Convert UTC to CST Coordinated Universal Time ↔ Central Standard Time Free Online Secure
Type a time in UTC and read it in CST straight away. The offset is −6 h, the arithmetic wraps at midnight, and the answer says which day it lands on.
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Through the day — Convert UTC to CST (Coordinated Universal Time ↔ Central Standard Time)
| UTC | CST |
|---|---|
| 00:00 | 18:00 |
| 03:00 | 21:00 |
| 06:00 | 00:00 |
| 09:00 | 03:00 |
| 12:00 | 06:00 |
| 15:00 | 09:00 |
| 18:00 | 12:00 |
| 21:00 | 15:00 |
Where these units come from
Until the middle of the nineteenth century every town kept its own noon, set by the sun overhead, and nobody minded that the next town was four minutes behind. Railways ended that: a timetable cannot be written for a hundred local noons. Britain put its railways on Greenwich time in 1847, and in 1884 the International Meridian Conference in Washington chose Greenwich as the prime meridian and sketched the twenty-four-hour scheme we still use. Greenwich Mean Time was the world's reference until 1972, when Coordinated Universal Time replaced it: UTC is kept by atomic clocks and tied back to the turning Earth by leap seconds. The abbreviations on this page name standard time — the winter setting — which is why each one is a fixed number of hours rather than something that drifts through the year.
Where you meet them
A time zone becomes real the moment two people in different places have to agree on one moment: a call between offices, a flight that lands before it took off, a market that opens while you are asleep, a deadline written in somebody else's afternoon. Server logs, train and flight schedules and anything stamped with a time are kept in UTC precisely so that the question can always be settled, no matter whose clock was on the wall.
Questions people ask
What about summer time?
The offsets here are standard-time offsets, the ones a zone keeps in winter. Where summer time is observed, the same places move one hour further on for part of the year and take a different name: Central European Time becomes Central European Summer Time, Eastern Standard Time becomes Eastern Daylight Time. The switching dates are not the same in every country, and the two hemispheres change in opposite months, so for a date inside a summer-time period add an hour to whichever side observes it.
Why isn't every difference a whole number of hours?
Because offsets are decided by governments, not by geometry. India is half an hour off the hour, at UTC+05:30; Nepal is three quarters, at UTC+05:45; the Chatham Islands are at UTC+12:45. Any of these can be changed by law, and several countries have moved their offset within living memory.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
UTC readings for the heart of North America
Storm warnings, pipeline notices, flight plans and server logs speak UTC. The people who act on them in Chicago, Dallas, Houston, Minneapolis, Winnipeg or Mexico City read the Central wall clock. To move from one to the other you must convert UTC to CST, and the sum is a subtraction of six hours: 18:40 UTC is 12:40 CST, 23:00 UTC is 17:00 CST, and 03:00 UTC is 21:00 CST on the previous evening. Every UTC reading from 00:00 to 05:59 belongs to the previous calendar date in the Central zone.
This page sets out the rule, supplies two tables, introduces both zones, and explains what happens when North America changes its clocks and UTC does not. It also looks at a series of cases: natural-gas trading days, severe-weather outlooks, spaceflight operations, airline hubs and the Canadian prairies. The arithmetic happens in your browser, and nothing is sent to a server.
How to convert UTC to CST
Take six hours away
Central Standard Time is UTC−6. Subtract six from the UTC hour each time you convert UTC to CST. If the answer is negative, add 24 and step back one date. For instance, 04:20 UTC gives −1:40, which is 22:20 CST on the previous day.
Eight pairs of readings
00:30 UTC is 18:30 CST the day before. 06:15 UTC is 00:15 CST. 09:00 UTC is 03:00 CST. 12:00 UTC is 06:00 CST. 15:45 UTC is 09:45 CST. 18:00 UTC is 12:00 CST. 21:30 UTC is 15:30 CST. 23:45 UTC is 17:45 CST. Only the first falls on the earlier date.
Noon as an anchor
Central noon is exactly 18:00 UTC. From there, other hours follow by counting: 09:00 CST is three hours earlier, so 15:00 UTC; 17:00 CST is five hours later, so 23:00 UTC. Counting from an anchor is quicker than a full sum whenever you convert UTC to CST in your head.
UTC in forecasts and bulletins
The letter Z
Weather services, airlines and armed forces call UTC “Zulu time” and mark it with a Z. A bulletin timed 031200Z means the third day of the month at 12:00 UTC, which is 06:00 CST. The letter removes any doubt about whose clock is meant.
No daylight saving
UTC does not change with the seasons and belongs to no country. Pilots, forecasters and programmers prefer it because one figure is valid everywhere, and everyone who reads it can convert UTC to CST without asking which law applies.
Central Standard Time
Cities and countries
CST, UTC−6, is the winter time of Chicago, Dallas, Houston, San Antonio, Austin, Minneapolis, Kansas City, New Orleans, Memphis, Nashville, Winnipeg and Mexico City. Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and the Canadian province of Saskatchewan use UTC−6 all year. Mexico stopped changing its clocks in 2022.
The summer name
In the United States and Canada, between the second Sunday of March and the first Sunday of November, the Central zone uses CDT, UTC−5. In 2026 that means 8 March to 1 November. Mexico City stays on UTC−6, so in summer it is an hour behind Chicago.
Other CSTs
CST also stands for China Standard Time (UTC+8) and Cuba Standard Time (UTC−5). This converter always means the North American Central zone.
Six hours and the working day
Shared hours
A Chicago office open from 09:00 to 17:00 CST is open from 15:00 to 23:00 UTC. A European office open from 08:00 to 16:00 UTC overlaps with it only between 15:00 and 16:00 UTC, which is 09:00 to 10:00 CST. Joint calls therefore fall at the very start of the American morning.
Maintenance windows
A window from 03:00 to 05:00 UTC falls between 21:00 and 23:00 CST, in the evening. A window from 08:00 to 10:00 UTC falls between 02:00 and 04:00 CST, when traffic is at its lowest. Choose the UTC hours with the Central users in mind.
Daily cut-offs
A report that closes at 00:00 UTC covers, for Chicago, the period from 18:00 CST yesterday to 18:00 CST today. Evening sales therefore appear in the next day’s UTC report.
When North America changes clocks and UTC does not
The calendar
UTC never moves, but the Central zone does so twice a year. In 2026 it moves forward on 8 March and back on 1 November. Between those dates Chicago is on CDT, UTC−5, so 18:00 UTC is 13:00 CDT, not 12:00 CST.
The effect on schedules
A job that runs at 14:00 UTC all year starts at 08:00 CST in winter and 09:00 CDT in summer. A team that wants it to start at 08:00 local time all year must move the UTC hour in March and November.
What the calculator does
The form above subtracts six hours, the standard figure. For a date between 8 March and 1 November, subtract five and label the result CDT. For Mexico City, subtract six all year.
The natural-gas trading day
A day that starts at nine
In North American gas markets the “gas day” begins at 9:00 a.m. Central Clock Time. In UTC, that is 15:00 in winter. In summer, when the clock is CDT, the gas day still starts at 9:00 a.m. local, which is 14:00 UTC. Traders and schedulers in Europe who deal with American pipelines must remember the shift.
Nominations
Deadlines for nominating volumes are stated in Central time. A cut-off at 1:00 p.m. CST is at 19:00 UTC. A colleague in London who sends the request at 18:30 GMT is inside the window by half an hour. A short convert UTC to CST before each cut-off prevents disputes.
Severe-weather outlooks
Forecasts in Zulu
Outlooks for thunderstorms and tornadoes in the Central United States are issued several times a day and carry valid times in UTC. A product valid “until 0300Z” expires at 21:00 CST on the previous evening, or at 22:00 CDT in the storm season. The label of the local clock matters.
For people abroad
Researchers and insurers in Europe who track severe weather read the same bulletins. If a hail event is reported at 21:30Z, it took place at 15:30 CST, and the claims office in London sees it as an evening event.
Spaceflight operations in Houston
The crew’s clock
The crew of the International Space Station lives on UTC, which space agencies call GMT. Mission control in Houston works on Central time. An activity planned for 14:00 UTC is at 08:00 CST for the flight controllers. The crew’s sleep period, from 21:30 to 06:00 UTC, is 15:30 to 00:00 CST.
Spacewalks
A spacewalk that begins at 12:30 UTC begins at 06:30 CST and lasts about seven hours. If you follow it from Europe, you convert UTC to CST to find the start and then again for the end.
Airline hubs in Chicago and Dallas
Connections measured in UTC
Large airlines run their operations control centres on UTC, even though the hubs they serve keep local time. A departure scheduled for 14:15 CST is 20:15 UTC. A crew whose duty period is limited to 14 hours must be tracked in UTC to avoid mistakes at the clock change.
Passengers’ view
Boarding passes show local times. A flight from Chicago at 18:00 CST that takes seven hours to London lands at 07:00 UTC. The ticket shows 18:00 and 07:00, which makes the trip look like a thirteen-hour journey.
Mexico City: a fixed clock
Why it differs from Chicago in summer
Mexico gave up daylight saving time in 2022, so Mexico City stays on UTC−6 all year. In winter its clock matches Chicago’s. In summer it is an hour behind. The gap to UTC is six hours in every month.
An example
15:00 UTC is 09:00 in Mexico City in both January and July. In Chicago the same moment is 09:00 CST in January and 10:00 CDT in July. The sum you do when you convert UTC to CST is constant for Mexico and variable for the United States.
Barges on the Mississippi
Schedules along the river
Lock operators, tow companies and grain terminals along the river post times in local time. A lock passage scheduled for 6:00 a.m. CST takes place at 12:00 UTC. A grain buyer in Rotterdam who tracks the cargo has to move each event on to the UTC scale before comparing it with the ship’s arrival.
Water levels
Gauge readings are stamped in local time. A reading taken at 7:00 a.m. CST was taken at 13:00 UTC. A flood forecast that says “crest expected 18Z Tuesday” means noon on the same day in Memphis.
Friday-night football in Texas
The kick-off
High-school football games in Texas begin at 7:00 p.m. local time on Friday. In autumn the clock is CDT, so the kick-off is at 00:00 UTC on Saturday. In late November, after the clocks change, 7:00 p.m. CST is 01:00 UTC.
Streaming from abroad
Families abroad who watch the stream see the game in the small hours of Saturday. Anyone setting an alarm should check which label the schedule uses before they convert UTC to CST.
Every hour in one table
UTC to CST
00:00 UTC becomes 18:00 CST (previous day). 01:00 UTC becomes 19:00 CST (previous day). 02:00 UTC becomes 20:00 CST (previous day). 03:00 UTC becomes 21:00 CST (previous day). 04:00 UTC becomes 22:00 CST (previous day). 05:00 UTC becomes 23:00 CST (previous day). 06:00 UTC becomes 00:00 CST. 07:00 UTC becomes 01:00 CST. 08:00 UTC becomes 02:00 CST. 09:00 UTC becomes 03:00 CST. 10:00 UTC becomes 04:00 CST. 11:00 UTC becomes 05:00 CST. 12:00 UTC becomes 06:00 CST. 13:00 UTC becomes 07:00 CST. 14:00 UTC becomes 08:00 CST. 15:00 UTC becomes 09:00 CST. 16:00 UTC becomes 10:00 CST. 17:00 UTC becomes 11:00 CST. 18:00 UTC becomes 12:00 CST. 19:00 UTC becomes 13:00 CST. 20:00 UTC becomes 14:00 CST. 21:00 UTC becomes 15:00 CST. 22:00 UTC becomes 16:00 CST. 23:00 UTC becomes 17:00 CST.
How to read it
Each entry pairs a UTC hour with the matching Central hour and says when the date moves. The rows follow the six-hour subtraction that applies when you convert UTC to CST.
Half-hour marks
UTC to CST at :30
00:30 UTC becomes 18:30 CST (previous day). 01:30 UTC becomes 19:30 CST (previous day). 02:30 UTC becomes 20:30 CST (previous day). 03:30 UTC becomes 21:30 CST (previous day). 04:30 UTC becomes 22:30 CST (previous day). 05:30 UTC becomes 23:30 CST (previous day). 06:30 UTC becomes 00:30 CST. 07:30 UTC becomes 01:30 CST. 08:30 UTC becomes 02:30 CST. 09:30 UTC becomes 03:30 CST. 10:30 UTC becomes 04:30 CST. 11:30 UTC becomes 05:30 CST. 12:30 UTC becomes 06:30 CST. 13:30 UTC becomes 07:30 CST. 14:30 UTC becomes 08:30 CST. 15:30 UTC becomes 09:30 CST. 16:30 UTC becomes 10:30 CST. 17:30 UTC becomes 11:30 CST. 18:30 UTC becomes 12:30 CST. 19:30 UTC becomes 13:30 CST. 20:30 UTC becomes 14:30 CST. 21:30 UTC becomes 15:30 CST. 22:30 UTC becomes 16:30 CST. 23:30 UTC becomes 17:30 CST.
Why it helps
Many bulletins and scheduled jobs sit at half past the hour, for example 14:30 UTC. The table gives the Central time at a glance.
Ten readings with minutes
Examples
01:05 UTC becomes 19:05 CST (previous day). 03:20 UTC becomes 21:20 CST (previous day). 05:50 UTC becomes 23:50 CST (previous day). 07:35 UTC becomes 01:35 CST. 10:10 UTC becomes 04:10 CST. 13:25 UTC becomes 07:25 CST. 16:40 UTC becomes 10:40 CST. 19:55 UTC becomes 13:55 CST. 22:15 UTC becomes 16:15 CST. 23:05 UTC becomes 17:05 CST.
The minutes do not move
Because six hours is a whole number of hours, the minutes in the result match the input.
What part of the day is it in the Central zone?
Central hours for each UTC hour
06:00 UTC becomes 00:00 CST (night). 08:00 UTC becomes 02:00 CST (night). 10:00 UTC becomes 04:00 CST (night). 12:00 UTC becomes 06:00 CST (early morning). 14:00 UTC becomes 08:00 CST (morning). 16:00 UTC becomes 10:00 CST (morning). 18:00 UTC becomes 12:00 CST (around midday). 20:00 UTC becomes 14:00 CST (afternoon). 22:00 UTC becomes 16:00 CST (afternoon).
Using the list
The words in brackets describe the part of the day in the Central zone. They help you avoid planning a call or a maintenance task at the wrong hour.
The American zones from UTC
How far each zone sits
Eastern time is five hours from UTC, Central six, Mountain seven and Pacific eight; Alaska is nine and Hawaii ten. In summer, the zones that observe daylight saving move one hour closer to UTC.
The same instant in five cities
While UTC shows 18:00, Chicago shows 12:00, New York 13:00, Denver 11:00 and Los Angeles 10:00. An invitation that lists them all spares readers a separate convert UTC to CST.
Dated examples
January
On Thursday 15 January, 17:00 UTC is 11:00 CST. No daylight saving is in force, so subtract six hours.
Mid-March
On Thursday 19 March, 17:00 UTC is 12:00 CDT. The United States moved on 8 March, so subtract five hours.
August
On Thursday 13 August, 17:00 UTC is 12:00 CDT in Chicago and 11:00 in Mexico City.
Early November
On Thursday 5 November, 17:00 UTC is 11:00 CST. The Central zone returned to standard time on 1 November.
Checklist: how to convert UTC to CST
Before
Read the label
CST, CDT or CT? If the source says CT and the date is between 8 March and 1 November, it is CDT, UTC−5.
Check the country
CST may also mean China or Cuba. Here it is North American Central.
After
Subtract six
If the UTC hour is below 06:00, add 24 first.
Check the date
UTC readings from 00:00 to 05:59 belong to the previous date in Chicago.
Winnipeg, Regina and the prairie provinces
One province that does not change
Manitoba, whose capital is Winnipeg, follows the Central zone with the usual summer shift. Saskatchewan, with Regina and Saskatoon, stays on UTC−6 all year. In July, therefore, Regina is one hour behind Winnipeg, and 17:00 UTC is 11:00 in Regina and 12:00 in Winnipeg.
Why it matters for schedules
A Canadian organisation that says “Central time” without naming a city invites trouble. For a webinar in July, ask whether the host means Winnipeg or Regina. In winter the two clocks agree, and 17:00 UTC is 11:00 in both.
Mistakes when you convert UTC to CST
Adding
Chicago is behind UTC. If your answer is later than the UTC time, you added.
Using five hours in winter
Five hours is for CDT or for the Eastern zone. In winter the Central zone needs six.
Losing the previous date
02:00 UTC is 20:00 CST the previous day. Keeping the date creates a 24-hour error.
Assuming Mexico shifts
Mexico City does not move to summer time, so it stays six hours behind UTC all year.
Frequently asked questions
How far apart are UTC and CST?
Six hours, with CST behind.
How do I convert UTC to CST?
Subtract six hours, adding 24 and stepping back a date if the result is negative.
What is 18:00 UTC in CST?
12:00 CST.
Why do I sometimes subtract five hours?
Because the United States and Canada use CDT, UTC−5, between the second Sunday in March and the first Sunday in November.
Is my input uploaded?
No. It stays in your browser.
More time zone converters
Related pages: Convert UTC to EET, Convert UTC to PST, Convert EST to CST, Convert CET to CST, Convert CST to WET, Convert GMT to UTC, Convert PST to GMT, Convert CET to PST, Convert CET to EST. For the reverse direction, open Convert CST to UTC.
In brief, to convert UTC to CST you subtract six hours, mind the previous date and switch to five hours during daylight saving time. The calculation runs on your own device, with no sign-up and no upload.