An interval is the awake time from waking until the next sleep starts. It is different from nap length. You do not need to guess a number to use this page.
Leave with a useful record, even without a time estimate
Record the last wake time you know. Mark other times as unknown if needed.
Record whether a nap happened, was tried without sleep, or was not offered. Keep these different.
Save what you have for yourself or another caregiver. Add the next actual sleep when it happens.
A missed nap by itself cannot choose a new bedtime. Keep following any existing care instructions; use the guide to review your situation rather than inventing an interval.
We add your interval to the last recorded wake time. With ranges, the earliest wake plus the shortest interval gives the earliest result; the latest wake plus the longest interval gives the latest result. Later planned naps use your assumed duration, so uncertainty can widen.
Trying to settle without sleep and not offering a nap do not reset the wake time. Unknown times remain unknown. A plan never becomes a recorded event just because its time has passed.
These calculations do not determine when a baby will sleep, recommend a nap transition, or diagnose a sleep problem. No age-based rules are approved in this version. Follow any professional care plan and seek professional advice for health concerns or persistent difficulties.
Method and sources
Current method: user-defined interval arithmetic, version 1. No medical review is claimed. For general sleep and care information, see American Academy of Pediatrics: baby sleep. That resource is not used to derive an individual wake interval.
The age pages help you find and organise a day. Their labels do not select an interval, alter your saved age or provide an approved age-based rule.
What is a wake window?
A wake window is elapsed time from waking until the next sleep. A failed sleep attempt and a nap not offered are separate events; neither invents a new wake time.
How this comparison works
We add the interval you enter to the last known wake time. For estimated times, the earliest wake plus the shortest interval gives one end of the range; the latest wake plus the longest interval gives the other.
Choosing your inputs
Choose your own interval and keep following any professional care plan. The calculator does not infer a suitable interval from age, short naps or behaviour. You can record a day without calculating a next nap.
When the day changes
Update what actually happened and compare again. Planned times never become facts automatically. A missing wake time stays unknown; an estimate remains a range.
A wake window is the time between waking and the next sleep. Here, you enter an interval to compare with an actual wake time; the tool does not decide how long your baby should stay awake.
How do I know the right wake window for my baby?
This calculator does not choose a suitable interval from age, nap length or behaviour. Enter the interval you want to compare, or keep recording what you know without requesting a plan.
Comparisons use the settings you entered. A range describes a scenario and does not predict when your baby will fall asleep.