Health•Free tool
Sleep Calculator – Best Bedtime & Wake Times
Find the best time to go to bed or wake up using 90-minute sleep cycles. Wake up refreshed, not groggy.
No sign-upBrowser-based
HLT
Tool
Enter your values and get results instantly.
HOW
How to Use
- 1Choose your mode — bedtime or wake time\n2. Enter your target time\n3. See the best options based on 90-minute cycles\n4. Pick one that fits
WIN
Benefits
90-minute cycle science
Bedtime and wake modes
Multiple suggestions
Clear fall-asleep buffer
Free and private
FAQ
Frequently Asked Questions
How does the sleep cycle work?
Sleep cycles last about 90 minutes. Waking at the end of a cycle (not mid-cycle) leaves you feeling more rested.
Why add a fall-asleep buffer?
Most people take 15-20 minutes to fall asleep, so the calculator subtracts this from the cycle math.
Is it accurate for everyone?
Cycles vary between 80-120 minutes per person, so treat the result as a helpful guide, not an exact science.