Once the bride and groom have said "I do," wedding guests look forward to an evening of food and drink. Calculating the amount of alcohol needed to ensure a sufficient supply throughout the reception is a challenging proposition. Purchasing too much can put a big dent in the budget, but running out during the festivities may make you look cheap.
Finalise the reception logistics
Determine the number of people expected to attend the wedding reception before embarking on any calculations. Include the bridal party in the final count, but omit any wedding guests under the age of 18, the legal drinking age in the UK, and any guests who you know do not drink alcohol.
Assess the overall demographics of the attendees. In a demographically diverse group, expect roughly 50 per cent beer consumers, 30 per cent wine drinkers and 20 per cent who prefer cocktails. If your guests are predominantly young men, expect a higher beer consumption. A predominantly female guest list may consume more wine and wine coolers.
Finalise the wedding reception itinerary, particularly the duration of pre-dinner cocktails and post-dinner dancing, and list the type of drinks you will serve during each portion of the reception. Some people prefer an open bar serving beer, wine and spirits throughout the entire reception, while others may choose to limit the types of drinks served. It is acceptable to limit pre-dinner cocktails to wine, champagne, punch or a special signature drink chosen by the bride and groom. While this may not change the amount of alcohol you must buy, it is crucial in determining how much of each type of beverage you must purchase. It is very common to serve only wine and champagne during the meal, with a full bar open for the post-dinner festivities.
Determine specific beverage needs
Estimate roughly one drink per person for each hour that you plan on serving drinks at the reception. If you expect your wedding reception to last for four hours and you have invited 100 guests, estimate a total of 400 drinks.
Use the ratio of beer, wine and spirits that you determined while reviewing the guest list to calculate the amount of each type of beverage. If you expect your guests to consume 400 drinks at the wedding reception in total, that translates to 200 beers, 120 glasses of wine and 80 cocktails using the standard 50/30/20 ratio.
Calculate necessary champagne for toasting separately, using one 118 ml (4 fl oz) glass per person. Many of the guests who are otherwise beer, wine or cocktail drinkers will sip the champagne during the toast to be polite, but will probably not consume the entire glass.
Calculate total alcohol needed
Use standard per-drink consumption measures to determine the amount of alcohol you will need for your reception: 30 to 60 ml (1 to 2 fl oz) of alcohol for each cocktail, 120 ml (4 fl oz) for each glass of wine and 240 to 360 ml (8 to 12 fl oz) for each beer, depending on the size of the glass, bottle or can.
Calculate beer needs based on whether you want to serve beer on tap or in bottles or cans. For a total of 200 servings of beer, purchase a half keg for beer on tap or 33 cases of 12-pack bottles or cans.
Calculate wine based on one 750 ml (2/3 quart) bottle providing roughly five glasses of wine. For 120 glasses of wine, purchase 24 bottles, which is the equivalent of two cases.
Calculate spirits based on 44 ml (1.5 fl oz) per drink to ensure a sufficient supply. Although a standard cocktail contains 30 ml (1 oz) of alcohol, spillage and incorrect measurements may happen unless you have professionals tending bar. Since a standard 750 ml (2/3 quart) bottle will make 18 cocktails, you will need the equivalent of 4.5 bottles of alcohol.
Calculate champagne based on six glasses per bottle. For 100 flutes of champagne, purchase 17 750 ml (2/3 quart) bottles.
Use wine merchants that have a buy-back policy. As long as you ensure a minimum purchase, they will take back and refund you for any cases of alcohol that your guests do not consume. This ensures that you have a sufficient supply, but you do not have to pay for more than you need. Make sure that your venue allows you to bring your own alcohol onto the premises, and ask if they charge a per-bottle corkage fee. Knowing all of your costs upfront will save you from any nasty surprises when you get back from your honeymoon.
Monitor your guests' alcohol consumption to ensure responsible drinking. If any guests have over-imbibed, do not allow them to get behind the wheel of a car. If possible, have food and coffee available for guests during periods where you are serving alcohol.