Baby Sleep Calculator: Wake Windows, Total Sleep and Naps by Age

Find the wake window

Enter your baby's age in months. Add the time your baby last woke, in HH:MM, to also get the window for the next sleep. The result is the typical wake window, total daily sleep, and number of naps for that age.

What a wake window is, and why it helps

A wake window is simply how long a baby of a given age can comfortably stay awake between sleeps before becoming overtired. It is the single most useful number in baby sleep, and it is the one most parents are never told. A newborn manages only about 45 to 60 minutes awake; by six months it is two to two and a half hours; by a year, three to four.

The reason it matters is counter-intuitive: an overtired baby sleeps worse, not better. Push past the window and the body releases stress hormones that make it harder to settle and more likely to wake early. Catching the baby while still calmly tired, before the eye-rubbing turns into crying, is what makes a nap happen at all.

So the calculator gives you a window, not a clock time, because a baby's day shifts. If you tell it when your baby last woke, it adds the rough time the next sleep is due, which is far more useful than a fixed nap schedule that ignores how the morning really went.

Wake windows, sleep and naps by age

Newborn (0 to 6 weeks): about 45 to 60 minutes awake, 14 to 17 hours of sleep across the day, in four to six or more naps with no real day-night pattern yet. From 7 weeks to 3 months, 60 to 90 minutes awake and four to five naps.

Three to six months: the window opens to about two to two and a half hours, total sleep 12 to 15 hours, settling from four naps down to three. Six to nine months: two and a half to three hours awake, two to three naps. Nine to twelve months: three to four hours, usually two naps.

Twelve to eighteen months: three and a half to four and a half hours awake, dropping from two naps to one, often around 15 months. Eighteen months to three years: five to six hours awake and a single midday nap, with total sleep of 11 to 14 hours including the night.

How to use the next-nap time

Give the calculator the time your baby last woke and it returns a window, say 11:00 to 11:30, rather than a single minute. Start winding down toward the earlier end: a calm, dim, quiet few minutes before the nap does more than any exact time.

Watch the baby as well as the clock. Early tired signs, staring off, slowing down, rubbing eyes or ears, a first yawn, mean the window is closing and it is time to settle. Crying and arching are late signs, the point at which a baby has tipped into overtired and the nap gets harder.

The first wake window of the morning is usually the shortest, and the last one before bed a little longer. If naps have been short, the next window shrinks; if a nap ran long, it stretches. Use the tool as a starting point and let your baby fine-tune it.

Safe sleep comes first

Whatever the schedule, safe sleep is the part that is not negotiable. Always put your baby down on the back, never the front or side, for every sleep, day and night, until the first birthday. Back sleeping is the single biggest protection against sudden infant death (SIDS).

Use a firm, flat surface with a fitted sheet and nothing else in it: no pillow, no quilt or thick blanket, no bumpers, no soft toys. A baby is safest sleeping in the same room as you, in their own cot or bassinet, for the first six months. Keep the room comfortably cool rather than warm, and do not overdress or cover the head.

Never sleep with your baby on a sofa or armchair, and not in an adult bed if you or your partner smoke, have drunk alcohol, taken anything sedating, or the baby was premature or small. If you feed at night, put the baby back on the firm flat surface to sleep afterwards.

When to talk to your doctor

These ranges are typical, not targets, and a baby who sleeps a little more or less while feeding well, growing along the chart and content when awake is doing fine. Sleep is also not linear: regressions around 4 months, and again later, are normal and pass.

It is worth a word with your doctor if your baby is very hard to wake, unusually floppy or sleepy and feeding poorly, snores loudly or seems to stop breathing in sleep, or if sleep suddenly changes along with other signs of being unwell. Those are about health, not schedule.

For everyday sleep struggles, small and steady beats dramatic: a consistent wind-down, a dark room, and working with the wake windows rather than against them. If it is wearing you down, your doctor or child-health nurse can help rather than leaving you to tough it out.

Common questions