Ok so i think i'ved decided on a breed...?

i'm pretty sure i'm gonna get a chihuahua... although this may change knowing how indecisive i am. its either a chihuahua or a dachshund. right now im getting everying ready. im looking for a crate. i will be crate training my dog.. BUT THE THING IS, I DONT KNOW WHAT SIZE CRATE TO GET!!! i dont want the crate to be too big..or else the dog will use the bathroom in it. just big enough for it to be comfortable. is this 2 big for a crate for a chihuahua? (24 x 18 x 21)