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America/Chicago time zone

7:08AMCST

CSTUTC−6−1 h vs New York (you)

About America/Chicago

America/Chicago is the IANA time zone for Central (most areas) in United States. It currently keeps Central Standard Time (CST, UTC−6) in winter and Central Daylight Time (CDT, UTC−5) in summer.

Its principal location is Chicago at 41.85° N, 87.65° W.

Abbreviations in use: CST, CDT. Offset page: UTC−6.

Rule for future years (POSIX TZ string)

CST6CDT,M3.2.0,M11.1.0

The standard time is called CST and is UTC−6. POSIX writes the offset with the opposite sign (west of Greenwich is positive), which is why the string says "6". Daylight saving time is called CDT and is UTC−5. It starts on the second Sunday of March at 02:00 and ends on the first Sunday of November at 02:00, local time. Software that has no full tzdata copy, such as many embedded devices, can use this string directly as the TZ environment variable.

Upcoming transitions

Computed from tzdata 2026f; local times are read on the clock just before each change.

History of America/Chicago since 1970

The record starts with local mean time (UTC−5:51), which ended on November 18, 1883. The first daylight saving time in the record is in 1918.

YearsClocksAbbreviations
1970–1973UTC−6 in winter, UTC−5 in summerCST, CDT
1974mostly UTC−5; also UTC−6 for part of the yearCST, CDT
1975 onwardUTC−6 in winter, UTC−5 in summerCST, CDT

Before 1970

99 offset changes before 1970 in the record; the first 12 and the last 12:

tzdata commits to accuracy from 1970 for every zone (zone1970.tab); earlier entries are historical research and may be incomplete.

Aliases and zones with the same clock

These older or country-specific IDs are links to America/Chicago in tzdata. Their pages redirect here: US/Central.

Other zones that keep exactly the same time under the current rules (but have a different history): America/Indiana/Knox, America/Indiana/Tell_City, America/Matamoros, America/Menominee, America/North_Dakota/Beulah, America/North_Dakota/Center, America/North_Dakota/New_Salem, America/Ojinaga, America/Rankin_Inlet, America/Resolute.

Places on America/Chicago

Convert Chicago time

Tip: Alt+↑/↓ steps the time by 15 minutes (Shift: one hour). The link keeps the date, time and direction.

Using America/Chicago in code

Every major platform reads the same IANA ID. Store instants in UTC and convert with the ID at display time; never store a fixed offset for a place that has daylight saving time.

// JavaScript
new Date().toLocaleString('en-US', { timeZone: 'America/Chicago' })

# Python 3.9+
from zoneinfo import ZoneInfo
from datetime import datetime
datetime.now(ZoneInfo('America/Chicago'))

// Java
java.time.ZonedDateTime.now(java.time.ZoneId.of("America/Chicago"))

// Go
loc, _ := time.LoadLocation("America/Chicago")
time.Now().In(loc)

-- PostgreSQL
SELECT now() AT TIME ZONE 'America/Chicago';

# Shell
TZ='America/Chicago' date

Platforms ship their own copy of tzdata and update it on their own schedule. After a rule change, outputs can differ until the platform updates; this page uses tzdata 2026f.

Questions

What is the UTC offset of America/Chicago?
UTC−6 in winter and UTC−5 in summer (daylight saving time from the second Sunday of March at 2:00 AM to the first Sunday of November at 2:00 AM).
Does America/Chicago observe daylight saving time?
Yes: clocks move one hour forward on the second Sunday of March at 2:00 AM and back on the first Sunday of November at 2:00 AM.
Is US/Central the same as America/Chicago?
Yes. US/Central is a link (alias) to America/Chicago in tzdata and gives the same time since 1970. It remains a valid ID.
Which countries use America/Chicago?
United States, according to zone1970.tab in tzdata.

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