We all know the feeling of rushing to the cinema for our ticket time to find only ourselves sweating through 20 minutes of adverts and trailers.

Many of us enjoy the build-up - it's a chance to see the other upcoming films and get comfy with our popcorn and snacks.

But some of us don't.

And then there are some occasions when you're a bit late to your screening time but you're not sure if you'll still make the movie.

Have you heard of the 24 minute rule? (Getty Images)Have you heard of the 24 minute rule? (Getty Images) (Image: Getty Images)

The sweet spot - to avoid a lengthy wait but not miss the opening credits - is a tricky calculation.

Speaking to Sky News, the chief executive of Digital Cinema Media, which supplies advertisements for Odeon, Vue and Cineworld, Karen Spacey has explained the 24-minute rule.

The DCM chief executive noted that "in general, it's 24 minutes" in order to make room for 12 minutes each for adverts and trailers.

This rule is consistent regardless of the film or time of day since about 95% of DCM's schedules "exactly the same".

However, timings will vary between different cinema chains since there aren't any set rules or procedures.

For instance, the Cineworld website says that ads and trailers "normally last between 30-45 minutes before the actual film begins".

Customers are also asked to collect tickets at least 20 minutes before the listed time "to make the most of their visit".

Advert and trailer length at Odeon is "typically 15 to 25 minutes" in comparison but can vary with each performance and can be "considerably less".

"We always recommend to avoid disappointment you arrive with enough time to enter the screen at the scheduled performance start time," Odeon's website continues.

Everyman isn't too dissimilar with roughly 25 minutes of adverts and trailers for each film screening.

Recommended reading

Special events can also see changes to the advert time and can range from 15 to 40 minutes depending on the type of event.

Sky News reports that Vue's trailer and advert time is between 20 to 25 minutes before the film begins.

It does recommend being in your seat at the time stated so that "don't take any chances in missing the start of your film".