Lightbulb Length Question

[Iodizedfate]

I received some japanese fluorescent light fixtures from a friend. They run no problem off the american outlets (similar voltage I assume). I was looking to see how much it would cost to replace the bulbs. I know that they are T8 bulbs and are 20 watts but when I measure them (from pin-to-pin) they come out to 23.5 inches and the fixtures are 24 inches. Would that mean I get 24 inch bulbs and they would fit? Or would I need to see about ordering bulbs from japan?

Lights : 2 - kotobuki twinlight 24inch 20watt X2

Big question is are 24 inch bulbs exactly 24 inches or could they be slightly smaller? I don't want to spend money on bulbs that wont fit.

 

[Iodizedfate]

If anyone finds this I found my answer. I went to the LFS and he pulled out a 24" bulb and measured it and it came out to about 23.5" which is the same thing that I got for my Japanese fixture. So I'm going to assume American bulbs and japanese bulbs are that same for length at least.