this may seem like a dumb question, but i guess i dont get it.

I poped my tire the other day, and i went to buy a new tire, and innertube, because both were shot. I found the right tire, but for some reason i couldnt find the right inner tube. The tire is a 700 27. i the inner tube suppost to be 27'' or 26''. i would assume a 26, being that the tire goes around the inner tube, so it would need to be smaller. Im not sure, and this is probebl a noobish question.