Movie previews at theaters typically last between 10 to 20 minutes before the main feature begins. For blockbuster films or special events, this preview time can extend up to 25 minutes or even longer in some cases

. The length of previews varies depending on factors such as the theater chain, the type of movie being shown, and the format of the screening (e.g., IMAX or 3D may have longer previews)

. Most theaters show around 5 to 8 trailers, each lasting about 1.5 to 3 minutes, plus some ads or promotional content

. In summary:

• Average preview length: 10 to 20 minutes
• Blockbusters or special events: up to 25 minutes or more
• Number of trailers: typically 5 to 8
• Trailer length: about 1.5 to 3 minutes each

This preview time is additional to the movie's official runtime, which usually does not include the previews