For planning bedtimes and alarms
Sleep Calculator
Estimate bedtimes or alarm times using 90-minute sleep cycles and a gentle assumption about how long it takes to fall asleep.
Best for
I want a quick estimate for when to go to bed or when to wake up.
Method
Sleep cycle timing estimate
Why it may help
A simple timing estimate can be useful when you are deciding when to get in bed or when to set an alarm, without needing a complicated app.
Night use
Start the tool first. Read the rest later if you want. The dim and black-screen controls will appear inside the session.
30 sec
Sleep calculator
This is a planning tool, not a promise. It uses 90-minute cycle estimates and assumes about 15 minutes to fall asleep.
Start with
For about 9 hours of sleep
9:45 PM
6 sleep cycles + about 15 minutes to fall asleep
For about 7.5 hours of sleep
11:15 PM
5 sleep cycles + about 15 minutes to fall asleep
For about 6 hours of sleep
12:45 AM
4 sleep cycles + about 15 minutes to fall asleep
Planning tomorrow's bedtime around a wake-up time
Choosing a less abrupt alarm time
A quick estimate without tracking or logging data
Related reading
Learn the problem behind the symptom.
Blog article
Best Sleep Tools for Middle-of-the-Night Wakeups
If you keep waking in the middle of the night, the most helpful sleep tool depends on what happens next: spiraling thoughts, body tension, or needing a neutral anchor.
Blog article
Tired but Wired at Night: Why It Happens and What to Do
Exhausted but somehow alert at bedtime? Learn why you can feel tired but wired at night, and which calming sleep tools are most useful in that state.
FAQ
Questions people ask before trying this tool.
Does this calculator know how much sleep I personally need?
No. It is a simple estimate based on 90-minute cycles and a rough fall-asleep window. Your own sleep timing may vary.
Should I use this in the middle of a stressful night?
Usually this works best for planning, not for intense 3AM clock-watching. If you are already spiraling, a calming tool is often a better first move.
Important
This is support for a hard night, not a promise of sleep.
These tools are designed for rough nights, bedtime worry, and temporary wakefulness when you need something gentle and immediate.
They are not medical treatment and they will not solve every kind of sleep problem. If sleep trouble is frequent, severe, or lasting for months, it is worth talking to a clinician.