You will find vendors promising two, three or even five times more calls with a power dialer. Published figures for calls per hour across dialer types are inconsistent from one source to the next (compare Regal and Aloware), so we would rather show you how to work it out for your own team.
Every call attempt is made of four parts: finding and dialing the number, ringing, talking, and wrap-up. A power dialer shrinks the first part to a countdown and makes wrap-up faster with a disposition screen. It does nothing to ring time or talk time. That is why the gain is largest for teams with short calls, low connect rates and lots of attempts per day, and smallest for teams having long consultative conversations.
An illustrative example, not a benchmark: assume a telecaller spends about 30 seconds finding and dialing each number by hand, and the dialer cuts that to a 5-second countdown. Across 80 attempts a day, that frees up roughly 33 minutes. Plug in your own numbers from a day of manual calling and you will have a far more useful estimate than any vendor headline.