Wake Window Calculator
Move the slider to your baby's exact age — in months, not vague age bands — and get a complete nap schedule instantly. Free, no signup, no popups, works one-handed at 3am.
Today's schedule
How the calculator works
A wake window is the stretch a baby can stay comfortably awake between sleeps. Our engine holds published pediatric ranges for each age — then does what paper charts can't: it interpolates continuously. A 17-week-old is not the same as a 21-week-old, and the slider treats them differently while every other tool lumps both into "4–6 months".
The schedule also shapes the day the way real babies live it: the morning window runs a little shorter (≈85% of the base), the final window before bed runs longer (≈115%), and daytime sleep is distributed across naps with the first nap usually the longest. If a nap runs short, tick "Last nap was short" and the next window shrinks — because a baby who slept 30 minutes instead of 90 will not last a full window.
Two directions, one tool: build forward from wake-up on free days, or lock bedtime and let the schedule fit itself backwards between wake-up and your target — the daycare-nights mode no other free calculator offers.
What makes this calculator different
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Exact age, not bands
Set age in months and weeks — windows interpolate continuously instead of jumping at 4–6 month labels.
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Instant results
The schedule is on screen before you finish reading this sentence. No 'Calculate' button, no reload.
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Bedtime lock
Fixed bedtime? The tool works backwards from it and tells you honestly when naps don't fit.
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Short-nap recovery
Real babies take 30-minute naps. The schedule adapts the next window instead of assuming a perfect day.
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Print, copy, calendar
One tap prints a clean schedule, copies it as text for the family group, or saves naps to your phone calendar (.ics).
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Zero friction, forever
No account, no popup, no email wall, no course pitch — just the tool, in dark mode by default at night.
Wake windows by age — quick chart
The full guide with per-age pages lives at wake windows by age.
| Age | Wake window | Naps | Day sleep |
|---|---|---|---|
| 1 month | 60–75 min | 4–6 | 4–6 hr |
| 2 months | 60–90 min | 4–5 | 4–5.5 hr |
| 3 months | 75–105 min | 4–5 | 3.5–5 hr |
| 4 months | 90–120 min | 3–4 | 3–4.5 hr |
| 5 months | 105–150 min | 3–4 | 2.5–4 hr |
| 6 months | 120–165 min | 3–3 | 2.5–3.5 hr |
| 7 months | 135–180 min | 2–3 | 2–3 hr |
| 8 months | 150–195 min | 2–3 | 2–3 hr |
| 9 months | 150–195 min | 2–2 | 2–3 hr |
| 10 months | 165–210 min | 2–2 | 2–2.5 hr |
| 12 months | 180–240 min | 2–2 | 2–2.5 hr |
| 15 months | 180–240 min | 1–2 | 1.5–2.5 hr |
| 18 months | 240–300 min | 1–1 | 1.5–2.5 hr |
| 2 years | 270–330 min | 1–1 | 1–2 hr |
| 3 years | 300–360 min | 1–1 | 0.5–1.5 hr |
Frequently asked questions
›What is a wake window?
A wake window is the amount of time your baby can comfortably stay awake between two sleeps. Keep them awake past it and cortisol builds up, making it harder — not easier — for them to fall asleep. Wake windows lengthen as babies grow, from about 45–60 minutes in the newborn stage to 5–6 hours at age two.
›How long should my baby stay awake by age?
Rough guide: 1 month old 60–75 minutes, 3 months 75–105 minutes, 4–5 months 90–150 minutes, 6 months 2–2¾ hours, 9 months 2½–3¼ hours, 12 months 3–4 hours, 18 months 4–5 hours. Our calculator interpolates these ranges continuously for your baby's exact age in months and weeks.
›Why does the calculator show different window lengths across the day?
Wake windows are not one fixed number. The first window of the morning is usually the shortest, and the last window before bedtime is the longest. The schedule shapes each window: about 85% of the base window in the morning, rising to about 115% before bed.
›What if my baby takes a short nap?
A short nap (under ~45 minutes) usually means your baby needs a shorter next wake window — they got less restorative sleep and will tire sooner. Tick 'Last nap was short' and the calculator shortens the next window instead of pretending the day went to plan.
›Should I use wake time or a locked bedtime?
If your days start at roughly the same time, build from wake time and let bedtime land where it lands. If bedtime is fixed — daycare mornings, siblings' routines — use Lock bedtime and the calculator works backwards, fitting naps between wake-up and your target bedtime.
›When do babies drop to one nap?
Most babies transition from two naps to one between 13 and 18 months. Signs: consistently fighting the second nap, early-morning wakings returning, or the second nap pushing bedtime too late. Around 15 months our schedule already shows the 1–2 nap transition range.
›Is this medical advice?
No. This tool follows published pediatric sleep guidance ranges (see our methodology) but every baby is different. If your baby consistently sleeps far outside these ranges, or sleep problems persist, talk to your pediatrician.