Start from a planned bedtime
What time should I wake up?
Enter when you plan to go to bed and compare a few estimated wake-up windows.
Worked example
Sleep at 11:30 PM with 15 minutes to settle
The calculator first adds the 15-minute settling estimate, then counts cycles from about 11:45 PM. That gives 4:15 AM, 5:45 AM, 7:15 AM, and 8:45 AM for 3 through 6 approximate cycles.
If you mean this exact moment rather than a planned time, use the sleep-now calculator.
Limits
Cycle timing cannot predict your morning
The calculation simplifies sleep into equal planning blocks. If you fall asleep 20 minutes later than the estimate, every result is 20 minutes early; if you wake during the night, the tool does not know that either.
Read the full methodology.
Questions, answered softly
How does the wake-up calculator work?
It adds your estimated fall-asleep time and 3, 4, 5, or 6 approximate 90-minute cycles to the bedtime you choose.
Can I use the current time instead?
Yes. The sleep-now calculator uses your device's current local time without making you enter it.
Is waking after a full cycle guaranteed to feel better?
No. Sleep timing is variable, and a cycle estimate cannot predict exactly how you will feel.