Wake window calculator

A wake window is the time between your baby waking up and their next sleep. This calculator takes your baby's age and the time they woke up, then shows a range for when to start winding down for the next nap. It's a practical guide for parents of babies and toddlers up to age three, not a medical rule.

Date of birth

Wake-up time

Calculate

What you enter isn't sent anywhere and isn't saved.

How to use the calculator

1. Enter the date of birth. The calculator works out the age in months and picks the right row.
2. Enter the wake-up time. That's when your baby woke up from the night or from the last nap.
3. Check the range. The start of the range is when you can begin winding down: dim the lights, switch to quiet play. The end is the point after which settling often gets harder.

If your baby is clearly tired before the range starts, put them down earlier. Sleepy cues beat the clock.

Wake windows by age

These numbers are the starting points used in Estrelu's sleep forecast. Your baby's window may be shorter or longer, and that's fine.

Many parents notice the first window of the morning is shorter and the last one before bedtime is longer. Watch your baby: yawning, eye rubbing and staring off often tell you more than the clock.

Where these numbers come from

There is no official standard for wake windows. We found no chart of how many minutes a baby should stay awake in WHO, AAP or AASM materials. Wake windows are a practical tool that grew out of the experience of parents and sleep consultants.

The official science gives a different anchor: total sleep per day. The American Academy of Sleep Medicine recommends (AASM, 2016):

• 4 to 12 months: 12 to 16 hours per 24 hours, including naps;
• 1 to 2 years: 11 to 14 hours;
• 3 to 5 years: 10 to 13 hours.

The AASM makes no recommendation for babies under 4 months, because sleep varies so much at that age. The American Academy of Pediatrics notes that newborns sleep about 16 to 17 hours a day (AAP HealthyChildren).

Estrelu's wake window chart is our practical starting point, not a standard and not a calculation from these recommendations.

When the chart won't fit

Off days. Illness, vaccines, teething, a developmental leap or travel can make your baby tire faster or fight sleep. Don't chase the window at all costs.

Dropping a nap. When your baby goes from three naps to two, or two to one, windows jump and for a while no number fits. See our guide to the 2 to 1 nap transition.

Premature babies. Count age from the due date, not the birth date. Ask your pediatrician how long to use adjusted age.

Short naps. After a short nap, babies often get tired sooner than after a long one.

How to make the forecast personal

The chart is the same for everyone, but your baby isn't. Estrelu starts with age-based guides, then adapts to your baby's own logs after a few days.

The next nap shows as a range with a confidence level: low, medium or high. Tap it to see what the estimate is based on. You can get a notification 15 minutes before the window and when it opens. If your baby is sick, mark an "Off day": the forecast won't learn from it and shows a wider range.

Learn more on the sleep tracker page. Flying soon or facing a clock change? Try the time change planner.

If you're not sure, maybe the list of wake window intervals is useful to you, feel free to try it out. But don't worry if it doesn't work for your child.

When to call your doctor

Talk to your pediatrician if your baby is very sleepy and hard to wake for feeds, barely sleeps and is unsettled most of the time, snores or pauses in breathing during sleep, or if sleep changes suddenly along with fever, refusing feeds or other signs of illness.

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Estrelu is not a medical device. It does not diagnose, calculate doses or replace advice from your doctor. This calculator is for general information only.