How to determine case fan size? (80/92/120mm)?

[WAZ]

I may sound dumb here, but I can't seem to figure out what size case fan I need. It's just the regular exhaust fan at the back of the case. The screw holes measure 11 cm (110 mm) across. Is fan size measured by the height/width of its mounting case? That's the best I can think of -- if the 120mm case fans are 120mm across TOTAL, then if the holes are 5mm in on each side, it would make sense (its mounting holes would then be 110mm apart). That's the best I can think of, but I don't want to order one and have it not fit. Any help would be great.

Thanks in advance-
WAZ

 

[Howard]

A fan is measured by it's grand total width and height, not the distance between the screw holes. Obviously an 80mm or a 92mm won't get in there (smaller than the space between the screw holes).

120mm for that spot. Measure the mounting case with a ruler.

 

[corkyg]

The standard size with pre-drilled holes in any case I have ever worked on is 80 mm.

 

[corkyg]

The standard size with pre-drilled holes in any case I have ever worked on is 80 mm. In English terms, that is a 3-inch fan.