TimerPlanClocks and screen
Two kinds of tool that share one idea — a screen filling up with one thing. A clock big enough to read across a room, or a flat colour used as a lamp.
Black screen
Shows every smear a bright screen hides.
Full screen clock
Digital and analogue, big enough to read across a room.
Green screen
Chroma green at #00B140, and blue when green is in shot.
Time zone converter
This time here, that time there — and which day.
White screen
A monitor used as a lamp — warm, daylight or cool.
World clock
Local time, date and whether they're awake.
The world clock keeps a list of cities with the current time in each, the difference from your own zone, and a day-or-night mark so you can see at a glance who you would be waking. The time zone converter answers the single question underneath it: this time, here — what time is that there, and is it still the same day?
Both work from named zones and today’s rules, which is the whole point. The gap between London and New York is five hours for most of the year and four for three weeks in spring, because the two countries change their clocks on different dates. A stored number cannot know that.
The full screen clock is a clock big enough to be the only thing on a monitor: digital with seconds, a sweeping analogue face beside it, and a switch between 12 and 24 hour. It is the tool for a spare screen, a kitchen tablet or a stage monitor.
The colour panels use the screen as a light rather than as a display. The white screen is the one people reach for most — a lamp for a video call, a lightbox for tracing, a flat field for checking a screen after cleaning. The black screen is its opposite and shows exactly what the white one hides: dust, smears and reflections. The green screen is a keying backdrop at the standard value, with blue alongside for when green is in the shot.
If you need the screen to show a number rather than a colour, the classroom timer and the online timer both run full screen, and the world meeting planner turns a list of zones into the hours everybody is actually awake.
Frequently asked questions
Why not just look up a time zone's offset?
Because it changes. Most of Europe and North America shift by an hour twice a year, on different dates from each other, and several countries have changed the rule outright in the last few years. A table written in January is wrong for half the summer. These pages ask your browser’s own time-zone database for the offset at the moment in question, which is the same database your operating system updates.
Is a country the same as a time zone?
Not usually. France has twelve zones counting its overseas territories, the United States has six before you get to unofficial ones, and Australia splits into three that include a half-hour offset. That is why the tools here work in IANA zone names — Europe/Paris, America/Denver — which name a place whose clocks have always agreed with each other, rather than a flag.
Can a web page change my screen brightness?
No. Nothing in a browser can reach the backlight. Dimming on the colour panels lays a semi-transparent black layer over the colour, which genuinely reduces the light coming out of the screen but does not reduce the power it draws. Any page claiming to control brightness itself is either describing this same trick or describing something it cannot do.
What is chroma green, exactly?
A saturated green chosen because almost nothing in an ordinary scene shares it, so software can key it out cleanly. The panel uses #00B140, the value used for keying backdrops. Blue at #0047BB is the alternative for when the subject is wearing or holding green — the same reason film crews keep both.
Why would anyone want a plain white screen?
As a light. A monitor at full white is a soft, broad light source, which is why it is the fastest fix for a video call in a dark room, and why tracing paper against a bright screen works as a lightbox. A plain black screen has its own use: dust, smears and reflections are invisible against a bright picture and obvious against black, which is why it is the last step of cleaning a screen rather than the first.
How this works
Sources: