A browser timer cannot assess oxygen levels, supervise breath-holding or determine a safe duration. Watching a countdown is not a reason to resist the urge to breathe.

A practical way to use the display

Use this tool for ordinary activity windows such as a reading session or a rest break. It is not designed as safety equipment for diving or breath-holding practice, and this page provides no training targets.

Open the timer

Use the free visual timer to set minutes and seconds, pause or stop, and choose the display and alarm settings. Keep the tab open and the device awake while timing.