24/7 Wall St.

Television is about to rake in millions of dollars on the royal wedding of Britain’s Prince Harry and American Meghan Markle, which will take place on Saturday, May 19. If past ratings of royal weddings are any indication, the U.S. audience could be 20 million viewers, which is higher than the viewership for a World Series game.

The price of a 30-second spot on the World Series is nearly $1 million. As many as 10 U.S. networks will cover the royal event live. Based on conservative estimates, if the wedding is televised for three hours, ad units per hour likely will be as high as 10. Some may be 30-second spots; others could run a minute. Total ad revenue across all U.S. broadcasts should be in the $50 million to $100 million range.

According to Nielsen, the viewership across all U.S. TV outlets that covered the wedding of Prince William and Kate Middleton was 23 million.

The other large source of ad revenue for TV networks are the “pre-wedding” programs that many are airing. These cover everything from the exact details of how the wedding will be staged to what traditions will be honored. Other shows will suggest what people should wear when they watch the wedding. Still others have covered the scandals surrounding Markle’s family. The royal wedding is not just a wedding but a series of events.

The PBS website for wedding coverage has a countdown for the event by day, hour, minute and second. It is an absurd example of how wild the networks have become for an opportunity that comes so rarely.