Bedtime Calculator
Enter your wake-up time and find the best time to go to bed. Aligns your bedtime with the end of a sleep cycle so you wake up refreshed instead of groggy.
Sleep Calculators
Free tools to help you find the right bedtime, wake-up time, and sleep duration. Each calculator is based on 90-minute sleep cycles and recommendations from the National Sleep Foundation.
Wake-Up Time Calculator
Enter your bedtime and find the best alarm times. Calculates optimal wake times for 3, 4, 5, and 6 complete sleep cycles.
Sleep Cycle Calculator
Enter your bedtime and wake time to see how many complete sleep cycles you get. Breaks down time spent in light, deep, and REM sleep.
Sleep Debt Calculator
Track your accumulated sleep debt by comparing how much sleep you need versus how much you actually get. Includes recovery time estimates.
Sleep by Age Calculator
Check if you're getting enough sleep for your age group based on National Sleep Foundation guidelines, from newborns to seniors.
Related Guides by Calculator
Each calculator has companion guides that explain the science behind it and help you make the most of your results.
Bedtime Calculator Guides
Wake-Up Calculator Guides
Sleep Cycle Calculator Guides
Sleep Debt Calculator Guides
Sleep by Age Calculator Guides
More Sleep Resources
Frequently Asked Questions
Use the Bedtime Calculator if you know when you need to wake up and want to find the best time to go to bed. Use the Wake-Up Calculator if you know when you're going to bed and want to find the best alarm time. Use the Sleep Cycle Calculator to analyze how many complete cycles you're getting. Use the Sleep Debt Calculator to track accumulated sleep loss. Use the Sleep by Age Calculator to check if you're getting enough sleep for your age group.
Sleep calculators are based on the science of 90-minute sleep cycles. Each cycle includes light sleep, deep sleep, and REM sleep. Waking up at the end of a complete cycle (rather than in the middle) helps you feel refreshed instead of groggy. The calculators factor in approximately 15 minutes to fall asleep and calculate optimal times aligned with cycle boundaries.
These calculators use the widely-accepted average of 90 minutes per sleep cycle, which is accurate for most adults. However, individual cycle length can vary from 70 to 120 minutes. The calculators provide excellent starting points — you may need to adjust by 15-30 minutes based on how you feel. Factors like age, caffeine intake, and sleep disorders can affect accuracy.
Most adults need 5-6 complete sleep cycles per night, which equals 7.5 to 9 hours of sleep. The minimum before cognitive impairment sets in is typically 4 cycles (6 hours). Teenagers need more (5-7 cycles), while some seniors may function well on 4-5 cycles. The Sleep by Age Calculator provides personalized recommendations.
Yes, the calculators complement each other. For example, use the Bedtime Calculator to find your ideal bedtime, then use the Sleep Debt Calculator to track whether you're consistently hitting that target. Use the Sleep by Age Calculator to verify the recommended duration for your age, then use the Sleep Cycle Calculator to check your cycle count against that recommendation.
No. All five sleep calculators are completely free, run in your web browser, and require no downloads, sign-ups, or personal data. They work on any device — desktop, tablet, or phone.