What is a sleep calculator?
A sleep calculator estimates good bedtimes or wake-up times by counting 90-minute sleep cycles and comparing the total sleep window with age-based sleep recommendations.
Bedtime and wake-up planner
Free Sleep Calculator
A sleep calculator is a free online tool that estimates good bedtimes or wake-up times by counting 90-minute sleep cycles, fall-asleep time, and age-based sleep needs.
90-minute sleep cycle planner
Set your sleep goal
Choose the time you already know, then compare sleep-cycle options against the recommended range for each age group.
Adult sleep range
7-9 hours
Most adults feel best with 5 or 6 full sleep cycles.
Best match
Try bedtime
9:45 PM
6 sleep cycles, about 9 hr asleep, plus 15 minutes to drift off.
Suggested bedtimes
6:45 PM
8 cycles - 12 hr
8:15 PM
7 cycles - 10 hr 30 min
9:45 PM
6 cycles - 9 hr
11:15 PM
5 cycles - 7 hr 30 min
12:45 AM
4 cycles - 6 hr
2:15 AM
3 cycles - 4 hr 30 min
Frequently Asked Questions
How many sleep cycles should I get?
Most adults aim for 5 or 6 full 90-minute cycles, which is about 7.5 to 9 hours asleep. Children and teens usually need a longer total sleep window.
What time should I go to bed if I wake up at 7 AM?
For a 7 AM wake-up, many adults should consider bedtimes around 9:45 PM or 11:15 PM if they need about 15 minutes to fall asleep. The better choice depends on your age and sleep need.
Is waking up between sleep cycles better?
Waking near the end of a sleep cycle may feel easier because you are less likely to wake from deeper sleep. It is still more important to get enough total sleep consistently.
Can this replace medical sleep advice?
No. This calculator is for planning routines. Talk with a clinician if sleep problems are persistent, severe, or connected to breathing, mood, medication, or daytime safety concerns.
Related Tools
Baby Sleep Schedule Generator
Create age-appropriate baby and toddler sleep schedules with wake windows and naps.
Screen Time Calculator
Plan family media limits and activity swaps that protect sleep and routines.
Family Meeting Agenda Generator
Build a quick agenda for aligning bedtime routines, chores, and weekly plans.