About Sleep Calculator
We help you sleep better through science, not guesswork.
Why we exist
Too many people wake up groggy, hit snooze three times, and drag themselves through the day. The problem usually isn't how long they sleep — it's when they wake up relative to their sleep cycles.
We built this tool to make sleep cycle math effortless. No sign-up, no app to download, no personal data collected. Just science, instantly.
How it works
Your brain cycles through sleep stages roughly every 90 minutes. Wake up at the end of a cycle — you feel refreshed. Wake up mid-cycle, especially during deep sleep — you feel like you got hit by a truck.
Our calculator does one thing: figures out when your sleep cycles end so you can align your alarm (or your bedtime) with those natural wake windows.
- Each sleep cycle ≈ 90 minutes
- Most adults thrive on 5–6 cycles (7.5–9 hours)
- We factor in ~14 minutes to fall asleep
- You get a set of recommended times — pick what fits your schedule
What we stand for
🔬 Science-backed
Every recommendation is grounded in peer-reviewed sleep research.
🔒 Privacy-first
All calculations happen in your browser. We collect nothing.
🆓 Free, always
The core calculator will always be free. No paywalls, no tricks.
🧑💻 Built for humans
Clear results, no jargon, designed to be used — not admired.
Who we are
We're a small team of sleep researchers, developers, and people who used to be terrible at waking up. We built the tool we wish we'd had years ago.