Wake-Up Time Calculator
Working backward from bedtime to the smartest alarm time.
Some nights you just need to know: “If I go to bed right now, when should I wake up?” That is what this calculator answers. Enter the time you plan to get into bed, and it uses 90-minute sleep cycles to suggest five ideal wake-up times. The first option gives you six full cycles (nine hours of sleep) - ideal if you are recovering from sleep debt. The middle options give you five or four cycles, which suits most adults on a normal night. The shortest options are for emergency scenarios when you need to be up early. Unlike setting a random alarm, aligning your wake time to the end of a cycle means your body is drifting out of deep sleep naturally when the alarm goes off. That is the difference between feeling foggy for an hour versus feeling clear-headed within a few minutes. The calculator also accounts for the time it takes you to fall asleep, because lying in bed scrolling does not count as sleeping.
The Science
Waking at the end of a sleep cycle - during light REM or NREM - minimizes sleep inertia, the groggy disorientation that follows waking from deep sleep. Studies have shown that sleep inertia can impair cognitive function for up to two hours after waking from deep sleep. Timing your alarm to cycle boundaries reduces this effect.
How It Works
Enter the time you plan to be in bed.
Adjust the fall-asleep buffer if needed.
Pick the wake-up time that fits your schedule - aiming for 5 or 6 cycles when possible.