Radio Advertisements Are Typically Sold in 30 Second Spots
Traditionally, radio spots are sold and priced based on 60 second commercial spots. However, you can buy 30 second or even 10 second spots (called billboards). Unlike television, a 30 second commercial doesn’t necessarily cost half as much as a 60 second commercial. For example, a 30 second commercial might be priced at 80% of the rate of a 60 second spot. This is because radio listeners tend to get less annoyed by the amount of time which commercial messages take than the number of different commercials that are aired. (Here is good video explanation by Dan O’Day)
There is a study that indicates that 60 second commercials are more effective than 30 second commercials. The longer commercial gives the advertiser an opportunity to tell a story and repeat their brand name and call to action more often.
Our suggestion: Go with the 30 second commercial.