If you always work with GPS coordinates, so no way except to have coordinates converter on your IPhone!
LatLong is a simple powerful app which support you to convert the GPS coordinates converter from decimal to degrees and vise versa.
it also enable you to show the point you convert on MAP with full zooming in and out
convert from Decimal 2 degrees
convert from degrees 2 decimal
show the point on map
Prevent you from writing any un-logic letter/ number in fields of input
Can copy the output coordinates and paste in any other app.
Note: you have to input the coordinates using English numbers