A simpler, more transparent sleep calculator

Sleep Calculator is a free browser-based planning utility for estimating bedtime and wake-up windows.

Why it exists

Many sleep calculators present a single 90-minute assumption as if every person's sleep follows an exact timer. This project keeps the convenience of cycle-based planning while exposing the assumptions and allowing them to be adjusted.

Privacy-first calculation

The flagship calculations run in your browser. No account is required for ordinary use.

What it is not

It is not a medical device, sleep-stage monitor, diagnostic service or substitute for healthcare advice.