Free online wake window calculator. No app, no signup.

Ideal wake window

1h 45m to 2h 15m

for a 4 month old

Next nap approx ...

Baby's age

0 3mo 6mo 9mo 12mo 18mo 24mo

Last woke at

Adjust to see the next nap

Naps / day

2 to 3

Day sleep

3 to 4h

Night sleep

10 to 12h

Sample day Example schedule for a 4 month old using the middle of the range.

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Wake windows by age, cues, and how to tune the timing

The tool above does the math. This section answers the questions that come up once you start using it.

Wake windows by age at a glance

Age	Wake window	Naps / day	Day sleep	Night sleep
0 to 6 weeks	45 to 60 min	4 to 6	6 to 8h	8 to 10h (broken)
6 to 12 weeks	60 to 90 min	3 to 5	4 to 6h	9 to 11h
3 to 4 months	75 to 105 min	3 to 4	3.5 to 5h	10 to 12h
4 to 5 months	90 to 120 min	3 to 4	3 to 4h	10 to 12h
5 to 7 months	1h 45m to 2h 30m	2 to 3	2.5 to 3.5h	10 to 12h
7 to 10 months	2h 30m to 3h	2	2 to 3h	10 to 12h
10 to 14 months	3 to 4h	1 to 2	2 to 2.5h	10 to 12h
14 to 18 months	4 to 6h	1	1.5 to 2.5h	10 to 12h
18 to 24 months	5 to 6h	1	1.5 to 2h	10 to 12h

Averages from pediatric sleep guidance. Not medical advice. If you are worried, call your pediatrician.

Signs the wake window is ending

👀

Zoning out

Staring into space or going very still. One of the earliest signs and easy to miss.

🥴

Eye rubs, ear tugs

Classic tired cues. If you see these, you are usually already close to overtired.

🥱

Yawning

Helpful but often late. Use it as confirmation, not a first warning.

😡

Fussy for no reason

Fed, changed, held, still upset. Very often a "please put me down" cue.

🤳

Hyper and clumsy

Older babies get a second wind near overtired. Looks like energy, reads as "get me to bed".

🔇

Suddenly quiet

Babbling stops, engagement drops. The nervous system is saying "I am done".

How wake windows actually work

A wake window is the time your baby spends awake between sleeps. As babies grow, their nervous system can handle longer and longer stretches without falling apart. A newborn often lasts only 30 to 60 minutes before needing to sleep again. A toddler can go most of the day on one short nap.

The goal of timing naps to wake windows is simple. Catch your baby in the sweet spot where they are tired enough to sleep easily, but not so tired that their body releases stress hormones and fights it. Overtired babies take shorter naps, wake more at night, and are harder to settle. Undertired babies fight the nap and resist the bedtime routine.

How to use the calculator

Enter your baby's age. The calculator returns a range, not a single number. Start with the middle.
Type the time your baby last woke up. The tool shows the window for the next nap.
Watch for sleepy cues in the last 10 to 15 minutes of the window. Start the wind-down when you see them.
If naps keep getting shorter, your baby is probably going down overtired. Try the shorter end next time.
If your baby fights sleep and cannot settle, they may be undertired. Try the longer end.

When wake windows don't apply

Sleep regressions, illness, developmental leaps, travel, and newborn cluster days all throw wake windows off. Use the calculator as a baseline and give yourself room to adjust for real life. Wake windows are a tool, not a rule.

Common mistakes

Starting the timer when the nap ends instead of when the baby actually wakes. The window starts the moment your baby opens their eyes.
Waiting for yawns. Yawning is often a late cue. By then you are chasing the nap.
Treating the number as fixed. Wake windows shift during growth spurts and leaps. Re-check weekly.
Ignoring the morning window. The first wake window of the day is almost always the shortest. A longer-than-usual morning window often tanks the whole day.

Is this a replacement for sleep training?

No. Wake windows help you time naps and bedtime. They do not teach your baby to fall asleep independently. You can use wake windows alongside any sleep approach. Contact naps, co-sleeping, cry-free methods, or formal sleep training. They just make the timing part easier.

Privacy

Nothing you type into this calculator is saved or sent anywhere. It all runs in your browser and disappears when you close the tab.

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Want Pippy to watch the clock for you?

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