Free, no sign-up
Sleep tools
Small tools for the practical parts of sleep. Each one shows its arithmetic and cites what it is based on, because a calculator that hides its assumptions is just a confident guess.
Sleep Calculator
Pick a wake-up time or a bedtime and count through full sleep cycles to a realistic window at the other end.
Caffeine Cutoff Calculator
Enter your bedtime and see when to switch to decaf, based on how long caffeine actually lingers in the body.
Breathing Pacer
A visual guide for 4-7-8, box, and coherent breathing — follow the circle, slow your breath, wind down for bed.
Tonight's Sky
The real sky tonight: the constellation the moon is in, its phase, and the constellations overhead right now.
More from Slumber Studios
Two of our sleep tools are big enough to live on their own sites. Both are free, both start with one tap, and neither asks you to sign up.