Nominally 50 long, however what a tank gets called is usually an over estimate on true volume. Measure inside dimensions in inches, multiply the three directions and divide by 231 to get true volume in gallons. If you would it would help me gather a data set on nominal and true volumes for standard tank sizes.
Yup. It gives a rough estimate on volume. Of course when you add substrate, decor and filtration, it subtracts and adds to that volume, as well. I have that exact same tank, myself.