Ever wonder how to figure out how much wine to buy for a dinner party? Try out this calculator for your next party. I find they are useful for larger parties, but not a much for smaller parties. I would generally do one bottle of wine per person, with 40% being white and 60% red. In the winter up the red percentage and up the white percentage in the summer. If you’re having more than four people large format bottles, magnums and larger, can be a fun option.