What time is it there — and when does your meeting land for everyone?
DST-aware via your browser anchored to —
Live · every 30s
PresetsZones
Add or remove cities 215 in the catalogue · search, sort, click›
Meeting planner
The day across your cities
green = 8am–8pm · the shaded band is the best window · drag the marker to retime
Clock changes
Every clock change this year, city by city
summer timewinter (standard) timeno clock changesusual gapseasonal gapgap briefly different⇡ forward · ⇣ back · | chosen date
The gap as a number, through the year
Summer and winter zones
Each city's two clocks, how far apart they are, and exactly when it switches between them. Countries set their own dates, so neighbours rarely switch on the same day — and the southern hemisphere does it the other way round.
Right now
Who is awake, and where the sun is
workingearlyeveningasleep
The dark half is computed from the sun's actual position for the date and time set above —
solar declination, the equation of time, and the terminator where the sun sits exactly on the
horizon. Move the time and the shadow moves with it. The coastlines are a five-degree
schematic for orientation and nothing more; the daylight is real.
Markets
Which exchanges are trading right now
Continuous session only — pre- and post-market are excluded, and Tokyo, Shanghai and
Hong Kong take a real lunch break that is shown separately. Weekends are the exchange's own,
not yours. Public holidays are not modelled, and session times change occasionally, so
check the exchange for anything that depends on it. Press Stock markets above to load
these cities as a comparison set.
Every pair
Which two cities are the problem
The whole list
Every IANA time zone, by region
Read from your browser's own copy of the IANA database, so it is complete and as current as
your device — nothing is shipped with the page that could go stale. Click any zone to
make it the anchor.
How it works
Why the same clock reads differently
UTC offset
How many hours a place is ahead of or behind UTC. London is UTC+0 in winter; New York is UTC−5. The offset, not the country, determines the local clock.
Daylight saving
Many regions shift in summer, changing their offset for part of the year. The tool reads your browser’s tz database, so it uses the rules for the date you pick, not just today.
Comfortable hours
The green band marks roughly 8am–8pm local, when someone is plausibly awake and working, so you can spot a slot that is not the middle of someone’s night.
Half-hour zones
Not every zone is a whole number of hours: India +5:30, Nepal +5:45, parts of Australia +9:30. Handled correctly because it uses real zone data.
London – New York, most of the year5 hours
… for 2–3 weeks in spring and one in autumn4 hours
Worked example. A 9am meeting in London in January (GMT, UTC+0) lands at 1am in Los Angeles (PST, UTC−8), an 8-hour gap. The same 9am London meeting in July is 1am Pacific Daylight Time, because both zones have shifted, but not always by the same amount or on the same date. The US moves on the second Sunday of March and the first Sunday of November; the UK, like the EU, on the last Sundays of March and October, so for a few weeks only one of them has changed and the usual five-hour gap to New York is four. The Clock changes section finds these spells for any cities you pick.
Field notes
How time zones work
The offset, not the country
London is UTC+0 in winter and UTC+1 in summer; New York UTC−5 and −4. Pick a date and two places and the conversion accounts for the rules in force on that specific date, which is why scheduling something six months out can trip people up.
Why some countries do not observe daylight saving
It mainly benefits places with a big seasonal swing in daylight hours, the mid-to-high latitudes. Countries near the equator see little change and many skip it, while others have abandoned it for practical or political reasons.
+5:45
Half-hour and 45-minute zones
Time zones are nominally 15° of longitude wide, but borders follow countries, not meridians. India (+5:30), Nepal (+5:45), Iran and parts of Australia (+9:30, +8:45) sit a half or three-quarter hour off the nearest whole hour, usually to sit in the middle of a wide country’s longitude span.
How current are the rules?
They come from your browser’s built-in IANA tz database, updated alongside your browser or operating system, so the rules are as current as your device: a long-unpatched browser could carry outdated transition dates.
Governments change the rules at short notice
Daylight-saving dates have been moved, or DST abolished, with only a few months’ notice. For anything truly time-critical, especially in the near future, double-check against an official government or airline source.
Questions
What people ask
Why are London and New York sometimes four hours apart, not five?
Because they change their clocks on different days. The US moves on the second Sunday of March and
the first Sunday of November; the UK, like the EU, on the last Sundays of March and October. For two or
three weeks in spring and one in autumn only one of them has changed, and the usual five-hour gap is four.
The Clock changes section above finds these spells for any cities you pick, and shades them red.
Why do some countries not observe daylight saving?
Daylight saving mainly benefits places with a big seasonal swing in daylight hours — mid-to-high
latitudes. Countries near the equator see little seasonal daylight change, so many skip it entirely, while
others have abandoned it for practical or political reasons.
Why does the offset sometimes include a half hour?
Time zones are nominally 15° of longitude (1 hour) wide, but borders follow countries, not meridians. A
handful of places — India, Iran, parts of Australia — set their offset a half or even three-quarter hour
off the nearest whole hour, usually to sit in the middle of a wide country's longitude span.
How current are the daylight-saving rules used here?
They come from your browser's built-in time-zone database (the IANA tz database), which is updated
alongside your browser or operating system. That means the rules are as current as your device — a
long-unpatched browser could carry outdated transition dates.
Can a country change its time zone with little warning?
Yes — governments have moved daylight-saving start/end dates, or abolished DST altogether, sometimes with
only a few months' notice. For anything truly time-critical, especially in the near future, it's worth
double-checking against an official government or airline source.
Results are for reference only. Time-zone rules and daylight-saving dates change; double-check anything time-critical against an authoritative source.
Version history · 14 releases
v0.982026-07-28Welch two-sample t-test in Statistics. One tool, not three — two candidates already had the feature
v1.942026-08-09Time zones: 50 cities to 172, every IANA zone grouped by region, and a world map whose night side is computed from the sun's real position
v1.952026-08-09Time zones: searchable sortable city picker, zone and market presets, land tinted by UTC offset, and the remove button that sat on top of every clock
v1.962026-08-09World map colour ramp rebuilt in OKLCH and chosen by measurement — three offsets used to share one colour
v1.972026-08-0922 more cities in the time-zone catalogue, and Frankfurt stops being bolted on at runtime
v1.982026-08-09The sort control now orders the chosen cities too, not just the picker — four lists were each building their own order
v3.252026-08-16Profiling the rest of the tool pages found one outlier: the time-zone converter rebuilt 4,000 off-screen nodes on load and on every input
v5.252026-09-13The time-zone converter audited for speed-to-answer: opens on the reader's own zone, a quick bar, ticking analogue faces tinted by daylight, the best meeting window shaded on the strip, the picker folded away, one business window everywhere and a pair grid that printed undefined
v5.292026-09-13Four reported bugs: the atlas re-requested a blocked detail file on every pan for ever and blurred its backdrop on every mouse move; the country table is a twenty-row scroll box with the header pinned; the world clocks are an aligned list in time order with a button back to the cards; the time-zone toolbar no longer overlaps the labels above it
v5.302026-09-13The homepage demos: every one of them now holds 60 fps (they were dropping to 15), fills its panel instead of leaving a quarter of it empty, and carries no text over the picture. One molecule and one element per visit, the atom in 3D like its own tool, a guitar neck that matches the chord finder with the string stopped at the finger, a steak that turns every three minutes, and an orbit you can actually read
v6.112026-09-29Time zones: every clock change found for each city, the year shown as a gap to the anchor or as each city's own offset, and summer and winter zones side by side
v6.122026-09-29Time zones: clock-change crossovers readable at any width - labels on stalks, a plot of the hour offset, and a close-up of every brief spell
v6.152026-09-29Time zones: the offset chart shares its time axis with the clock-change lanes above it
v6.162026-09-29Time zones: a third view - every city's clock through the year at the anchor's chosen time
Releases in which this page changed, newest last. Derived from the archived copy of every release, not from notes written afterwards — so it reflects what actually shipped. Site-wide passes are left out; they are in the full changelog.
Rules of thumb are approximations, offered to get you to the right order of magnitude fast. Check anything load-bearing against its source or the exact tool. Privacy·Terms