I agree with Steve, Etsy should have a calculator, it does hard sometimes.
But the way I do it..... if its a small canvas under 8x10"size its usually about $4 if that can fit in a small envelop or little box (keep in mind about the weight) What I learn about international shipping that all about the weight and a dimentions of the box, the bigger then more expensive.
Also, always use First Class International Parcel for foreign packages, does much better price, like from US to Australia on First Class INt Parcel can be $18 and with Priority Mail would be $64 the same box, huge difference!
And, canvases 8x10" I ship in a boxes to be safer, and cost usually $8-$12.
Size 11x14" usually $10-$17 around US.
Even glass framed art can cost about $8-15
Well, I hope it will help a little.
Good Luck!
Natalia Denger Original Art