Shock length question

I ordered a lift kit that came with shocks, and the shocks they sent are too short. They agreed to do an exchange for longer shocks. I just have a quick question..
when the jeep is sitting flat, how much more should the shock need to be able to expand?
like if (just for instance since i have not measured yet) sitting flat the shocks are 20 inches long from mount to mount, how much shock should be left?
should it expand to 22 inches? 25?

Im sure i overexplained that, but maybe someone understands.

 

only accurate way to measure shock lenght is to compress one corner as much as possible and take a measurement. that is the compressed length.

Next let that corner droop as much as possible that is the extended length. Subtract 1/2 to 1 inch from the compressed length. Add 1/2 to 1 inch to the extended length. That will keep the shocks from over extending or bottoming out.

 

I appreciate the info, never had to measure shocks before. ill get that to them and hopefully they'll get the new ones to me quickly.

 

Well it turns out that since it took me a while to install the kit i have gone past the thirty day return period. I did not measure the shocks to start with, so i guess its my fault. i did one side and just popped the shock on the mount when it opened up enough to go on. turns out they sent two different sizes, and somehow i grabbed the two longest ones first. so it took to the third tire for me to realize the shocks were wrong.
After emailing back and forth they just wont do anything about it. they did say they could get the right shocks for me, but no exchange or discount. I sent them an email back telling them to forgive me if i dont jump on that offer.
If you buy the economy lift kit from "carparts" on ebay make sure that you measure the shocks quickly or you might get to keep in your garage 4 shocks you cant use.

anyone wanna buy some shocks?