Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
9 hrs sleep — bed at
21:46
7.5 hrs sleep — bed at
23:16
6 hrs sleep — bed at
00:46
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter wake time (hh:mm, 24h).
- 2Enter mins to fall asleep.
- 3Read your 9 hrs sleep — bed at on the right — it updates as you type.
- 4Hit Share to keep the scenario or send it to someone.
About this calculator
Sleep happens in ~90-minute cycles. This suggests bedtimes that end on a cycle boundary so you wake refreshed.