Convert X, Y into Latitude,Longitude with unknown system

Question

I have a set of X, Y values that indicate some locations in Hong Kong. But I am not able to convert the X/Y into latitude/longitude since the coordinate system is unknown. Is there any way I can fit the X/Y value into many Geographic information systems to find out which system the data provider is using?

The data I have:

X       Y
840787  816064
839740  819091
839291  819498
840383  816178
835702  818880
833502  816629
837048  815708
838910  823019

Answer 1

Your coordinates seem to be in EPSG:2326 (Hong Kong 1980 Grid System).

A great way to search for coordinate systems is to go to epsg.io, there you can search registered coordinate systems by country, by code, etc. and get a preview of the coordinates with an interactive map, as well as the definition of the coordinate system.