Short answer: about five minutes, read slowly. Long enough for a beginning, a middle and an end; short enough to finish before the yawns turn into tears. The longer answer depends on your child's age, on the time of night, and on what the story is for.

Why five minutes

A bedtime story has to do two things that pull in opposite directions. It has to be absorbing enough to hold a child's attention away from the day, and it has to be over before that attention runs out. For most children between about three and eight, that window is somewhere around five minutes of calm reading. Less, and there is no time to settle; more, and the story is competing with sleep instead of leading to it.

That is the length every story here is written to. It is not a limit on the stories so much as a promise about the evening: you know, before you start, when it will end.

What changes with age

Toddlers and two-year-olds want less: a few minutes, familiar things, and the same story again. Repetition is not a failure of imagination on their part; it is how they learn the words. Three- and four-year-olds can follow a short adventure and start to want the ending to mean something. By six or seven, a child can enjoy a longer story — but bedtime is still not the place for it. Save the chapter book for the sofa on Sunday; at bedtime, five minutes of something complete works better than twenty minutes of something that stops in the middle.

Older children who still like being read to — most do, whatever they say — often prefer true stories at bedtime: something about the world, told calmly, that gives the mind a fact to hold rather than a plot to worry about.

"Just one more"

Every parent hears it, and it is a compliment. It is also the moment the routine either holds or does not. The trick is to answer it before it is asked: say at the start how many stories there will be, and make the last one the one your child chose. A child who picked the story is far more willing to let it be the last.

If you do say yes to one more, make it shorter than the first. The evening should get quieter as it goes, and the stories should too.

Reading slowly

Whatever the length, read slower than feels natural. Pauses at the end of sentences. A beat at each page turn. A five-minute story read at a walking pace is worth more than a ten-minute story read at a run, and it ends with a calmer child. The narrated stories here are recorded at that pace on purpose, and you can slow them further in the reader.