Banners can be made in any size to suit your requirements. But . . .
If you are putting banners on commercial sites or banner exchanges, you will need them to be a standard size - see 10 Standard Sizes below. To promote some aspect of your business on your own site, you may find one of the non-standard sizes very useful because they can be tailor-made to fit into sidebars or vacant spaces on your pages. We also create Flash Banners, if that is what you need. Check out our Special price on Banner Sets.