maximum print sizes.

[JMBriggs]

I have a Canon t1i and want to order the largest canvas possible without losing image quality. Can anyone help me with this?

 

[KmH]

Do you realise how big the largest canvas possible can be, and how much it would cost?

Your T1i makes 4752 x 3168 pixel images. At 100 PPI that would be a 47.52 inch x 31.68 inch photo. At 200 PPI it would be 1/2 that size - 23.76" x 15.84".

If you want more PPI and/or a larger image the image resolution will have to be increased. That increase is done by software extrapolating pixels that didn't actually exist.

 

[MLeeK]

The maximum image size depends upon how closely you will be viewing the image. If you are viewing at point blank range, you'd want to be sure you are at about 240ppi. However, if you are viewing from a reasonable distance? You could print a billboard.
You don't view a billboard from touching distance, you view it from an appropriate distance.
So, now what size do you want to print; where will it hang and how will it be viewed?