Flip Clock

What flip clock does

A flip clock shows the time on split-flap panels, where each digit is a stack of hinged leaves and the top half of the old number falls forward to reveal the new one. This is that clock, full screen, in your browser. People run it on a spare monitor, an old tablet propped on a desk, or a television being used as a wall clock, because a large legible time readable from across a room is more useful than a small one you have to walk over to read.

How to use it

1. Choose 12 or 24 hour, and whether you want seconds.
2. Turn on dim mode if it will be running overnight or in a dark room.
3. Click the clock, or press F, to fill the display.
4. Leave it. It runs from your device clock and needs no connection once loaded.

About flip clock

Where split-flap displays come from

The split-flap mechanism was developed for public information boards and became the standard for railway stations and airports through the second half of the twentieth century, where the clatter of a whole board updating at once was part of the experience of travelling. The same mechanism went into consumer clock radios, which is where most people actually encountered it, sitting on a bedside table through the 1970s and 1980s. Almost all of the boards have now been replaced by LCD panels, which is precisely why the sound and the motion carry the nostalgia they do.

Why the animation matters

A digit that cross-fades reads as a web page. The split-flap motion is specific: the top half of the outgoing number rotates forward and down while the bottom half of the incoming number swings up behind it, so for a moment you see the top of the new digit and the bottom of the old one at once. Reproducing that, rather than approximating it with a fade, is the difference between something that evokes the object and something that merely displays the time in a similar font.

Running it overnight, and what dim mode is for

A bright clock in a dark bedroom is genuinely disruptive, and light in the evening is the most effective thing at shifting the body clock. Dim mode lowers both brightness and contrast so the time stays readable while emitting far less light. There is a second reason to use it: a clock is close to the worst case for OLED burn-in, because the digits are static, bright, and in the same position for hours. Dimming reduces how hard the emitters are driven, which is what actually determines wear.

Using an old device as a dedicated clock

An old phone or tablet, plugged in with the screen timeout disabled, makes a good desk or bedside clock, and this page will hold the display awake while it is in fullscreen. Two things worth setting: turn the brightness well down, since a device intended for daylight use is far too bright for a dark room, and use dim mode. If the device is old enough that its battery is degraded, running it permanently on the charger is easier on it than repeated cycling.