Grant Erwin writes:

For example if a compressor is rated to deliver 10 cfm into 90 psi
then it could equivalently be rated to deliver approximately 26 SCFM.
So beware of SCFM ratings unless you have the above equation handy!

(In case anyone is curious, I got the above equation from a Sylvania
Web page: http://www.sylvania.com/pmc/heaters/air/using.htm)

I believe this is incorrect. The "S" means standard temperature and
humidity of the free air. See Machinery's Handbook.

http://www.truetex.com/aircompressors.htm