The events invitation site Evite is adding features for planning parties, giving hosts such tools as a drink calculator to figure out how much alcohol to buy based on whether guests are light or heavy drinkers.

Hosts enter the duration of the party and the number of light, average and heavy drinkers attending. They also specify whether they'll serve beer, wine, liquor or any combination. The tool then calculates the number of cases or bottles needed.

A chart is provided to substitute alcohol with soda or juice, but amounts must be manually calculated.

Another tool lets hosts automatically set budgets for food, drinks, decorations and entertainment, based on the number of guests, duration and the party type — baby showers and birthdays are among the options.

Evite, traditionally a site where guests can RSVP and see who else might be showing up, is now also providing recipes, wine-pairing guides and checklists as part of a redesigned site launched this week.