Joined: Jan 2009
Posts: 44,338
Likes: 6,637
From: New York, NY, and High Falls, NY, USA
Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem
Your gear ratio is a RATIO of the size of the chainring with the size of the cog. The ultimate ratio depends on both, so without specifying the chainring size, the question is meaningless. Or maybe you're assuming a chainring size.
My tandem's drivetrain has 52/42/30 chainrings, and the cassette is 11-40.