What time is it,
and what time is it there?

CENTRAL
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UNIVERSAL
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TIME SHIFT live
-24h-12hnow+12h+24h

The slider moves in half hour steps, because a fair number of the world's zones do too. Everything on this page moves with it: all 24 standard zones above, the city table, the meeting planner, and both maps. The daylight on the world map is computed from the sun's actual position at the selected instant rather than faked from the hour.

world

The world, on Equal Earth

subsolar point - night day at - UTC declination - equation of time -
Equal Earth (Šavrič, Patterson and Jenny, 2018) is an equal-area pseudocylindrical projection, so every country covers the share of the map its actual area deserves. Greenland is the size of Greenland. The faint vertical bands are nominal 15 degree solar hours. Real civil zones follow political borders and are considerably messier, which is what the map further down shows.
planner

When can we all be awake at once?

Pick the places you actually deal with. Each row is one location's local hour across a full Central day, colored by whether a normal person there would be at work, awake, or asleep. Click any column to move the whole page to that hour.

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cities

Every offset, somewhere real

Every UTC offset kept by a populated place, including the half and three quarter hour ones, each anchored to somewhere that actually keeps it. Offsets and abbreviations come from your browser's own IANA timezone database, so daylight saving is resolved for the date you have dragged to rather than for today.

CityCountryTimeDate ZoneUTCVs. Central
united states

Six zones, and the borders are not straight

Zone areas are built from the actual boundaries, county by county, so the splits are real: the Florida panhandle, the western tip of Michigan's Upper Peninsula, the Indiana and Kentucky and Tennessee lines, El Paso, and the jogs through the Dakotas, Nebraska, Kansas, Idaho and Oregon. State outlines are drawn on top in gray for reference. Alaska and Hawaii sit in the conventional Albers USA inset positions rather than their true geographic ones.
Arizona is hatched because it does not observe daylight saving, with one wrinkle: the Navajo Nation within Arizona does observe it, and the Hopi Reservation inside the Navajo Nation does not. That is finer than county resolution, so this map does not attempt it. Neither does time.gov.
local

Here, specifically

Sun times computed for Batavia, Illinois at 41.85 N, 88.31 W from the solar position at the selected instant. Rise and set use the standard -0.833 degree altitude, which allows for refraction and the sun's radius.

% Local reference, Batavia, Illinois
timezone-
utc-offset-
dst-
sunrise-
solar-noon-
sunset-
day-length-
grid-squareEN51uu

Machine time

% The same instant, in the formats that matter to computers
iso-8601-utc-
iso-8601-local-
rfc-2822-
unix-epoch-
julian-day-
modified-jd-
day-of-year-
iso-week-
gps-week-
swatch-beat-
remarks

Why UTC, and why this page exists

Every amateur radio log entry, every server timestamp, and every incident timeline I have ever had to reconcile is in UTC, because the alternative is arguing about whose Tuesday it was. Local time is for humans, universal time is for records. This page keeps both in front of me.

  • UTC is not GMT, though they agree to within a second. GMT is a time zone, still legally used in the UK in winter. UTC is a time standard, held to atomic time by the BIPM and nudged with leap seconds to stay within 0.9 seconds of the earth's actual rotation.
  • Zulu is UTC, from the NATO phonetic letter for the zero offset zone. Aviation, military and marine traffic all use it, which is why a log entry reads 1430Z.
  • The offsets are not all whole hours. India is UTC+5:30, Nepal is UTC+5:45, Newfoundland is UTC-3:30, and the Chatham Islands are UTC+12:45. Any code that assumes whole hours is already broken, which is why the slider here moves in halves.
  • China runs on one zone across a span that would naturally be five, so the sun comes up in Kashgar around ten in the morning by the clock. The world map shows why.
  • Nothing here is stored. No cookies, no local storage, no server call, no network request of any kind after the page loads. Everything is computed in your browser from your own system clock and your browser's timezone database.
Boundary data: coastlines from Natural Earth at 1:110m, US county geometry from the Census via us-atlas, and county to zone assignment derived from timezone boundary data. All of it simplified, packed, and embedded here so the page needs nothing at runtime.
Sun times are accurate to roughly a minute, which is fine for planning a contact and not fine for a grazing occultation. For real ephemeris work, the planetarium does it properly. For the official answer, time.gov is the one that counts.