Free tool
Wake window calculator
Enter your baby's age to see their typical wake window — the stretch of awake time between sleeps. Add the time they last woke up and we'll estimate when the next nap is likely. Born early? Use the adjusted-age field. The full wake windows by age chart is below.
Enter your baby's age to see their typical wake window.
Wake windows by age chart
These are the age-based baselines Cradlo's NapCast prediction starts from on iOS, Android, and web. For babies born early, read the chart at their adjusted age.
| Age | Typical wake window |
|---|---|
| 0–6 wk | 45m – 1h |
| 6–12 wk | 1h – 1h 30m |
| 3–4 mo | 1h 15m – 1h 45m |
| 4–6 mo | 1h 30m – 2h 15m |
| 6–9 mo | 2h – 3h |
| 9–12 mo | 2h 45m – 3h 30m |
| 12–18 mo | 3h 15m – 4h 30m |
| 18–24 mo | 4h – 6h |
| 24+ mo (rest time) | 4h – 6h |
How to use wake windows
- Start counting from the moment your baby wakes up, not from the end of a feed.
- Aim to start the wind-down near the low end of the range and have baby asleep before the high end.
- Sleepy cues beat the clock: eye rubbing, ear pulling, zoning out, and fussing usually mean the window is closing.
- The first wake window of the day is often the shortest, the last one the longest.
- If naps are consistently short or bedtime is a battle, try stretching or shrinking the window in 10–15 minute steps for a few days before changing anything else.
Stop doing nap math
This page uses age-based averages. Cradlo's NapCast learns your baby's actual rhythm from the naps you log and predicts the next one automatically — shared live with your partner, grandparents, and daycare.
Try Cradlo freeFrequently asked questions
What is a wake window?
A wake window is the time your baby is awake between one sleep and the next — measured from the moment they wake up to the moment they fall asleep again. Keeping wake windows in an age-typical range helps you time naps before your baby gets overtired.
Are wake window ranges exact?
No. They are typical ranges, not rules. Some babies consistently run shorter or longer than the chart. Use the range as a starting point, watch your baby's sleepy cues (eye rubbing, zoning out, fussing), and adjust in 10–15 minute steps.
Should I use adjusted age for a premature baby?
Yes. If your baby was born early, count their age from the due date rather than the birth date when using age-based sleep ranges. The “born early” field in this calculator does that adjustment for you.
When do babies drop to one nap?
Most babies consolidate from two naps to one somewhere between 12 and 18 months, and naps often become optional after age two — many families switch to a quiet rest time instead. Follow your child's mood and night sleep rather than the calendar.
Where do these ranges come from?
They are the age-based baselines that Cradlo's NapCast prediction starts from. In the app, NapCast then personalizes the window to your baby using the naps you actually log — the more you log, the closer the prediction gets to your baby's real rhythm.
Is this medical advice?
No. This calculator is general information for healthy babies and is not medical advice. If you have concerns about your baby's sleep, growth, or development, talk to your pediatrician.
This tool provides general information for healthy babies and is not medical advice. See our disclaimer.