About Sleep Stack
Most sleep calculators on the internet use the same generic 90-minute cycle math with no scientific backing. Sleep Stack was built to be different — a complete stack of free, science-based sleep tools in one place, from bedtime calculators to sleep debt trackers.
What Makes Us Different
Sleep Science First
Every calculator is built on peer-reviewed sleep research from the National Sleep Foundation, NIH, and leading sleep labs. No generic advice — only evidence-based recommendations.
Always Free
All calculators are completely free to use with no account required. We believe science-backed sleep tools should be accessible to everyone.
Research-Backed
Our sleep cycle calculations are based on published research. We cite our sources and explain the science behind every recommendation.
Privacy Focused
Most tools work entirely in your browser — no data sent to servers. When you do create an account, your data is protected with Row Level Security. We never sell personal information.
Our Tools
Sleep Stack offers a full suite of free calculators: bedtime and wake-up time calculators, sleep debt tracker, nap optimizer, caffeine cutoff timer, shift worker scheduler, baby sleep guide, and a chronotype quiz. All tools are free and require no account.
Contact
Questions, feedback, or partnership inquiries? Reach us at hello@sleepstackapp.com.