The Nightstand · runs in your browser

Wake Window Calculator

Set the slider to your baby's age and this shows the stretch of awake time most babies that age manage before the next sleep — as a band, because that is the only shape this answer honestly has. Your baby is the authority; this is a starting point.

No account, no email, and nothing you type is sent anywhere.

Which window is this?
A rule of thumb, not a finding: the first stretch after morning wake-up tends to sit near the short end of the band, and the last one before bed near the long end. None of the sources below measures this — it moves the pale marker inside the band and nothing else.

Add a wake-up time and this will show the earliest and the latest the next sleep is likely to be wanted. It will never show one time, because it does not know one.

Awake time to expect
1h 30m – 2h 15m
Wake windows vary. This is a starting point for a baby this age, not a target and not a rule — your baby is the authority, and the band is wide because the honest answer is wide.
Drawn against a whole day, nought to eight hours
The band for this age Rule of thumb for this window
Naps at this age
Three to four
Usually, and it moves for weeks either side of a transition.
Sleep in 24 hours
12 to 16 hours per 24 hours, naps included
The published figure the band above is compiled from.
Every age, not just yours

Wake windows by age

Age Awake between sleeps Naps Sleep per 24 hours
Newborn, under 1 month 45m – 1h Four to six, often more Around 18 hours in total, in stretches of one to two hours
1 month 1h – 1h 15m Four to six No consensus figure is published under 4 months
2 months 1h – 1h 30m Four to five No consensus figure is published under 4 months
3 months 1h 15m – 1h 45m Three to five No consensus figure is published under 4 months
4 to 5 months 1h 30m – 2h 15m Three to four 12 to 16 hours per 24 hours, naps included
6 to 7 months 2h – 3h Two to three 12 to 16 hours per 24 hours, naps included
8 to 10 months 2h 30m – 3h 30m Two to three 12 to 16 hours per 24 hours, naps included
11 to 12 months 3h – 4h Two 12 to 16 hours per 24 hours, naps included
13 to 17 months 3h 30m – 4h 30m One or two 11 to 14 hours per 24 hours, naps included
18 to 23 months 4h – 5h 30m One 11 to 14 hours per 24 hours, naps included
2 to 3 years 5h – 7h One, or none at all 10 to 13 hours per 24 hours, naps included

Every row is a range and every range is wide, because that is what the underlying figures are. A page that prints one exact number of minutes for a whole age band has invented it. Where a source publishes no figure at all — and under four months none does — this table says so rather than filling the gap.

What this is. An estimate, worked out from published total-sleep figures and the number of naps babies usually take at a given age. It is arithmetic on an average, and it cannot see your baby. Wake windows vary — treat any band here as a starting point and let three or four evenings of your own notes overrule it, because they are about her and this page is not.

What it refuses to do. It will not print one number of minutes, because nothing this site may cite publishes one. It will not tell you what your baby should be doing by a given month, and it does not attach a month to sleeping through the night: waking at night is ordinary well past the first birthday. It has no opinion on any sleep-training method, and there is no AI in it — it is a slider and some arithmetic that runs in this browser.

Safe sleep first, whatever the timing says. Every sleep happens the same way: on their back, on a firm flat surface, in a cot clear of blankets, pillows, bumpers and soft toys, in your room for at least the first six months. Nothing weighted goes on or over a sleeping baby. If your baby is very hard to settle, unusually sleepy, feeding poorly, or something simply feels wrong to you, that is a call to your pediatrician or health visitor rather than a timing problem — and none of this is medical advice.

How this is worked out

  1. You give it one thing: your baby's age in whole months. Everything on the page is read off that, and nothing you type leaves your browser.
  2. The bands are compiled from total-sleep guidance rather than copied from a wake-window table, because no publisher this site is allowed to cite publishes one. The American Academy of Sleep Medicine's consensus — which the American Academy of Pediatrics endorses — gives 12 to 16 hours per 24 hours including naps at 4 to 12 months, 11 to 14 hours at 1 to 2 years and 10 to 13 hours at 3 to 5 years. Take that total, take the number of naps babies that age usually still have, and the awake stretches between them fall out as a range.
  3. For babies under 4 months there is deliberately no consensus figure at all: the sleep panel declined to publish one because the normal variation is too wide. The NHS puts a newborn's total at around 18 hours and says babies may only manage 1 or 2 hours of sleep at a time. Those bands are therefore the widest and the softest on the page, and they are labelled as such.
  4. Where you are inside the band is a rule of thumb rather than a finding: the first window after morning wake-up tends to sit near the short end and the last stretch before bed near the long end. The page marks that on the band and says plainly that no source below supports it — it is a pattern parents and this app both see, not a measurement.
  5. If you enter the time your baby last woke, the page adds the band to it and shows two clock times: the earliest and the latest the next sleep is likely to be wanted. It never prints one time, because it does not know one.
Questions

The short answers

A wake window is the stretch of time a baby is awake between one sleep and the next — from the moment she opens her eyes to the moment she goes down again. It is a description, not a rule. Newborns manage under an hour of it and a two-year-old can manage most of an afternoon, and the whole reason the phrase is useful is that awake time grows in a fairly predictable order even though the exact minutes are different for every baby.
Start with the band for her age above, then watch what actually happens for three or four days. Note the time she wakes and the time she settles, and look at the gaps. If she goes down easily and sleeps a decent stretch, that gap was about right; if she fights the cot or wakes after twenty minutes, try a shorter one and then a longer one before deciding. Four days of your own notes beats any table on the internet, this one included — which is the whole argument for writing them down.
Use the by-age table on this page as the outer edges rather than the target. The bands are wide on purpose: at four months the difference between the short end and the long end is the better part of an hour, and babies sit at both ends of it perfectly happily. Ages here are in whole months from birth, and if your baby was born early, most guidance is followed from the due date rather than the birth date for the first year.
It is arithmetic on an average, and it says so. No calculator can see your baby: the bands here are compiled from published total-sleep guidance, and the sources they are built from give ranges rather than figures. Treat any window as the middle of a wide estimate and let the evening tell you the rest. A page that prints one exact number of minutes has made that number up.
Usually nothing dramatic, and it is worth saying that plainly, because most of what is written about this is written to worry you. Too short and a baby often will not settle, or takes a short nap and wakes cross. Too long and settling can get harder rather than easier. Neither is damage; both are information for the next attempt. What matters far more than the minutes is that every sleep happens the same safe way: on their back, on a firm flat surface, in a cot clear of blankets, pillows and toys.
Only in this browser, and only so the page remembers your baby's age next time you open it. It is saved in your own browser's local storage under one key, nothing is sent to a server, there is no account and no request carries anything anywhere. The Clear button underneath the calculator deletes it, and closing a private window does the same.

Where this comes from

  1. Journal of Clinical Sleep Medicine (PubMed Central) (2016). Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC4877308/
  2. American Academy of Pediatrics (HealthyChildren.org) (2024). Healthy Sleep Habits: How Many Hours Does Your Child Need?. https://www.healthychildren.org/English/healthy-living/sleep/Pages/healthy-sleep-habits-how-many-hours-does-your-child-need.aspx
  3. NHS (2025). Helping your baby to sleep. https://www.nhs.uk/baby/caring-for-a-newborn/helping-your-baby-to-sleep/
  4. American Academy of Pediatrics (HealthyChildren.org) (2024). Getting Your Baby to Sleep. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/getting-your-baby-to-sleep.aspx
  5. American Academy of Pediatrics (HealthyChildren.org) (2022). How to Keep Your Sleeping Baby Safe: AAP Policy Explained. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/A-Parents-Guide-to-Safe-Sleep.aspx
  6. NHS (2025). Reduce the risk of sudden infant death syndrome (SIDS). https://www.nhs.uk/baby/caring-for-a-newborn/reduce-the-risk-of-sudden-infant-death-syndrome/

Every link above was opened and read when this page was last updated. Snuggle is not affiliated with any of these organisations and none of them has reviewed this page. Nothing here is medical advice.

Go deeper

The reading behind this page

Sleep, by age · 8 min read

Wake Windows by Age

How long babies stay awake between sleeps at every age, drawn as bands — plus the part nobody else prints: where the numbers come from, and what they are not.

Read it Sleep, by age · 9 min read

How Much Sleep Does a Baby Need by Age

The one place in this subject where real numbers exist — printed at their published width, with the ages the sleep panel refused to cover left honestly blank.

Read it Sleep, by age · 10 min read

Newborn Wake Windows

Under an hour awake between sleeps, most of it spent feeding and changing — what the first weeks are really made of, and why nobody can hand you a timetable for them.

Read it Sleep, by age · 9 min read

Wake Windows for a 4 Month Old

An hour and a half to two and a quarter hours awake, three or four naps — and the month a baby's sleep grows cycles, which is why everything got harder at once.

Read it Sleep, by age · 8 min read

Wake Windows for a 6 Month Old

Two to three hours awake, two or three naps, and the month the day changes size — with the published numbers on night waking, which is more ordinary than anybody tells you.

Read it Sleep, by age · 8 min read

Toddler Wake Windows

Three and a half to seven hours awake, depending on the age — one nap, two very long stretches either side of it, and a bedtime that has learned to argue.

Read it
Next door

Baby Sleep Schedule Generator

Your baby's age and this morning's wake-up, drawn as a day: naps and bedtime as windows, widening through the afternoon the way real days do.

Open it

Nap Transition Checker

Age plus the signs you are actually seeing, and an honest read on which nap transition is near — including the answer that it is not one yet.

Open it

Sleep Regression Timeline

The famous ages, one at a time: what is genuinely developing then, what tends to happen to the nights, and what nobody can actually tell you.

Open it
The app this site is for

Snuggle does this with your baby’s own pattern.

This page works from an age band, because an age band is all a web page knows about you. Snuggle starts from the same bands and then blends them with what your baby actually did today — how long she lasted, when she went down, how the last nap ran — and shows on the face of the ring how sure it is. Early estimates say they are early.

It logs sleep, feeds, nappies and growth in one tap on a dim red screen, and every caregiver in the household is on the same timeline in their own account. The arithmetic runs on the phone, on your baby’s own history. There are no AI features in it.

In development for iPhone and Android. Not released yet — when it is, it will be on this site.

What Snuggle is