Harold Ramis says ten. (The screenwriter, Danny Rubin, invites you to pony up to find out what he thinks.) These folks say eight years, eight months, and sixteen days. My favorite estimate comes from this brilliant breakdown, which gives it as 12,403 days of Sonny and Cher and sweet vermouth on the rocks with a twist, or almost 34 years. Poor Phil. He really earned that happy ending.

—Emily Gordon