Or you just get a computer-in-your-pocket calculator to do the conversions for you *pats TI-85*.
It's a 45 gallon tall. I have one in the store set up as a salt water kit, and I remember that it takes a 36" long hood. I like them because they have nice wide viewing space but I don't like them because they don't have any width to them. Seems like a whole lot of tanks are like that. If you want nice wide viewing, you get taller narrow tanks that are hard to decorate in. At least, I find it hard to decorate, I don't like a whole lot of empty tank up top.
But if you want width and surface area to turn around in, you get this squat little viewing space. Compare a twenty gallon tall to a twenty gallon long and you'll see what I mean.
Have fun with your tank.
~~Colesea