Posture Break Reminder Calculator

This builds a break schedule for a working day, using the intervals that occupational health research actually supports, and tells you what each kind of break is for. Three different breaks are doing three different jobs, which is why one reminder every hour does not cover it.

The three intervals

These are the intervals for a sitting or sit-stand desk. A standing desk shifts two of them, for reasons covered further down.

The eye break is the 20-20-20 rule: every 20 minutes, look at something about 20 feet away for 20 seconds. It exists because near focus is a sustained muscular contraction, and 20 feet is far enough that the eye relaxes to nearly its resting state.

The movement interval is the one people get wrong. The evidence supports breaking up sitting roughly every 30 minutes, not every hour. Studies interrupting sitting at 30-minute intervals show measurable improvements in postprandial glucose and blood pressure that hourly interruptions do not reliably produce.

Why sitting specifically

Nachemson’s classic disc-pressure measurements give the mechanism. Taking standing as 100%:

Sitting is worse than standing for the lumbar spine, and slouching is worse again. Two minutes of standing or walking resets the load; you do not need a long break to get the mechanical benefit.

Standing desks are not the answer on their own

A standing desk trades one static posture for another. Standing all day brings its own problems: leg and foot fatigue, and a raised risk of varicose veins with prolonged static standing. That is why the schedule for a standing desk in this calculator has shorter long-break intervals than the sitting one. The goal is not to stand, it is to change position often.

The sit-stand combination scores best because alternating is the actual mechanism, not the height of the desk.

What the calculator counts

Long breaks and movement breaks land on the same clock minute sometimes: at the two-hour mark you are due both. The calculator counts that minute once, as the longer break, rather than adding both. Getting this wrong is how a schedule ends up claiming nearly two hours of breaks in an eight-hour day.

Micro-breaks of 30 seconds, rolling the shoulders or standing to change position, are worth taking on top of all of this and are too short to schedule. Take them whenever you notice you have not moved.