What canvas to use?

[Beatlemarta]

Hello!!
Thanks SO MUCH for this incredible site!
I converted an image to pattern, and I said I wanted it in 60x40 Cms. What thread count canvas do I use so that the image comes out in those exact dimensions? I never get it right. ehehehe. I'm afraid I'll buy 75 cms of canvas and only half the image will fit in.
Thanks so much!!
Much love from Portugal
Marta