Use this sleep calculator to estimate when to get into bed for a chosen wake-up time, or when to wake after a planned bedtime. It uses adjustable cycle and sleep-onset estimates as a planning guide.
Important: Sleep cycles differ from person to person and can vary from night to night. These estimates are not a medical recommendation or a substitute for advice from a qualified health professional.
Calculate bedtime or wake-up time
Choose a wake-up time to estimate bedtimes, or enter a bedtime to see possible wake-up times.
Choose your time and select “Calculate times” to see estimates.
These are approximate planning estimates, not medical advice. Sleep-cycle length varies between people and from night to night. A calculator cannot diagnose or treat sleep problems.
How to use the sleep calculator
- Choose whether you have a target wake-up time or bedtime.
- Enter the time you plan to wake up or go to bed.
- Adjust the minutes-to-fall-asleep and cycle-length estimates if you prefer.
- Select Calculate times to compare four, five, and six estimated cycles.
How the estimates are calculated
For a target wake-up time, the calculator counts backward by four, five, or six estimated cycles and subtracts your sleep-onset allowance to suggest when to get into bed. For a planned bedtime, it adds the sleep-onset allowance and the selected number of cycles to estimate wake-up times.
Are 90-minute sleep cycles exact?
No. The 90-minute value is a convenient estimate, not a fixed biological timer. Actual sleep cycles vary, so use the results only to help plan a routine. Getting enough regular sleep is more important than matching an exact cycle time.
Frequently asked questions
How many cycles does the calculator show?
It compares four, five, and six estimated cycles. The results are examples, not a personalized sleep prescription.
Can I change the time it takes me to fall asleep?
Yes. The default is 15 minutes, and you can adjust it from 0 to 60 minutes.
Does this calculator diagnose sleep problems?
No. It is a basic planning tool. If you have ongoing difficulty sleeping or daytime symptoms, consider speaking with a qualified health professional.
Want more guidance? Read our sleep cycle calculator guide.
For general planning only. Individual sleep needs vary.