The wedding cake is a centerpiece of the reception, and determining the right size can feel stressful. You want enough slices for your guests without having excessive waste. Fortunately, there's an expert-backed way to estimate your needs. Calculating the Servings Start with your guest count, but don't feel obligated to cater to 100% of your attendees. Estimate Guest Consumption: Experts suggest planning for 75% to 85% of your guests to enjoy a slice of cake. Some guests ma