I am going to make a 8'' sub woofer box at school for my car and l got everything down except the hole for the woofer. l need to know exactly how big it needs to be, what is the normal hole size for a 8'' sub?

please help!

here is the sub....http://sonicelectronix.com/item_142_Audiobahn+AW831T.html
NOTE* l do not have the woofer yet....so telling me to trace it would not work... also, the reason l wanna mount just a 8'' is because l have a hearing condition and cannot have too loud of speakers...but llove sub woofers!! The reason i'm not going for a single re8 or somthing really nice is because i'm really short on money and this woofer has great ratings for being so low priced.

turn the sub over and trace the rim. then measure the circle. measure the rim of the underneath of the speaker(from the basket to the end of the lip. multiply that times 2 and subtract from original circle. draw a circle with new measurement and that is the circle needed. cut hole and mount woofer. though l wouldnt ever mount an 8 even less an audiobahn.

usualy there is a half inch difference in the hole cut out and the size of the speaker..what l usualy do is center mark where the hole is going to be cut messure out from that distance which in your case would be 3 3/4 inchs use a protractor to do the rest .some times the speaker(if new) will come with a hole pattern in the box ..good luck on the project