Movie previews, also known as trailers, typically last between 10 to 20 minutes before the main feature film starts. This duration can include trailers for upcoming movies, advertisements for local businesses, and promotional content for the theater itself

. For blockbuster films or special events, the preview time can be longer, sometimes extending up to 25 minutes or more

. The number of trailers shown usually ranges from 5 to 8, with each trailer lasting about 1.5 to 3 minutes

. Several factors influence the length of previews, including:

• The type of movie being shown (blockbusters tend to have longer previews).
• The theater chain and its policies.
• The format of the screening (IMAX and 3D may have additional trailers).
• Special events or promotions that might extend preview time

In summary, movie previews generally last about 15 to 20 minutes, but this can vary from around 10 minutes up to 25 minutes or more depending on the circumstances