How long is an hour TV show? It sounds like a corny joke, like, Who’s buried in Grant’s tomb? or How many gallons does a 10-gallon hat hold? or How many years did the Hundred Years’ War last? (It actually lasted 116 years.)

So how long is an hour TV show? One hour, right? Not so fast. According to a 2014 study from the ratings measurement firm Nielsen[1], the average 1-hour TV show has only 45 minutes and 45 seconds of content, plus 14 minutes and 15 seconds of commercials. Commercial time increased by 6% in the five years covered by the Nielsen study, so the amount of watchable content is actually shrinking. That’s broadcast TV.  For cable networks, the average commercial time was almost 10% higher, clocking in at a greedy 15 minutes and 38 seconds. Some cable companies are even speeding up their shows by using compression technology so they can cram even more commercials into an hour[2].

Even with all of the commercials, it still takes an hour to watch the show, right? Not if you watch the show on Netflix or Amazon, where there are no commercials. If they skip the intro and closing credits, your kids should be able to get through an average episode of whatever mind-numbing, brain-melting show they’re watching in about 40 minutes with one of these online services.

Now picture this familiar scene: Your kid (usually 10 and under) is watching a show or video.

You: “It’s time for (fill in the blank – bed/bath/beyond)”

Kid: “Can I just watch the end of this show/video?”

You: “How much time is left?”

Kid: “It’s almost over.”

“Almost” is a relative word. The recession is “almost over” too, except for all those people who are unemployed or underemployed.  The wait for Mad Men to resume its final season was “almost over,” but no one knew for sure.  That Grateful Dead guitar solo is “almost over” too.  The war in (insert middle-eastern country) is almost over as well, except it’s not and will most likely never be. You get the picture.

You’re ready for this one, though. Knowing that the typical one-hour Netflix show is no more than 40 minutes long, and that the law of averages would indicate that on any given day you’re going to walk in when the show is half over, almost over probably means 5-10 minutes to you, right? Maybe 15 minutes at the most. Because you’re good at math. You took calculus and statistics…multiple times.

But by the time you realize that the show/video just started and is not even close to being over, you’ve already agreed to let your kid watch until it’s over, at which point you’ve given up and gone to sleep, because your day is actually over.

[1] TV networks load up on commercials, http://www.latimes.com/entertainment/envelope/cotown/la-et-ct-nielsen-advertising-study-20140510-story.html

[2] Cable networks are speeding up TV shows to cram in ads, http://www.cbsnews.com/news/cable-networks-are-speeding-up-tv-shows-to-cram-in-ads/