How much wine should I buy for a wedding?

The question: What’s the right number of bottles to buy for a wedding with 80 guests?
The answer: Are these my friends and family or yours? 
The answer: Are these my friends and family or yours? The answer depends.

You, of course, are the best judge of your crowd’s thirst. But I can offer a guideline. While not intended to encourage overconsumption, of course, especially where driving is involved, the absolute minimum is half a bottle a person – not including bubbly for a toast or hard liquor at the bar. The night will be long and joyous, and there will be food and dancing. There will be abstainers in the mix, but others will imbibe more than their share (if my experience as a wedding guest is an indication).

My personal strategy would be to spring for at least a bottle for each adult, more likely a bottle and a half. I’m sorry if that sounds scandalous. Just be sure to make an announcement that no one should overimbibe without a designated driver. You can usually return what you don’t use. Alternatively, if the reception is held in an unlicensed establishment, such as a private garden, you can keep the leftovers and relive the festive day over and over again with the same wines.

I like weddings, and there is no excuse (except poverty) for running out of booze on a great evening such as this. As with flattery for the bride, it’s better to err on the side of too much than too little.
http://www.theglobeandmail.com/life/food-and-wine/wine/ask-a-wine-expert/how-much-wine-should-i-buy-for-a-wedding/article2447443/