# Wake Window Calculator & Baby Sleep Schedule _How long your baby can stay awake, how many naps to expect, and a sample day built from your baby's wake-up time._ - Source: https://proba.baby/en/tools/wake-window-calculator - Language: English - Last verified: v1.0.4 · 7 Sep 2026 - Last updated: 2026-10-11 ## How it works Enter your baby's birth date, or just an age in weeks or months. In Wake windows mode the calculator shows how long a baby of that age typically stays awake between sleeps, how many naps a day to expect, and how much sleep the whole day usually holds, split into night and day. Add the time your baby last woke up and it also shows when the next sleep is likely to be due — the moment to start watching for sleepy cues, not an alarm. Switch to Sleep schedule mode and enter the time your baby usually starts the day. The calculator lays out a sample day: a wake window before each nap, naps of equal length, and a bedtime one more wake window after the last nap. A 5-month-old who wakes at 07:00, for example, gets naps at 09:15, 12:40 and 16:05 and a bedtime of 19:30. The numbers are the nine age bands the ProbaBaby app's Sleep Schedule tool uses, from newborn to 18 months and over. For the first two bands — the first eight weeks — the page says plainly that the day is a rhythm, not a timetable: feeds come first and naps happen when your baby is ready. From two months the sample day starts to follow the clock. Every number here is a range for healthy babies, not a target. Two thriving babies of the same age can be a nap apart, and your baby's cues — a distant gaze, yawning, rubbing eyes, fussing mid-feed — are a better guide than any table. Nothing you enter is uploaded; the inputs live in the page address, so you can bookmark a result or send it to whoever does the next shift. ## The math Age. From a birth date the calculator counts whole days. From a typed age it uses weeks × 7, or months × 30.4375 rounded — WHO's average month — so “4 months” is day 122, the start of the 4–6 month band. The bands run, in days from birth: 0–27, 28–55, 56–90, 91–120, 121–181, 182–272, 273–364, 365–545 and 546 onwards, and a baby belongs to the first band whose last day has not passed. Next sleep. The time your baby woke up plus the band's wake window, at both ends. At 4–6 months the window is 2 h to 2 h 30 min, so a baby who woke at 13:20 is due to sleep between 15:20 and 15:50. Sample day. Nap length = the middle of the band's day-sleep range divided by the number of naps in the sample day, kept inside the band's nap-length range and rounded to 5 minutes. Each nap starts one wake window after the last sleep ended, and bedtime comes one wake window after the last nap. Worked example, 4–6 months: day sleep 3–4 h, middle 3.5 h = 210 min, over 3 naps = 70 min each; the window is 135 min. Woke 07:00 → nap 09:15–10:25 → nap 12:40–13:50 → nap 16:05–17:15 → bedtime 19:30. Where the ranges come from. The bands' total sleep stays within the World Health Organization's ranges: 14–17 hours from birth to 3 months, 12–16 hours from 4 to 11 months and 11–14 hours for one- and two-year-olds, naps included; the 3–4-month band, at 13.5–15.5 hours, falls at the changeover between the first two. The American Academy of Sleep Medicine gives the same 11–14 hours at one and two years and 10–13 hours from age three, while the last band here, 18 months and over, keeps 11–14. The AASM gives no figure under 4 months at all, because normal newborn sleep varies so much. Wake windows themselves are a convention. No guideline body publishes a wake-window table; the figures are arithmetic and observation laid over the sleep totals, and nap counts follow the averages of a 2012 review of 34 studies, whose normal ranges are wide. This is the same engine as the app, checked against the app's own output for both edges of all nine bands and for twelve sample days. ## FAQ **What is a wake window?** A wake window is the time a baby is awake between the end of one sleep and the start of the next. It is a parenting convention rather than a clinical measurement — WHO, the AAP and the NHS publish total sleep per day, not wake-window tables — but it is a useful way to guess how much awake time a baby of a given age can manage before settling gets hard. **How long should a newborn stay awake?** For the first four weeks this calculator uses 45 to 60 minutes, which is roughly one feed, a nappy change and a cuddle; other charts quote from about 35 minutes. Newborns sleep in short stretches around the clock, so treat the window as a ceiling to notice, not a schedule — feeding comes first in the early weeks. **How many naps does a baby need?** As a guide: 4 to 6 short naps in the first month, 3 to 5 at 2–3 months, 3 at 4–6 months, 2 to 3 at 6–9 months, 2 at 9–12 months, 1 to 2 at 12–18 months and 1 from 18 months. The averages in research are lower and the normal ranges wide, so a baby who does well on one nap fewer is not doing anything wrong. **When do babies drop to two naps, and then one?** The bands move from 3 naps to 2 to 3 between 6 and 9 months, to 2 by 9–12 months, and to 1 or 2 between 12 and 18 months. The usual sign is a nap your baby fights for a week or more while the others stay fine. Because the window and the nap count are one sum, dropping a nap lengthens every wake window that day. **Should my newborn be on a schedule?** No. In the first two months the calculator deliberately shows a rhythm rather than a timetable: feeds come first, and your midwife or paediatrician may even ask you to wake a newborn to feed. The sample-day times start to mean something from about two months, when daytime and night-time sleep begin to separate. **My baby doesn't fit the numbers. Is something wrong?** Usually not. The ranges describe healthy babies and still miss many of them. If your baby feeds well, gains weight and settles, the table is wrong about your baby, not the other way round. Talk to your paediatrician or health visitor if your baby is unusually sleepy or hard to wake, feeds poorly, snores or pauses in breathing during sleep, or if you are worried for any reason. **Why do wake windows grow so fast around 3 to 4 months?** Because sleep is reorganising. A 2012 review of infant sleep puts the emergence of the body clock at around 10 to 12 weeks, after which sleep becomes more and more nocturnal, and the AAP says babies do not have regular sleep cycles until about 4 months. Naps consolidate, nights lengthen, and in the bands here the window grows by more than an hour between 2 and 6 months — from 1 h 15 min–1 h 45 min to 2 h 30 min–3 h. **Do wake windows apply to premature babies and twins?** The bands count from birth. For a baby born early, ask your paediatrician whether to read them by corrected age — the age counted from the due date — which our corrected age calculator works out. Twins can share one sample day if that makes life easier, but each baby's cues still decide when that baby sleeps. ## Sources - World Health Organization — To grow up healthy, children need to sit less and play more (2019 guidelines on physical activity, sedentary behaviour and sleep for children under 5) — 14–17 h (0–3 months) and 12–16 h (4–11 months) of good-quality sleep including naps; 11–14 h at 1–2 years: https://www.who.int/news/item/24-04-2019-to-grow-up-healthy-children-need-to-sit-less-and-play-more - Paruthi S et al. Recommended Amount of Sleep for Pediatric Populations — American Academy of Sleep Medicine consensus statement — J Clin Sleep Med 2016 — 12–16 h for 4–12 months, 11–14 h for 1–2 years; no recommendation under 4 months; endorsed by the AAP: https://pmc.ncbi.nlm.nih.gov/articles/PMC4877308/ - Galland BC, Taylor BJ, Elder DE, Herbison P. Normal sleep patterns in infants and children: a systematic review of observational studies — Sleep Medicine Reviews 2012 — 34 studies; nap counts, night wakings and longest sleep by age: https://doi.org/10.1016/j.smrv.2011.06.001 - American Academy of Pediatrics (HealthyChildren.org) — How to Keep Your Sleeping Baby Safe: AAP Policy Explained — Back to sleep for naps and nights, firm flat surface, room sharing for at least 6 months, nothing soft in the sleep space: https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/A-Parents-Guide-to-Safe-Sleep.aspx - American Academy of Pediatrics (HealthyChildren.org) — Getting Your Baby to Sleep — Regular sleep cycles from around 4 months; put babies down drowsy but awake: https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/Getting-Your-Baby-to-Sleep.aspx - NHS — Helping your baby to sleep — Newborn total sleep varies and can be around 18 hours; some 3–6-month-olds sleep 5–8 hours at night, but not all: https://www.nhs.uk/baby/caring-for-a-newborn/helping-your-baby-to-sleep/ - NHS — High temperature (fever) in children — Get urgent advice for a baby under 3 months with a temperature of 38 °C or higher: https://www.nhs.uk/symptoms/fever-in-children/ --- ProbaBaby (listed on the App Store as “Pregnancy & Baby Tracker - PB”) is a free iPhone, iPad and Apple Watch app for pregnancy, newborn and postpartum tracking, built for twins, in 32 in-app languages, with an optional AI baby-face prediction that computes Mendelian genetics (Punnett squares) from the traits you enter before any image is generated. Tracking, tools, PDF reports and family sharing are free; only AI predictions use credits — 5 starter credits cover your first Scientific prediction — and no subscription is required. Requires iOS 26 or later. Not available on Android.