Although the 1 in 60 rule works, life is far too short to work that out for an ILS.
Stick with Pegasus77's plan, or for round numbers, use 300 ft nautical mile.
2,000 ft = just under 7nm
3,000 ft = 10 nm
4,000 ft = just over 13 nm
5,000 ft = just under 17 nm
etc ad nauseam