How long do turtles (as in the sort of turtle one might have as a pet) live?

I think longevity would depend on the individual species, but I found this general information.

Researchers have recently discovered a turtle’s organs do not gradually break down or become less efficient over time, unlike most other animals. It was found that the liver, lungs and kidneys of a centenarian turtle are virtually indistinguishable from those of its immature counterpart. This has inspired genetic researchers to begin examining the turtle genome for longevity genes.

“Turtles don’t really die of old age,” Dr. Raxworthy said. In fact, if turtles didn’t get eaten, crushed by an automobile or fall prey to a disease, he said, they might just live indefinitely.

Galapagos Land Tortoise - 193 years
American Box Turtle - 123 years

Box turtles are usually gentle in temperment. Some individual turtles can adapt to captive conditions, but many do not. Though they are popular as pets, box turtles have special needs and are more difficult to maintain than many aquatic turtle species. Box turtles can live potentially long lives in the wild (40 to 100 years), but few captive turtles achieve such longevity.

Spotted Turtle survivorship and longevity estimates are among the highest values reported for any animal species, and females are significantly more long-lived than males. Minimum annual adult female survivorship is 96.5%, maximum longevity is 110 years, and age at maturity is 12 years. Minimum male survivorship is 94.2%, maximum longevity is 65 years, and age at maturity is 11 years.

For example, the standard American box turtle can live more than 125 years, a leopard tortoise has a life span of up to 100 years, and an Aldabran tortoise can live to be more than 200 years old!

The Greek Tortoise aka. Spur thighed (Testudo graeca) is known to live 57 years captive.
A close second would be the Egyptian tortoise (Testudo kleinmanni) though very small only 6 in. shell length with a 52 year longevity record
is likely to be your best bet for indoor living though adaquate lighting and nutrition are essential.

Turtles are renowned for their longevity and provided your pet remains healthy, may live for thirty to seventy-five years in your care.
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Below is a site that you may wish to read if you're going to have a turtle as a pet.

http://www.petturtle.com/Default.htm

Okay, that's all I needed to know. I can cross them off my list of potential pets! Yikes!!

Why do turtles live so much longer than us humans?