Sleep Cycle Calculator
Time & Date · Free Online Tool
Recommend bed/wake times based on 90-minute sleep cycles.
Wake at
03:15
3 cycles · OK
4.5h sleep
Wake at
04:45
4 cycles · Good
6h sleep
Wake at
06:15
5 cycles · OK
7.5h sleep
Wake at
07:45
6 cycles · Optimal
9h sleep
90-min Cycles
Based on the average 90-minute sleep cycle length.
Both Directions
Plan from bedtime or from a target wake time.
Fall-asleep Buffer
Includes 15 minutes to drift off.
How to Use Sleep Cycle Calculator
- 1Enter the time, date, or value you want to convert.
- 2Select the target format or timezone.
- 3The tool calculates the result instantly.
- 4Copy the converted value for your use.
Features
- ✓100% free — no signup, no subscription, no ads
- ✓Runs entirely in your browser — data never leaves your device
- ✓Fast and lightweight — instant results
- ✓Cross-platform — works on desktop, tablet, and mobile
Frequently Asked Questions
What timezone is used by default?
The Timestamp Converter uses UTC by default but can display results in your local timezone.
Can I convert timestamps from different programming languages?
Yes, the tool supports Unix timestamps (seconds and milliseconds), ISO 8601, and various date string formats.
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Learn the concept
Learn the concept
Understand the programming ideas behind this tool.