Having a wedding, festival or any other outdoor event and not sure how many portable toilets you will require? There are many different factors to consider. The most important factor is how many people will attend the event. Then consider if you will be serving food or especially alcohol. When you serve drinks and food you might have to factor guests using the bathroom more often. However, I have posted a table at the bottom that figures the basic needs per a certain number of people. When in doubt get more then less. One less toilet might save money, but when the lines are long or even worse the toilets are full you will wish you had an extra portable toilet.