I measured the windows, I measured the walls.
Before we moved to a new place 500 miles away, I measured nearly everything-- except the distance from the shower rod to the base of the tub.
A shower curtain liner certainly qualifies as one of those things you need on your first day in a new apartment. So I went to the store and took my chances. I bought a new shower curtain liner of the standard length.
Unfortunately, it was about three inches two short. Water from the shower blew the bottom of the liner up over the tub, soaking the bathroom floor.
My solution? A clear plastic tablecloth from the nearest dollar store.
The tablecloth was about a foot too long, but I simply folded over the top until the "liner" was of the desired length, and then I poked holes at the top for the hooks. Voila! An extra long shower curtain liner that's less than 2 bucks -- and is easily replaceable.