Sleep tools for better schedules.

Why SleepTools exists

I built SleepTools because I wanted a bedtime calculator that actually understood sleep cycles — not one that just added up hours, but one that calculated the right moment to fall asleep so that waking up doesn't feel like surfacing from concrete. That specific tool didn't exist in a clean, free, dedicated form. So I built it.

Then I wanted a sleep debt tracker that showed recovery time, not just a deficit number. Then a caffeine cutoff calculator that modelled half-life properly. Then a baby sleep tool that gave real wake windows and sample schedules, not just a vague age range. Every calculator on this site was built to answer a specific question someone actually searches for.

What makes these calculators different

Most sleep calculators add up hours and call it done. SleepTools calculators are built around how sleep actually works:

• Sleep cycles are 90 minutes — waking at the end of a cycle feels fundamentally different from waking mid-cycle.
• Sleep debt accumulates and has a recovery rate — knowing your deficit matters less than knowing how long recovery takes.
• Caffeine half-life varies by sensitivity — a normal metaboliser and a slow metaboliser have different cutoff times for the same bedtime.
• Baby sleep needs change every few weeks — a 4-month schedule is completely different from a 6-month schedule.
• Shift worker sleep isn't just “sleep when you can” — there's a circadian model behind the best recovery windows.

All tools are free, no account required. The site is supported by display advertising, which is what keeps the calculators free to use and maintain.

Sources and accuracy

Sleep need recommendations come from the National Sleep Foundation and CDC guidelines. Sleep cycle models are based on established circadian rhythm research, using the standard 90-minute cycle with a 14-minute average sleep onset latency. Caffeine half-life values use the published pharmacokinetic range (5–9 hours depending on metaboliser type). Baby sleep schedules are cross-referenced against NSF, AAP, and Huckleberry guidelines.

Every formula is extracted into a separate, independently tested library. If you find a result that doesn't match your experience, the most likely cause is a difference in individual sleep cycle length or metaboliser type — both of which are adjustable in the relevant calculators.

These tools are for informational purposes only and are not a substitute for medical advice. For sleep disorders or health concerns, consult a healthcare provider.

Get in touch

Questions, corrections, or calculator requests: hello@sleeptools.co

If SleepTools has been useful, the best thing you can do is share it with someone who would benefit — a new parent, a shift worker, or anyone who sets three alarms and still wakes up feeling wrecked.