How long they last depends on what you drive and how you drive.
Some vehicles go through brakes faster than others.
Repeated hard stops wear brake pads quickly. Towing a trailer or driving on mountain roads can mean more-frequent brake jobs. The front pads generally last anywhere from 15,000 miles on up, while the rears often last twice that long. That's because the front brakes are designed to do about 80 percent or more of the braking to compensate for the car's weight being transferred toward the front wheels when you brake. Many states don't have a periodic safety-inspection program that covers all cars and that includes the brakes, so it's up to you to make sure your brakes are safe.