Rep Power: 179

So I did a compression test on my car today just for the heck of it and well i got 120 psi across all four cylinders. I wanted to know if this is a good number for our cars. I feel like its too low. But the car runs perfectly fine. Btw its a 2005 Honda Civic ex d17a2 68k miles.

 
Rep Power: 518

I'd call it very low, but I'd venture to guess you didn't use the same methods I use.
Also, many variables come into play.

Using my methods and equipment, I expect over 180 PSI, hopefully in the 200-220 range. It is also rare that I do a compression test for no reason.

 
Rep Power: 186

Yeah you did something wrong or you have some serious issues being 68K young. Last time I did mine was after I replaced my head gasket and I had 210 psi across all four cylinders. Mine is a 2002 ex with 88K on it.

 
Rep Power: 179

I used a compression tester from O'Reilly that my friend rented and I did it with the engine cold. I don't know if that makes a difference or not.

 
Rep Power: 518

Engine at operating temp
Remove ALL sparkplugs.
Use a prop to mash the gas pedal to the floor.
Strong battery. Good starter. Good cranking RPM. (Slow cranking speed will kill your readings.)

Screw the gauge into first hole.
Have helper crank the engine.
Watch the amount of rise on each of the first few strokes.
Mental note them.
Keep cranking until the tester quits climbing.
Crank some more to make sure it is done climbing.
Probably 10 "hits" or more.
Record the results.

Next cylinder.
Same process.
Repeat until done.