Wake Window Calculator — Next Nap & Bedtime by Age

Who this is for: For parents of babies 0–36 months who keep asking "should my baby be asleep already?" — especially during regressions and nap transitions, when yesterday's timing suddenly stops working.

Pick your baby's age, enter when they woke up, and get the wake-window range plus the clock times for the next nap and bedtime.

Quick answer: A wake window is how long a baby can stay awake between naps: 35–60 minutes for newborns, 60–90 minutes at 3 months, 2–3 hours at 6–12 months, and 4–5 hours by 18 months. Enter your baby's age and wake-up time below to get the next nap window and bedtime in clock time.

Baby's age

Baby woke up at

Accepts 7:05 AM, 7:05 pm, or 19:05.

Wake window

1 h 15 min–1 h 45 min

4 months · typical range

Next nap — window opens

8:15 AM

after 1 h 15 min awake

Next nap — window closes

8:45 AM

past this, overtiredness builds

Bedtime rule: last nap end + this age's final window (1 h 45 min) — the bedtime calculator works it out for you. This is general guidance for 4 months — sleep cues (yawning, staring, rubbing eyes) outrank the clock.

Core facts

Age range covered	0–36 months
Outputs	Window range + next nap + bedtime (clock times)
Inputs	Age + last wake-up time (or last nap end)
Compiled	September 2026

What does this wake window calculator tell you?

A wake window is how long a baby can comfortably stay awake between sleep periods — too short and they fight the nap, too long and cortisol makes falling asleep harder. This calculator takes your baby's age and the time they last woke up, then returns the typical window range for that age and turns it into clock times: when the next nap window opens, when it closes, and a bedtime suggestion for the end of the day. The ranges are compiled from widely used pediatric sleep resources; your baby's own sleep cues always outrank the clock.

Common uses

Working out when the next nap should start after a short or long wake-up
Checking whether the current fussiness is tiredness or just a wide-awake baby
Resetting the day after a nap that ended far too early
Sanity-checking the schedule a sleep app or consultant gave you

Where these ranges come from

Ranges are compiled in September 2026 from widely used pediatric sleep resources (Huckleberry sample schedules, Taking Cara Babies, Full Feedings and similar). Sources disagree by ±15 min at the edges — treat the range, not one number, as the target and watch your baby's sleep cues.

Frequently Asked Questions

What is a wake window?

The stretch of time a baby stays awake between two sleep periods — from when they wake until they're back to sleep. Newborns manage 35–60 minutes; toddlers can go 5 hours. Exceeding the window regularly builds overtiredness, which makes naps and bedtime harder, not easier.

Should I use the start or the end of the range?

Use the start of the range on a normal day, and lean toward the end if your baby fought the last nap, woke early, or shows strong tired signs late in the window. The last window of the day is usually the longest.

Does the wake window start when my baby wakes or when the nap ended?

When they actually wake up. If your baby wakes 20 minutes into a nap, the window starts from that early wake — which is why a short nap so often produces a fussy, overtired afternoon.

Do wake windows include feeding time?

Yes — the window covers everything while awake: feeds, play, diaper changes, wind-down. The wind-down routine (10–15 minutes) happens inside the window, so start it before the window closes.

Is this a medical recommendation?

No. This is general guidance compiled from major pediatric sleep resources as of September 2026. Every baby differs, and persistent sleep problems deserve a chat with your pediatrician.

More wake window calculators

Nap Schedule Generator

Enter your baby's age and wake-up time — get a full-day nap schedule with clock times for every nap and bedtime.

Baby Bedtime Calculator

Enter your baby's age and the time the last nap ended — get the bedtime window that fits the age's final wake window.

3-Month-Old Wake Windows

3 months: wake windows 1 h–1 h 30 min, 4–5 naps, 14–16 h total sleep. Calculator preset to this age.

4-Month-Old Wake Windows

4 months: wake windows 1 h 15 min–1 h 45 min, 3–4 naps, 14–15 h total sleep. Calculator preset to this age.

5-Month-Old Wake Windows

5 months: wake windows 1 h 30 min–2 h 15 min, 3 naps, 13.5–14.5 h total sleep. Calculator preset to this age.

6-Month-Old Wake Windows

6 months: wake windows 2 h 15 min–2 h 45 min, 2–3 naps, 13.5–14.5 h total sleep. Calculator preset to this age.