The going average hourly rate for a mechanic ranges from $80 to $100 an hour. After analyzing a bill that could also include expensive parts, many auto repair shop customers are left scratching their heads and wondering if they are being ripped off.

The more you understand how a repair shop breaks down and calculates their labor charges, the better chance you have of making sure you are getting a fair shake.

Why does a mechanic cost $100 per hour? How much of that does the mechanic take home? How is that figure determined?

How Are Labor Charges Determined?

The rate of $80 to $100 an hour is based off of several national labor guides that are published annually. The guides survey mechanics all around the country to come up with figures and average times to do repairs.

"Let's say you were going to go in and get a water pump job done. They're going to say, 'OK, that job takes two and half hours and the parts are 60 bucks,'" said Mark Larsen, a franchise training manager for Car X. "Well, where that two and a half hours comes from is your car and what an average tech with a good set of tools takes to do that job."

So, if a mechanic tells you the average time to replace your water pump is four hours, and you are suspicious of that, making a few phone calls to other shops to ask them what they estimate for time is a good, quick, easy way to double check.

But if a mechanic runs into a problem and it is going to take longer than what was originally expected, there could be extra labor charges if the problem is a result of poor maintenance.

"Let's say you have an engine you haven't maintained at all," said Larsen. "The coolant is rusted, and I go down to change your water pump and all the bolts are rusted, half the bolt's gone, and the coolant is so bad. I go to take your water pump off and two of your bolts break off, well guess what? Its now on you and whatever extra time it takes, that's extra."

Dealerships tend to charge more for labor, closer to the $100 per hour range, than independents.

"Its kind of a market-driven thing. Chicago might be higher than others. It's an average thing, based upon what's going on," said Larsen. "It seems like the dealers vs. the independents usually charge a little more. They base it on the fact that their guys are factory trained, and they've got all the special tools that not everybody's got."

Where Do Labor Charges Go?

How much of the hourly rate goes into the mechanics pocket can vary drastically. Some mechanics get paid straight by the hour, some make commission, and some get paid by how many labor hours they charge in the week.

"When I worked as a tech, I got paid and hourly rate, and that was based upon how much work I put out, not how many hours I worked," said Larsen. "If I put out 48 hours of work for the week, then I got paid 48 hours."

To the average customer, a charge of $100 an hour can seem very high, but you must take into consideration the cost of running a repair shop.

"Well, you're looking at a whole lot of things," said Larsen. "From the owner's perspective, he's paying salary, he's paying benefits, he's paying workman's comp, he's paying unemployment. You got all that into it. You got the building, the lights, the tools, the training, all that goes into it."

Also, the cost of becoming a mechanic can be expensive. Mechanics must put themselves through school and the common practice in the auto industry is for mechanics to supply their own set of tools.

"Every mechanic's got at least $25,000 in tools that they own. They've had to pay for them themselves," said Larsen.