Hourglass Timer

The hourglass shows time as sand: the top chamber empties and the bottom fills at exactly the rate of the countdown, so the remaining time is visible as a proportion rather than a number. That makes it the easiest timer to read at a glance, from across a room, or for a child who cannot yet read a clock. Choose a preset from 1 to 30 minutes or enter any length; the animation is computed from the real clock, so it stays accurate even if the tab is in the background, and a soft chime marks the end.

• Young children. "When the sand runs out" is concrete; "in five minutes" is not. Use it for tidying up, screen time and turn-taking.
• Board games. Many games ship with a 30, 60 or 90-second sand timer that eventually gets lost. Set the same length here and put the tablet in the middle of the table. The board game timer covers per-player turns.
• Meditation and breathing. Watching sand fall is itself calming; the meditation timer adds interval bells if you want them.
• Classrooms. A visible drain on a projector settles a class faster than a spoken warning; the classroom timer is the same idea with colour bands.
• Speaking practice. A one-minute hourglass for a mini-talk, without the pressure of a ticking number.

Sand glasses appear in European records from the fourteenth century, first at sea, where a pendulum clock is useless on a rolling deck. Ships used a half-hour glass to mark the watches, turning it at each run-out and ringing the bell, which is where the naval "eight bells" system comes from. Sand, or more often powdered eggshell or marble dust, was chosen for flowing evenly regardless of temperature. Full-screen mode on this page removes everything but the glass, which is how most people use it for a quiet countdown.