There are many factors that affect non-profit ticket sales. You will never be able to estimate the exact number of tickets until the day when you actually stop selling them, but there are a couple of ways to get an idea of how many tickets you might sell:
Check ticket sales for similar events. You might find that someone else has held a similar event to yours in the area and ask them how many tickets they sold. The numbers might not be accurate, but it should give you a number to start with.
You can also put flyers or programs in public places like shops in the area. If you count how many you put out and then go back and collect them and find out how many were actually picked up, you might get an idea of how many people were interested. Of course, the actual attendees could range from 2 or 3 percent to as high as fifteen, but it is a good starting ticket system for non-profits to estimate with.
Finally, you could set up a website and keep track of how many hits you get as you tell people about the event. You might be able to get a quarter or half of the visitors that came to your website to buy a ticket. The best way to do this is by putting a contact form on the site where you can have an email or mailing address and allow them to purchase tickets or reserve tickets online.
Keep track of your sales curve and use it to predict total sales once sales start. For example, some community theatres tend to sell half the total in the first two weeks of sales. Once those two weeks are up, you have a pretty good idea what your total sales are going to be.
And check popular weekly ads:
Kroger Weekly Ad, Target Ad, Walgreens weekly Ad, Meijer weekly Ad
Aldi Catalogue, Aldi Catalogue, Big w Catalogue, Bunnings Catalogue