Sleep Time Calculator
Estimate bedtime from wake-up time and sleep cycles, or wake-up time from bedtime.
Sleep Time Result
Recommended bedtime
23:15
Expected wake-up time
06:45
Sleep duration
7h 30m
Sleep Cycle and Bedtime Calculator
The sleep time calculator estimates bedtime and wake-up time using adjustable sleep cycle length and time to fall asleep.
Sleep Time Calculation Guide
Bedtime From Wake-Up Time
Choose your wake-up time, sleep cycle count, cycle length, and time to fall asleep to estimate a practical bedtime.
Wake-Up From Bedtime
Start with bedtime and add the selected cycle length to estimate when a full-cycle wake-up may happen.
Adjust for Personal Rhythm
90 minutes is a useful default, but many people need a slightly shorter or longer cycle length.
Adult Sleep Planning
Adults often plan around 7 to 9 hours, but workload, exercise, and stress can shift personal sleep needs.
Student Sleep Schedules
When school or exam wake-up time is fixed, checking bedtime first can make the sleep target easier to plan.
Cycle Length Comparison
Try 80, 90, and 100 minute cycles to see how recommended bedtime changes for the same wake-up time.
Sleep Time Calculator FAQ
Is one cycle always 90 minutes?
90 minutes is the default, but you can adjust it for personal variation.
Can I include time to fall asleep?
Yes. Preparation time is subtracted from the recommended bedtime.
Is this medical advice?
No. It is a planning tool; speak with a professional for sleep or health concerns.