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MasterMath

Baby Sleep Calculator

An eight-month-old needs between twelve and fifteen hours of sleep a day, naps included. Check the recommended range for their age and compare it with what they actually sleep.

Recommended sleep a day

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Recommended sleep a day—
At night—
Naps—
What they sleep now—
Age band—

How this was worked out

    Indicative result. These ranges are population recommendations, not targets. A baby who sleeps slightly less and is alert, feeding and gaining weight normally does not necessarily have a problem; if their sleep worries you, talk to your paediatrician.

    The formula

    total sleep = night sleep + naps

    Where it comes from

    The ranges used are the National Sleep Foundation's, published in 2015 after reviewing more than three hundred studies. They are published as wide intervals precisely because sleep needs vary a lot between children of the same age: the gap between the low and high ends is three hours, and both figures are normal.

    How to work it out by hand

    1. Find the age band they fall into
    2. Add what they sleep at night to what they sleep in naps
    3. Compare that total against the recommended interval
    4. Look at the number of naps too, which falls with age

    What is worth knowing

    What changes most with age is not the total but how it is spread: a newborn sleeps almost as much by day as by night, in two or three hour stretches, and starts consolidating night sleep around four months. Naps merge over time — from four or five to two, then to one — and each of those transitions usually comes with a few rough weeks. A baby waking at night at eight months is not a sign of anything: brief wakings are part of the normal cycle at that age.

    Frequently asked questions

    How many hours should a 6-month-old sleep?

    Between twelve and fifteen a day, naps included, with two or three naps.

    When do babies sleep through the night?

    There is no fixed age. Many manage long stretches around six months, and waking stays normal through the first year.

    Is it too little if they are at the low end?

    Not necessarily. The range is wide on purpose; what matters is how they are awake, whether they feed and whether they gain weight.

    Do naps steal night sleep?

    The opposite: an overtired baby usually sleeps worse at night. Naps drop away on their own with age.