That depends on the mechanical and electrical specifications of the driver, otherwise known as Thiel-Small parameters. Car audio driver manufacturers rarely provide these measurements. Most home audio driver manufacturers will provide them. Once you have these measurements you can use a box software to perform the volume calculation for you. The minimal parameters needed are Fs, Vas, Qms, Qes, and Xmax.
I need the box spesifications for the pioneer TSW305C/DVC 12" subwoofer
Google is your friend. top mount depth 5-5/8" sealed box volume 1.2 cubic feet ported box volume 1.3 cubic feet As I stated earlier, the car sub manufacturers don't provide T/S parameters so all you can do is go by their recommended enclosure unless you want to measure the driver yourself.
Timn8ter - there are many DIY SpeakerBuilder magazines available, some have blue prints for simple to complex wood-working projects, crossover projects, car installs and the like. People post their homemade systems in the magazine. Any larger magazine store will have some of these.
TIMn8thr - thanks for the e-mail; I hadn't see your nice website in fact. I was just trying to offer potential resources for speaker building as I remember making a pair during my teen years; they were hideous):
i need some measurements for 3 solobaric L512 they are going in a two door ford explorer
how to build a speaker for 150W amplifier
what would be the measurement for the dash board and to connect the speaker inside the box and what would be the best design of speaker for 150W amplifier
john334, In almost every case, car subwoofer driver manufacturers do not provide specs for proper enclosure design. The best you can usually do is just follow their recommendations for enclosure size. I have no idea how to answer that last question.