Work out alarm time instantly with clear inputs, formula shown and shareable results.
Set the alarm for the time you must leave minus getting-ready time minus however long you actually spend snoozing. Being honest about the snooze habit is the point: nine minutes times three is nearly half an hour of fragmented, low-quality sleep.
Alarm time
alarm = leave time - preparation time - (snoozes x snooze interval)
A quirk of mechanical clock gearing that became a convention, and digital clocks kept it for familiarity.
It fragments the last sleep cycle and can worsen grogginess. Setting the alarm for the real getting-up time gives better quality sleep in the same window.