EV-T19Standalone tool

Sleep calculator

Work backward from a wake-up time in 90-minute sleep cycles to compare candidate bedtimes.

EV-T19

Find a bedtime that fits sleep cycles.

Work backward from your wake-up time in complete 90-minute cycles. Cycle length is an average, not a personal measurement.

COMMON WAYS TO ASK

What time should I go to bed?
Sleep cycle calculator
When to sleep to wake at 6

QUICK ANSWER

What this calculator tells you.

Pick your wake-up time and how long you usually take to fall asleep. The tool counts backward in complete 90-minute cycles and shows three candidate bedtimes with the sleep each provides.

WORKED EXAMPLE

Waking at 7:00 AM

INPUTWake 7:00 AM · 15 minutes to fall asleep

RESULT9:45 PM (9 h) · 11:15 PM (7.5 h) · 12:45 AM (6 h)

CHECK THE EDGE CASES

Questions people ask next.

Is every sleep cycle exactly 90 minutes?

No. Real cycles average roughly 90 minutes but vary between people and across the night. The calculator is a planning aid, not a physiological measurement.

How much sleep do adults need?

The CDC advises that most adults need seven or more hours per night. The four-cycle option exists for comparison, not as a recommended routine.