – FelixIP May 13 '17 at 1:37
• Welcome to GIS SE! As a new user please take the tour to learn about our focused Q&A format. – Midavalo May 13 '17 at 1:59

Just trying to follow @FelixIP's insightful comment;

Along with the original x and y, add two columns for lat and lon. (as A=x, B=y, C=lat, D=lon below.) And enter formula into C and D cells as follows, which will give the output (value in red) also in the above image.

``````A2: x
B2: y
C2: =LEFT(B2,2) + (B2-(LEFT(B2,2)*100))/60
D2: =LEFT(A2,3) + (A2-(LEFT(A2,3)*100))/60
``````

This is because of the different convention in a graph (paper based map) and grid (globe based map). In a graph, the x-axis increased to right and y-axis along an upward direction. value of X is written first followed by Y i.e. first right then up. But in the grid system, lat increases in upward direction and lng in right direction. This is similar to having YX graph, i.e first you have to go up then right. If this is not understood the points do not appear where they should appear and they are also rotated.

The data you have is in lnglat format instead of latlng, i.e. x in lng and y is lat