Will I need an adapter?

I just ordered a Nikon 55-300 lens for my Canon T2i and I'm not sure if the lens will fit the body of the camera. Will it need an adapter? And if so, what would be the best and cheapest one to get?

You will need an adapter. See my link to Ken Rockwell below. If you purchase an adapter, please do so through his site to support his business.

Of course you will need an adapter but the thought of not getting the right one which will work flawlessly with your camera in the first place just baffles me.

http://www.bhphotovideo.com/...rtclk=sort

For practical purposes, if you already have the 18-55mm kit lens, you will not miss the 55-80mm gap.

Why on earth did you do that?
There may well be an adaptor to fit a Nikon lens to a Canon body but it will have no auto focus and no auto exposure. Chances are you will lose infinity focus too!

Cancel your order and get a Canon lens - either the EF-S 55-250 IS F/4-5.6 or if you have the cash then the EF 70-300 IS USM F/4-5.6. Do NOT go for the Canon 75-300!

The 55-250 is the bargain of the century and you will not notice the slight drop from 300 to 250 at the long end.

Why on earth would you be foolish enough to order a Nikon lens when you own a Canon DSLR?

Send it back and order a comparable Canon lens for your Canon DSLR.

Although there are adapters made to allow use of a Nikon lens on your Canon DSLR there will be NO auto focus and you'll have to use stop-down metering - if the camera will even meter. If the Nikon lens is a G lens then it will have no aperture ring on the lens and there will be no way to control the aperture. A Nikon lens on your Canon DSLR may prove to be as useless as a three-legged horse in the Kentucky Derby.

Always buy lenses made for your camera. Always.

Send the Nikon lens back and order a Canon lens for your Canon DSLR.