Baby sleep schedule and wake window calculator
Enter your baby's age and the time they woke, and this tool works forward through age-appropriate wake windows to suggest nap times and a bedtime. It shows the full published range beside every suggested time, because wake windows are a parenting framework rather than clinical guidance. Safe sleep guidance is shown above the answer, not below it. It runs entirely in your browser.
Baby sleep schedule and wake window calculator
No sign-up · PrivateUnder 4 months this tool will not produce a schedule, because the AASM consensus the AAP endorses publishes no sleep recommendation below that age.
The morning wake-up is the only anchor the whole day hangs off. Everything below is measured forward from it.
Your own observation, not guidance — no official body publishes a nap length at any age, so the tool is not going to pretend one exists. It changes where bedtime lands, not the total sleep.
Suggested bedtime, working forward from a 7:00 am wake-up
Naps: 2 naps of 1 hour — the length you entered, not a recommendation
Awake between sleeps: 3h 45m (the middle of the published 1h 30m to 6 hours range)
Total sleep in this plan: 12h 45m in 24 hours, against the 12 to 16 hours the AASM consensus recommends for 4 to 12 months
Night stretch: 10h 45m
First nap could reasonably start: anywhere from 8:30 am to 1:00 pm
Nothing you type leaves your device. The whole calculation runs in your browser.
How this is calculated
FormulaHow this schedule is calculated
The arithmetic, in one line
Between waking and bedtime, a day is n wake windows with n−1 naps in between, and then the night. All the awake time in twenty-four hours is therefore the wake windows, which means:
total sleep in 24 hours = 24 − n × W
That expression does not contain the nap length at all. Nap length moves where bedtime lands and nothing else. The tool chooses n so that the total lands closest to the middle of the evidence-based total-sleep band for the age, then:
- bedtime = wake time + n × W + (n−1) × nap length
- night stretch = 24 hours − (bedtime − wake time)
Worked example. A 9-month-old who woke at 7:00 am, with naps that usually run an hour: the wake window used is 3 hours 45 minutes, the tool picks 3 wake windows and therefore 2 naps, total sleep comes out at 12 hours 45 minutes (inside the recommended 12 to 16 hours), naps fall at 10:45 am and 3:30 pm, bedtime lands at 8:15 pm and the night stretch is 10 hours 45 minutes. Change the nap length to 90 minutes and bedtime moves to 9:15 pm — but the total is still 12 hours 45 minutes.
Wake windows: what they are, and what they are not
“Wake window” is a popular parenting and sleep-consultant framework. It is not a clinical concept and no official body publishes wake-window numbers. The term does not appear on the NHS baby-sleep pages. It does not appear on the American Academy of Pediatrics’ baby-sleep pages. It does not appear anywhere in the American Academy of Sleep Medicine consensus statement on paediatric sleep duration — that statement legislates total hours per 24 hours and never the length of an awake interval.
Dr Craig Canapari, director of the Yale Pediatric Sleep Center, put it plainly: “This is not a concept that is taught, discussed, or researched in medical school or in the world of pediatric sleep medicine. A Pubmed search pulled up zero references on the term.” He adds that “the numbers describing how long wake windows should be at various ages do not seem to be based on any scientific evidence.” The underlying physiology is real — sleep pressure builds while a baby is awake, faster in younger children — but the hour-by-age charts are not derived from it.
So this tool names its source for the numbers rather than implying they are guidance. They come from the Sleep Foundation’s published chart, medically reviewed by Nilong Vyas, MD, MPH:
- 0 to 1 month: 0.5 to 1.5 hours (midpoint used: 1 hour)
- 1 to 4 months: 1 to 3 hours (midpoint used: 2 hours)
- 5 to 7 months: 1.5 to 4.5 hours (midpoint used: 3 hours)
- 7 to 10 months: 1.5 to 6 hours (midpoint used: 3 hours 45 minutes)
- 10 to 12 months: 3 to 7.5 hours (midpoint used: 5 hours 15 minutes)
The chart’s own caveat: “Every infant is different and operates on their own schedule, so your baby’s wake windows may look different than another’s and can actually change from one day to the next.”
Two honest notes about that table. It leaves a gap between 4 and 5 months, and this tool carries the 1-to-4-month band across it rather than inventing a band. It also stops at 12 months, and past a year the 10-to-12-month figures are carried forward, which is an assumption of this tool and not something the source publishes.
Why the tool shows you the whole range
Look at the 7-to-10-month band: anywhere from an hour and a half to six hours. Chain three of those across a day and the resulting bedtime for a 9-month-old who woke at 7:00 am lands anywhere between 1:30 pm and 3:00 am. That twelve-and-a-half-hour spread is not a defect in this tool. It is the honest width of the framework, and it is why every row of the schedule shows the full range next to the suggested time. Treat the suggested column as a place to start on an ordinary day, not a timetable to hit.
Total sleep: the figure that does have evidence behind it
The AASM consensus recommendations, endorsed by the American Academy of Pediatrics (Paruthi et al., J Clin Sleep Med 2016;12(6):785–786), are what the plan is anchored to:
- 4 to 12 months: 12 to 16 hours per 24 hours, including naps
- 1 to 2 years: 11 to 14 hours per 24 hours, including naps
- 3 to 5 years: 10 to 13 hours per 24 hours, including naps
And the footnote that governs this entire tool, verbatim: “Recommendations for infants younger than 4 months are not included due to the wide range of normal variation in duration and patterns of sleep, and insufficient evidence for associations with health outcomes.”
So under four months this calculator will not produce a schedule. It shows a rolling rhythm instead — the times a baby may be ready to sleep again — with no bedtime and no night, because the NHS is clear that newborn babies do not know the difference between day and night. The NHS puts newborn total sleep at “around 18 hours”, and says that “some newborns may sleep for a total of around 8 hours a day, while others may sleep up to around 18 hours a day – either is perfectly normal.” For older babies the NHS adds that “By the time your baby is around 6 months old, they may sleep for up to 12 hours at night” and that “Most babies will sleep around 12 to 15 hours in total after their first birthday.”
No official body publishes a nap length at any age, which is why this tool asks you for one instead of inventing it. Your answer is your observation of your own baby.
Safe sleep, which comes before any schedule
These are shown above the result on every state of the tool, including errors and the blank form, and they do not depend on anything you type. Sources: The Lullaby Trust, the NHS, and the AAP’s 2022 policy statement.
- Back to sleep, every sleep. The Lullaby Trust puts it as ABC: “Always sleep your baby on their back in a clear cot or sleeping space.”
- A clear cot. The Lullaby Trust: babies need just two things in the cot — “A firm, flat, waterproof mattress” and “Lightweight bedding”. No pillows or duvets, no cot bumpers, no soft toys or comforters, no weighted or bulky bedding, and no pods, nests, rolled-up towels or anything soft placed on top of the mattress.
- Room sharing. A separate cot or Moses basket in the same room as you, for every sleep, for at least the first 6 months. The Lullaby Trust, the NHS and the AAP all say the same thing here.
- A firm, flat, non-inclined surface. The AAP’s 2022 recommendations name “a firm, noninclined sleep surface”, and the AAP adds that firm “means that it shouldn’t indent when your baby is lying on it”. UK guidance uniquely also specifies waterproof.
- Never fall asleep on a sofa or in an armchair with your baby. NHS: “Do not sleep on a sofa or in an armchair with your baby.” The Lullaby Trust says this significantly increases the risk of SIDS.
- Smoke-free, and not too hot. The Lullaby Trust and the NHS both give a room temperature of 16 to 20°C. The AAP says avoid overheating but publishes no number — a real UK/US difference rather than an omission.
- Rolling. Once your baby can roll from back to front and back again on their own, they will find their own sleeping position (Lullaby Trust). Still start every sleep on the back.
The AAP 2022 statement also lists human milk feeding, offering a dummy or pacifier at sleep, routine immunisation, and avoiding nicotine, alcohol, cannabis, opioids and illicit drugs. The NHS phrases the dummy more softly — “think about using a dummy to settle your baby to sleep” — and uses the “feet-to-foot” position, with your baby’s feet at the bottom of the cot, which is UK-specific wording.
A schedule tool that tells you how much to trust it
Type “wake windows” into a search box and you will find dozens of charts, all confident, most of them disagreeing with each other by an hour or more at every age. What almost none of them tells you is where the numbers came from.
Here is the answer: not from the NHS, not from the American Academy of Pediatrics, and not from the American Academy of Sleep Medicine. None of those bodies uses the term at all. The concept is a parenting framework that grew up in sleep consulting, and it became popular because it is genuinely useful as a mental model — babies do get harder to settle the longer they have been awake, and that part is real physiology. What is not real is the idea that there is a correct number of minutes for a given age, published somewhere authoritative, that you are either hitting or missing.
So this tool does the schedule you came for, and then shows you its own margins. Every row has the suggested time and, beside it, where that row would land if you used the full published range instead of its midpoint. For a 9-month-old, that second column puts bedtime anywhere from mid-afternoon to the small hours. Once you have seen that, the suggested column stops looking like a target and starts looking like what it is: a reasonable place to begin on a day when nothing else is going on.
Under four months, there is no schedule to find
This is the part worth saying loudly, because it is where the most anxiety lives.
The AASM consensus that the AAP endorses covers 4 to 12 months, 1 to 2 years and 3 to 5 years. It stops short of four months deliberately, and it explains why: “the wide range of normal variation in duration and patterns of sleep, and insufficient evidence for associations with health outcomes.” In other words, the people best placed to publish a newborn sleep target looked at the evidence and declined.
The NHS says the same thing in plainer language: total sleep “varies, but can be around 18 hours”, and eight hours a day and eighteen hours a day are both described as perfectly normal. Newborns do not distinguish day from night, so there is no night to build a bedtime around yet.
If your baby is under four months, this tool will not give you a bedtime. It gives you a rolling rhythm and says out loud that it will not hold. That is not the tool failing to do its job. That is the answer.
The one thing that is not negotiable
Everything above is a framework, a starting point, something to adjust. The safe-sleep guidance is not, which is why it sits above the result rather than beneath it, and why it stays on the screen when you have typed nothing at all or typed something wrong.
Back to sleep. Their own clear, flat sleep space. Nothing soft in the cot. In your room for the first six months. Never asleep on a sofa or in an armchair with them. Those are not sleep-optimisation tips and they are not in competition with a nap schedule. A tool that helps you plan a day and lets those slide off the bottom of the page has got its priorities exactly backwards.
And if the day does not match the table
It will not. Teeth, illness, a growth spurt, a car journey, a bad night before, a nap that ended after twenty minutes for no reason anyone will ever know. A day that does not match the schedule is a normal day, not a failed one. If your baby is sleeping a normal amount across twenty-four hours and seems well and content, there is nothing to fix, whatever the clock says about when it happened.
Sources
- Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine (Paruthi et al., J Clin Sleep Med 2016;12(6):785-786) — endorsed by the AAP — American Academy of Sleep Medicine, accessed
- Helping your baby to sleep — NHS, accessed
- Your baby's sleep patterns — NHS (Best Start in Life), accessed
- Safer sleep advice — the six steps, the ABC, the clear cot and the 16 to 20°C room temperature — The Lullaby Trust, accessed
- Reduce the risk of sudden infant death syndrome (SIDS) — NHS, accessed
- A Parent's Guide to Safe Sleep — American Academy of Pediatrics (HealthyChildren.org), accessed
- Moon RY, Carlin RF, Hand I; Task Force on Sudden Infant Death Syndrome and Committee on Fetus and Newborn. Sleep-Related Infant Deaths: Updated 2022 Recommendations for Reducing Infant Deaths in the Sleep Environment. Pediatrics. 2022;150(1):e2022057990 — American Academy of Pediatrics, accessed
- Safe Sleep (clinician and patient resources) — American Academy of Pediatrics, accessed
- Newborn Wake Windows — the wake window chart used by this tool, medically reviewed by Nilong Vyas, MD, MPH — Sleep Foundation, accessed
- Do wake windows help kids nap better? — on the evidence status of the term, by the director of the Yale Pediatric Sleep Center — Craig Canapari, MD, accessed