Try this site. Scroll down to the bottom of the page for a chart of stopper sizes. Look for an "average diameter" that approximates the diameter of the opening in your bottle.
We have been saving Svedka vodka bottles for a long time and have quite a few. They are 1.75 liters and made of heavy glass so I thought they would work perfect.
I was wondering what size stopper to get for them and this will help me figure it out.