Counts back in 90-minute cycles from your wake-up time, or forward from your bedtime.
How it works
Enter your numbers and the tool does the arithmetic, showing each step so you can check it. Results are rounded sensibly and include the safety limits that apply.
Questions
Is this free?
Yes. The tool is free, needs no sign-up and nothing you enter is stored with your name or email.
Is this medical advice?
No. It is educational information. Talk to a doctor, pharmacist or other qualified professional about any health condition, pregnancy, breastfeeding or medicines.
Can I take it again?
Yes, change any number and work it out again as often as you like.