Baby Sleep Calculator
Wake windows by age
From newborn to toddler, find age-appropriate wake windows, nap counts, and suggested schedules based on pediatric sleep medicine consensus.
The wake-window table
The single most important concept in baby sleep: babies need to be awake for the right amount of time before they can fall asleep well. Too short, and they're not tired. Too long, and they're overtired (which is harder to recover from than mildly undertired).
| Age | Wake window | Naps/day | Total sleep (24h) |
|---|---|---|---|
| 0–6 weeks | 35–60 min | 4–8 | 14–18 hours |
| 6–12 weeks | 60–90 min | 4–5 | 14–17 hours |
| 3–4 months | 75–120 min | 4–5 | 13–16 hours |
| 5–6 months | 90–150 min | 3–4 | 12–15 hours |
| 7–9 months | 2–3 hours | 2–3 | 12–15 hours |
| 10–12 months | 3–4 hours | 2 | 12–14 hours |
| 13–18 months | 4–6 hours | 1–2 | 11–14 hours |
Adapted from AAP and pediatric sleep medicine consensus (Mindell et al., 2009; Sheldon's Principles of Pediatric Sleep Medicine, 6th ed.).
How to read sleepy cues
Wake windows are estimates. Your baby's behavior is the real signal:
- Early cues (catch these): yawning, zoning out, decreased activity, ear or eye rubbing, looking away from stimulation.
- Mid cues: fussiness, clinginess, pulling at hair or ears, eyes glazing over, brief whimpering.
- Late cues (overtired): arching back, hyperactivity ("second wind"), crying that escalates fast, refusing the bottle or breast.
Aim to start the wind-down routine at the early-cue stage. If you're seeing late cues, the next nap or bedtime is already past optimal.
Common mistakes to avoid
- Keeping baby up longer to "tire them out." Overtired babies sleep worse, not better. Stick to age-appropriate wake windows.
- Skipping naps to "force" a longer night sleep. Daytime sleep doesn't trade against nighttime sleep until well into toddlerhood. Skipping naps just creates overtiredness.
- Strict schedules in the first 3 months. Newborns don't have a circadian rhythm yet. Watch their cues, not the clock.
- Bright light during night feeds. Keep night wakings dim, quiet, and boring. Save energy and stimulation for daytime.
- Long late-afternoon naps after 12 months. Cap the late nap so it doesn't push bedtime past 8 PM.
The newborn stage: why there's no schedule yet
If you have a baby under about 12 weeks, the most important thing to know is that a rigid schedule isn't developmentally possible yet. Newborns haven't developed a circadian rhythm, the internal clock that ties sleep to the day-night cycle doesn't mature until around 3 months. Until then, sleep is distributed across all 24 hours in short bursts, driven by hunger and comfort rather than the clock.
What you can do is gently lay the groundwork: expose your baby to bright light and normal activity during daytime feeds, and keep night feeds dark, quiet, and boring. This contrast is the first nudge toward a day-night rhythm. The wake windows in the calculator above become genuinely useful from around 6–12 weeks onward, as patterns start to emerge.
Understanding sleep regressions
Parents often describe sudden stretches where a previously good sleeper falls apart. These "regressions" almost always line up with developmental leaps:
- 4 months: The big one. Your baby's sleep architecture matures into adult-like cycles. This is permanent progress, not a true regression, but it disrupts sleep for 2–6 weeks while the new pattern settles.
- 8–10 months: Crawling, pulling up, and separation awareness disrupt sleep. Often coincides with the 3-to-2 nap transition.
- 12 months: Some babies briefly resist the morning nap (they're not ready to drop it yet, hold the 2-nap schedule).
- 18 months: Language explosion, molars, and growing independence. Often overlaps the 2-to-1 nap transition.
The common thread: resist introducing new sleep crutches during a regression, keep wake windows age-appropriate, and wait it out. Most resolve within a few weeks. For the full developmental picture, see our complete baby sleep guide.
Safe sleep basics
Whatever schedule you land on, the American Academy of Pediatrics' safe-sleep guidance is non-negotiable for babies under one year: always place baby on their back, on a firm flat surface, with no soft bedding, bumpers, or stuffed animals in the crib. These recommendations have cut SIDS deaths by more than half since 1992. This calculator helps with timing, but safe sleep practices come first.
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Frequently Asked Questions
What is a wake window?
A wake window is the maximum time your baby can comfortably stay awake between sleeps. It expands as they grow, from about 45 minutes for newborns to several hours by toddlerhood. Babies kept awake past their wake window often become overtired, which paradoxically makes falling asleep harder, not easier.
How do I know if my baby is overtired?
Classic overtired signs: difficulty falling asleep despite obvious fatigue, fighting naps and bedtime, frequent night wakings, second-wind hyperactivity (acting energetic when they should be sleepy), and crying that's harder to soothe than usual. The fix is usually shortening the wake window, not lengthening it.
What is the "4-month sleep regression"?
Around 3–4 months, your baby's sleep architecture matures from infant patterns (mostly active and quiet sleep) to adult-like cycles with distinct stages. This is permanent, not a "regression" but a developmental milestone. Sleep may temporarily get worse for 2–6 weeks as the new pattern stabilizes. It's a sign things are progressing normally.
When should babies sleep through the night?
"Sleeping through" is typically defined as 5+ hours of unbroken sleep. About 50% of healthy infants achieve this by 5 months; 75% by 9 months. There's wide normal variation. Many factors play in: feeding pattern (breastfed babies often wake more frequently for shorter), individual temperament, and consistent bedtime routine.
Are wake windows the same for every baby?
No, they're population averages. Some babies need significantly shorter windows (especially those who are highly sensitive or going through a developmental leap). Others tolerate longer windows. Watch your baby's sleepy cues, yawning, ear-rubbing, vacant stare, fussiness, and adjust accordingly.
When do most babies drop to one nap?
Between 13–18 months, with significant individual variation. The 2-to-1 nap transition signs include: refusing the morning nap, taking very short naps, bedtime getting pushed later, and night wakings appearing. Move to one nap gradually, alternate between 2 naps and 1 nap days for the first 2 weeks.
Is this calculator a substitute for medical advice?
No. Sleep schedules are individual, and persistent sleep problems can occasionally signal medical issues (reflux, ear infections, sleep apnea, breathing problems). Always consult your pediatrician for ongoing concerns. The calculator is general educational guidance based on pediatric sleep medicine consensus.