Tobe- Marilyn is right with 2000 being an average mile. The pedometer needs to be adjusted to your stride. Most of them will tell you how to calculate your stride (basically your step from heel to heel. Most will have you walk about 10 steps then measure and divide by 10). If there isn't an adjustment I would say it isn't worth using. They aren't very expensive to get a decent one. Go to WalMart in the pharmacy section and look at Omron brand. They seem to have a good reputation for accuracy. I like using mine but I walk so much in the water that I have to guestimate that about 30 minutes of water walking is about 1 mile.
I bought last year when i started my journey from QVC. The stride never made sense to me. I mean i knew how to calculate it and i did it, but would walk for an hour, and it would show i only did like 2300 steps and 1/2 mile.... so its sitting in the junk drawer.