Are you planning to serve liquor at your wedding' Then you would not want your guests to sit with empty glasses. You need to have a proper number of bartender who would attend the needs of the guests. Ideally in a wedding for every 100 guest there are 4 bartenders that means 2 bartenders for every 50 guests.If your expecting more footfall of guest at the bar then you need additional staff and caterers charge extra for extra staff. You in a full service package which is inclusive of liquor there are 4 bartenders. If you want helping hands then you better be prepared to spend extra money.