About
A free bedtime calculator built on real sleep science.
No accounts. No ads inside the calculator. No data leaving your browser. Just a tool that finally accounts for the chaos of real life.
Why Dozely exists
Most bedtime calculators give you the same generic answer regardless of who you are. They assume an idealized sleeper — no kids, no caffeine, no jet lag, no shift work, no afternoon crash. That's not anyone we know.
Dozely was built around a simple observation: sleep happens in 90-minute cycles, but real life happens in messy ones. We wanted a tool that takes both into account — one that gives you a precise bedtime, but also tells you when you'll actually fall asleep, what tomorrow's energy might look like, and what to do about the things keeping you up.
What makes this different
Real cycle math
We work backward from your wake time using the 90-minute sleep cycle, so you wake during light sleep instead of mid-cycle deep sleep.
Personalized for you
Caffeine after 2 PM, young kids, shift work, jet lag, and how tired you feel right now all shift the math. We use them.
Energy forecast
We tell you what tomorrow will feel like — not just when to go to bed, so you can plan a demanding day or take it easy.
Genuinely private
Everything runs in your browser. We don't store your wake time, age, energy level, or any other input on a server. Nothing leaves your device.
Instant & free
No sign-up, no email gate, no paywall. Open the page, get your bedtime in five seconds.
Evidence-based
Sleep duration recommendations align with the National Sleep Foundation and American Academy of Sleep Medicine guidance.
The science we rely on
Sleep isn't a flat state — your brain cycles through four stages roughly every 90 minutes: light sleep (N1), deeper light sleep (N2), deep sleep (N3, also called slow-wave sleep), and REM. The cycle repeats 4 to 6 times per night, with deep sleep dominating the first half and REM dominating the second half.
The reason "8 hours" is somewhat arbitrary: waking up at the wrong point in a cycle can leave you feeling groggier than waking up after fewer hours but at the end of a cycle. This is called sleep inertia. Dozely calculates bedtime to land your alarm at the end of a cycle — usually during light sleep — so you wake feeling sharp.
For the curious, we recommend the work of Matthew Walker (Why We Sleep), Andrew Huberman's sleep protocols, and the National Sleep Foundation's peer-reviewed recommendations for hours of sleep by age.
Who builds Dozely
Dozely is built by a small independent team that cares about quality web tools and respecting your time. We don't have venture funding pushing us to build features nobody asked for. We don't sell data. We don't have a "Pro" tier locked behind a paywall.
The site is monetized by unobtrusive Google AdSense placements that keep it free for everyone. That's it.
Not medical advice
Dozely is a planning tool, not a clinical resource. If you have ongoing sleep problems — chronic insomnia, sleep apnea symptoms, severe daytime fatigue, or anything that's affecting your quality of life — please talk to a doctor. The best calculator in the world can't replace a proper medical evaluation.