Open bar

I think this is generally good representation of what you'll need. One drink per person per hour is a pretty standard estimate, but you can alter the percent drinking beer vs. wine for your crowd. You should also consider who's serving. If you're hiring a bartender, they may have their own estimates they want you to use. If you're letting people self-serve or asking a family member or friend to do it, then you'll need to talk to them about how many servings you're trying to get out of each bottle of wine. A standard glass of wine is 5 oz-8oz, but when pouring for ourselves or for friends, or when you have someone who isn't a pro pouring, they tend to come out a little higher than that. You don't want them pouring heavy and then going through the bottles quicker than you intended.

I can't answer your question, but I have heard the idea that you should buy from a retailer that will let you return any unopened bottles. That might be a way to make sure you have enough to cover the night plus some, and then just return what doesn't get used.

Definitely agree with PP. My family is still drinking wine from my sister's wedding in 2018 because we weren't able to return anything. The online calculators are great. The other thing I suggest is hiring a bar tending company to serve the drinks because they cover the liability insurance required and they could also help give an idea of how much of each to provide.

Here is a great calculator to help with this. https://www.evite.com/pages/party/drink-calculator

You can put in the amount of people, the types of drinkers they are (light, average, heavy), the length of time, and the type of alcohol. It will calculate what you need .