Formula For State Plane to Lat/Lon Conversion

[GeorgePorto]

Does anyone know where I can find the equation to put into Excel that will convert CT State Plane coordinates to Lat/Lon?  I know ways to programmatically do this using ArcGIS but have a scenario/workflow where we may need to do this from within Excel.  Thanks!

[DavidFrame]

Hey, I'm trying to do something similar. I'm srid 2237. NAD 83 state plane Florida west zone. survey ft. My projection doesn't have standard parallels. But I do have a "Scale_Factor". So, I'm not sure if I can use your stored procs without some changes?

[SeanO_Halloran]

I'm using a state plane zone that does not have values for Standard Parallel 1 & 2.  Do you use a value of 0 in these cases for the functions for calculating latitude and longitude?

[MelitaKennedy]

Hi Sean, 

The posted code is for Lambert conformal conic. It sounds like your zone (which one?) is using either transverse Mercator or Hotine oblique Mercator. Either of those projections would need to be implemented.

Melita

[SeanO_Halloran]

Thanks Melita.  I'm looking at Idaho East NAD 83 US foot zone 1100 which is Transverse Mercator.