About World Time Lab

World Time Lab is a live world clock built around one idea: you should be able to see where it is day and night right now, and then get the exact numbers behind that picture without signing up for anything.

Last reviewed July 21, 2026Site version v2026.7.5

What World Time Lab is

World Time Lab is a free, static website. Every page is pre-rendered and served as plain files. There is no account, no login, and no newsletter. The interactive parts run entirely in your browser: the globe is drawn on a canvas, the clocks read your browser's own time zone database, and the sun and moon numbers come from published astronomical formulas evaluated on your device.

Nothing here asks for your location on its own. One feature can ask, and only when you press its button: Use my locationin the eclipse tool, which saves you typing coordinates to find out whether an eclipse reaches you. What your browser returns is used in the page and kept in the page's own storage. It is not sent anywhere, because there is no server here to send it to, and it is never written into the address bar. The privacy policy spells that out, along with every storage key the site writes.

The centerpiece is the day and night globe on the home page. Drag it, search a place, scrub time forward and back, and the terminator moves with you. Around that sit the reference pages people actually search for: local time by country and by city, sunrise and sunset, moon phases, eclipses, equinoxes and solstices, date calculators, calendars, and a set of small timing tools.

What it computes

Each of these is calculated from an input you control, not looked up from a stored answer:

Local time and UTC offset for any time zone, including the daylight saving state that applies on the date you are asking about.
The day and night terminator, as a per-pixel field of solar altitude rather than a drawn line, which is why twilight fades instead of stopping abruptly.
Sunrise, sunset, day length, twilight bands and golden hour for a latitude, longitude and date, with polar day and polar night stated explicitly instead of failing quietly.
Moon phase and the instants of new, first quarter, full and last quarter.
Equinox and solstice instants, found by solving for the moment the sun's declination crosses the relevant value.
Date arithmetic: days between dates, adding and subtracting periods, week numbers, weekday of a date, and countdowns.
Great-circle distance between cities, and an educational planet simulator in the Planet Lab.

Eclipse pages are different: they present a published catalog rather than a live computation, and they say so. The methodology page separates the computed results from the cataloged ones, source by source.

What it does not do

It is not a weather service.The Seasons view colors the world by climate classification and the calendar, not by today's forecast. Nothing on the site reports current conditions.
It is not a navigational or aviation almanac. Times are given to the minute and assume a flat sea-level horizon, so a mountain, a building, or your altitude will move real sunrise by more than the arithmetic error.
It does not predict political decisions. When a country changes its clocks, World Time Lab follows the time zone database in your browser, which follows the official announcement. It does not guess at rule changes ahead of that.
It does not publish observance dates that depend on a local sighting or proclamation as if they were fixed. Where a date is set by moon sighting or by a government announcement, the calendar pages either omit it or label the uncertainty.
It does not track you. There is no profile, no fingerprinting script, and no attempt to work out who you are. The one feature that can ask for your location asks only when you press it, keeps the answer on your device, and never puts it in a URL. See the privacy policy for exactly what does and does not leave your device.

Why it exists

Time zone questions are easy to answer badly. Most tools give a number with no way to check it, and many of them wrap that number in a page that loads more tracking than content. World Time Lab was built the other way around: show the geometry, show the arithmetic, name every dataset, and keep the page fast enough to open on a slow connection.

The globe is the reason the rest of the site exists. Once you can see the terminator move across a real map, a question like "is it tomorrow in Sydney yet" stops being a lookup and becomes something you can see the answer to.

Why the data can be trusted

Published algorithms, not house formulas.Solar position uses the standard NOAA equations; moon phases follow Jean Meeus's truncated series. Both are documented on the methodology page with their stated accuracy.
Time zone rules come from your own browser. World Time Lab ships no time zone data at all. It asks the IANA database built into your device, so daylight saving is as current as your browser is.
Every dataset is named, with its terms and its age recorded. Map shapes, zone boundaries, administrative regions, city coordinates, climate classes and holiday sets all come from identified public sources, each with its license and its age recorded.
Releases are gated by validators.Automated checks construct every time zone id, re-derive the simulator's physics against Earth, Mars, Venus and Mercury, and re-check the generated holiday tables before a build is considered shippable.
Mistakes get fixed in public. If something is wrong, the corrections page explains what to send and what happens next.

How it is maintained

The version in the header and footer uses calendar versioning: year, month, then the release number within that month. This build is v2026.7.5. The footer also records the date the build shipped. Together they answer a fair question that most sites dodge: is anyone still looking after this?

Data that has a source snapshot, such as city coordinates, administrative regions, climate classes and holiday tables, is regenerated from its upstream source rather than edited by hand, and the regeneration is recorded. Data that has no snapshot, such as time zone rules, is deliberately not stored here at all.

Who runs World Time Lab

World Time Lab is published by the operator of World Time Lab. World Time Lab is not affiliated with, sponsored by, or endorsed by any of the organizations whose public data it uses, and it speaks for none of them.

The operator of World Time Lab can be reached through the contact page. For a data problem, the error report guide gets to a fix faster.

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