88×31 was the original “button” size for webcomics.  This is a very acceptable size for link exchanges, and often the smallest. Many people will link with larger sizes now, but this was once the default size. Definitely have at least one banner of this size available, and preferably, more than one.

117×30 is the “button” size on Project Wonderful.  Most webcomickers do not link with this size. If you are seeking a link exchange with someone, check their links page first to see which size they prefer.  You SHOULD have this size available on your links page as it is slowly becoming more popular, but I think you will find many still prefer to link with 88×31.

125×125 is the  “square” size.  It is very rare to see anyone choose this size to link another comic with.  Not unheard of, but rare. You MAY want to have this size available on your links page.

160×600 is the “skyscraper” or “tower” size. This is for advertising purposes only. No one will link you with this size unless they are crazy (120×60 is the thin tower, going out of style).

200×40 is my personal favorite size for link banners. It is also the de facto size for link exchanges.   It’s small enough you can often fit 3 across a page, but large enough you can fit some art on there. If you remember my 4-article series about making banners, art together with words make the best banners, especially for comics. Definitely have at least one banner of this size available, and preferably, more than one.

234×60 is the Project Wonderful “half banner” size.  I find it an awkward size myself.  Most webcomickers do not link with this size. Have this for size for advertising for yourself, but don’t expect others to use it.

300×250 is the “rectangle” size. This is for advertising purposes only. No one will link you with this size unless they are crazy or owe you a favor big time.

468×60 is the traditional full banner size. You will be lucky to get a link exchange with this size, but it’s certainly not unheard of.  This is a size to have for many things, including top lists, comic updater sites, comic collective banner rotations, and more. Definitely have at least one banner of this size available, and preferably, more than one.

728×90 is the “leaderboard” size.  This is for advertising purposes only. No one will link you with this size unless they are crazy.

Other sizes: some comickers have created link banners of very odd sizes. This is not advisable. People don’t like their link exchange page to be horribly cluttered, which it will become if everyone wants a different size. Feel free to have other sizes available ALONGSIDE the acceptable sizes.

Etiquette for people seeking link exchanges: if you are asking for a link exchange with another comic, do exactly that FIRST: ask! Do not email someone with your banner already attached, or with a link to you banner/links page, or with a link to your OWN links page, where their banner is up.  It is very rude to 1) send attachments to people who don’t know you 2) assume they will link you and 3) try to pressure them into a reciprocal link by already putting up their link. I recommend asking if they would be willing to exchange banners with you, and if so, what size they would prefer.  Ball’s in their court, and they’ll get back to you if they’re interested. 90% of people will be interested, unless you’re making a totally horrible comic* and you’re asking a totally great, popular comic*.

*relative designations.

Etiquette for link/banner pages: preferably you should have SOMEWHERE on your links page your linking policy. For example, do you even accept link exchange queries? Some people don’t (ex, Earthsong)! Are there comics you won’t link (mature? violent? graphic?)? What banner sizes do you prefer, and where can you be reached for queries? If your linking banners are on a different page than you link exchanges, make sure the link is prominent.