Title pretty much says it all. About how many sets of pads do you get out of a single set of rotors? I've heard some people tell me it's 1:1 but that seems excessive. Currently I'm on my second set and am wondering if I need to swap the rotors with the next pad change...

 

There's no ratio because everyone drives and takes care of their equipment differently. If you let your pads go too long you'll damage the rotors on the first set. If you replace them before they damage the rotors you'll certainly get two, or more, sets of pads out of your rotors. I don't use the brakes so my brakes last forever. Other's speed up to every stop and slam on the brakes so they go through pads 4 times faster than I will. Just replace them when your dealership or knowledgable mechanic says they need to be replaced.

 

it really depends of Use of the Car and Style of Driving.

In my Case my Brake Light is on with my Second Set of Pads and Orginal Rotors at 151k

Rotors are Done

So for me 2:1

 

Main thing is to look for is signs of wear on the rotor and minimum thickness. Mainly you need to look for cracking connecting any of the holes where the rotor is crossdrilled. Minimum thickness is stamped on the rotor hat, but can be difficult to read. I rubbed some chalk on my rotor to snap a picture for demonstration purposes

You can make out where it says "Min. TH. 32 mm" This indicates that the rotors should be wider than 32mm for a new set of pads. Each of the cars is different for minimum thickness so get a decent digital caliper, some chalk and check yours out.

Breaks are one area you do not want to make any mistakes, so if your are unsure or hesitant take it to a pro! The pads are best replaced before they get too low. This will save you money on damaged rotors, and eliminate the need to replace the electronic wear sensors.

 

FWIW, I just performed the first pad changeout on my car. Based on pad and rotor wear (I mic'd the rotors), I estimate I will go through 2 pairs of "stock" pads between rotor changes. I do plan to monitor rotor wear every year (about 8K miles for me) to be sure they remain above minimum thickness and exhibit no cracking.

Rotor wear will be highly dependent on the type of pad you're using, as well as driving style as others have mentioned. If in doubt at all, a set of micrometers and a few minutes of your time are all that you'll need to know for sure.