While many of cable’s dramatic series are often described as weekly mini-movies, FX has taken that notion a step further.

In the fifth season of “Sons of Anarchy,” ending next Tuesday, five of the 13 episodes have run 90 minutes. Normal running time for an episode is 60 minutes, but the cabler has clearly changed the rules for the current season of “Sons.”

While “Sons” has gone long for an episode or two in past seasons, it’s highly unusual for nearly half a dozen episodes in one season.

Other nets, specifically HBO and Showtime, often go long with a series finale or premiere, but usually for only 10-15 minutes. A full extra half-hour is rare.

FX president John Landgraf said that while that practice began many years ago on “Nip/Tuck” and “The Shield,” it has become more commonplace because it gives the cabler a chance to keep up with the creative scope of HBO and Showtime, which aren’t forced to cut into their series with commercial breaks.

An hourlong FX episode consists of about 42 minutes of content, while a 90-minute episode equals about an hour of storytelling — similar in length a typical episode of such highly praised series as “Boardwalk Empire” and “Homeland.”

“If an episode of ‘Sons’ comes in at 55 minutes, you would have to cut 13 minutes,” Landgraf explained. “I’d rather turn that into an hour and a half.”

Creator and exec producer Kurt Sutter said as the story has ramped up this season — with Jax (Charlie Hunnam) trying to navigate his club out of troubled situations with cartels and gun-running — it has been difficult to keep each episode at an hour.

“The truth is that it’s hard whittling them down to 90 minutes,” Sutter said of the final episodes of the season. “We’re certainly not padding them or wanting to put scenes back in.”

Sutter believes it would hurt the integrity of the show to chop a scene in order to make the 60-minute mark. “The worst thing to do is cut the scene and bring the life out of it,” he explained. “We’re like a Western. What I try to do is let these scenes breathe and give them the spaces to be potent and real.”

Landgraf said there are no substantial additional costs in adding the extra 30 minutes aside from some post-production expenses. There would be substantial additional costs if an episode stretches to two hours, when it becomes classified as a movie, but that has never been the case.

The only downside to the 90-minute episodes, Landgraf explains, comes on the international side. “Sons” is sold by 20th Century Fox to global buyers, who expect each episode to be an hour.

And as long as the listings are sent to DVRs in time, the 90-minute episodes shouldn’t be cut off in mid-episode. The episodes that run only two or three minutes past the hour can often be more irritating for those who watch on DVR, since that will cut into another show at the top of the hour and create a programming logjam.

If watching live, the 10 p.m. start makes for a latenight 11:30 p.m. finish, but fans are both staying up and watching later on this season in record numbers. “Sons” is averaging 6.4 million total viewers and 4.4 million in adults 18-49 in live-plus-7. That’s up 15% and 16%, respectively, vs. season four.