Free sleep tools that admit what they cannot know.
Four small calculators for the questions tired people actually ask. Each one shows its sources and its limits, runs in your browser and stores nothing.
Bedtime & wake-up
Sleep calculator
A window for enough sleep, then cycle times as a rough guide.
Open toolCaffeine timing
Caffeine calculator
Caffeine left at bedtime, and a research-based cut-off time.
Open toolBody clock
Chronotype calculator
Your social jet lag and a chronotype marker from real sleep times.
Open toolRecovery
Sleep debt calculator
Add up a week of short nights against your own sleep need.
Open toolStart here
A calculator answers one question. The quiz helps you pick the right one.
The free Mismatch Quiz is an educational starting point, not a diagnosis. It takes about 4 minutes and shows one pattern worth investigating.