Convert CST to UTC Central Standard Time ↔ Coordinated Universal Time Free Online Secure
Type a time in CST and read it in UTC 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 CST to UTC (Central Standard Time ↔ Coordinated Universal Time)
| CST | UTC |
|---|---|
| 00:00 | 06:00 |
| 03:00 | 09:00 |
| 06:00 | 12:00 |
| 09:00 | 15:00 |
| 12:00 | 18:00 |
| 15:00 | 21:00 |
| 18:00 | 00:00 |
| 21:00 | 03:00 |
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.
From the Central clock to the one the world compares
An energy statistic is released at 9:30 a.m. in Houston. A factory in northern Mexico changes shift at 2:00 p.m. A crop report is posted at 3:00 p.m. in Chicago. All three are stated in Central time, and a reader who keeps records, schedules or contracts in UTC must convert CST to UTC before comparing them with anything else. Add six hours: 9:30 a.m. CST is 15:30 UTC, 2:00 p.m. CST is 20:00 UTC, and 3:00 p.m. CST is 21:00 UTC. From 6:00 p.m. CST onward, the UTC date is already the next one.
This page sets out the rule, offers two lookup tables, describes both zones and explains why you add only five hours when the United States and Canada are on summer time. It also works through cases from energy and farm statistics to border factories and long-haul flights. The calculation runs in your browser, and nothing you type is sent to a server.
The sum behind a “convert CST to UTC” calculation
Add six hours
CST is UTC−6, so UTC runs six hours ahead. Write the Central time on a 24-hour clock and add six each time you convert CST to UTC. If the total reaches 24:00, subtract 24 and advance the date. 21:10 CST plus six is 27:10, which is 03:10 UTC on the next date.
Eight readings
00:30 CST is 06:30 UTC. 06:15 CST is 12:15 UTC. 09:00 CST is 15:00 UTC. 12:00 CST is 18:00 UTC. 15:45 CST is 21:45 UTC. 18:00 CST is 00:00 UTC the next day. 21:30 CST is 03:30 UTC the next day. 23:45 CST is 05:45 UTC the next day. The first four stay on the same date.
The 6 p.m. threshold
At 18:00 in Chicago it is midnight in UTC. Everything that happens in the Central evening after that moment has tomorrow’s UTC date. Remember the threshold and you will avoid the most frequent slip when you convert CST to UTC for cross-border paperwork.
Central time in American and Mexican sources
CST, CDT, CT
CST is the winter label, UTC−6. CDT is the summer label, UTC−5, in force between the second Sunday in March and the first Sunday in November. CT covers both. Many people write CST all year, so a source that says CST in July is more likely to mean CDT, if it comes from the United States or Canada.
Places with a fixed clock
Mexico stopped changing its clocks in 2022. Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and the Canadian province of Saskatchewan stay on UTC−6 all year. For them, CST is right in every month, and the sum you do when you convert CST to UTC is always six hours.
UTC as the destination
Why UTC is requested
Contracts, audit logs, payment systems and customer databases that span several countries rely on UTC because it belongs to no country’s calendar. An event stated in UTC can be compared with any other event without recalculation.
The standard notation
A time recorded as 2026-01-13T09:00:00-06:00 equals 2026-01-13T15:00:00Z. Moving from the first form to the second is precisely the addition described here, and date libraries do it silently every time a record is stored.
Six hours in daily operations
Who sees what
An incident that begins at 3:00 p.m. CST is recorded in system logs at 21:00 UTC. A European team that works from 08:00 to 16:00 UTC finished five hours earlier, while the Central team is in the middle of the afternoon. Handovers between them take place around 15:00 UTC, which is 09:00 CST, and you only need to convert CST to UTC once to see it.
A worked incident
The report says: 2:12 p.m., a pump fails; 2:40 p.m., it is restarted; 3:15 p.m., pressure is normal. In UTC the times are 20:12, 20:40 and 21:15. Left in CST, the events seem to occur in the afternoon, whereas the European logs place them in the evening.
By air to Frankfurt
A flight leaving Chicago at 17:30 CST, which is 23:30 UTC, and lasting about eight and a half hours lands at 08:00 UTC, which is 09:00 in Germany. The ticket shows 17:30 and 09:00, so the trip looks like fifteen hours.
Summer time in the Central zone
The American calendar
The United States and Canada move their clocks forward on the second Sunday of March and back on the first Sunday of November: in 2026, 8 March and 1 November. In between, Chicago, Dallas and Houston are on CDT, UTC−5, and the sum becomes five hours.
What logs show
An event at 3:00 p.m. local time is 21:00 UTC in January and 20:00 UTC in July. If a partner writes CST all year, check the date. In Mexico and Central America, however, six hours apply in every month.
What the calculator does
The form above adds six hours, the winter figure. For a date in summer and a place in the United States or Canada, add five instead. UTC is exact in both cases; only the Central wall clock moves.
Energy and crop releases
Weekly petroleum figures
The American energy agency publishes its weekly petroleum status report on Wednesdays at 10:30 a.m. Eastern, which is 9:30 a.m. CST and 15:30 UTC. Traders in Houston read it at breakfast, while traders in London read it in mid-afternoon, an hour before their markets close.
Agricultural progress reports
The weekly crop progress report appears on Mondays at 4:00 p.m. Eastern, which is 3:00 p.m. CST and 21:00 UTC. Farmers in Iowa see it before supper. European grain merchants see it after their offices have shut, so they read it the next morning. A quick convert CST to UTC on the release hour tells you which.
Factories on the Mexican border
Shifts that never change
Plants in Monterrey, Saltillo and Querétaro work on Mexico’s fixed UTC−6 clock. A shift that starts at 6:00 a.m. starts at 12:00 UTC all year. In summer, the factories of Texas are on CDT, so a Texan customer sees the Mexican shift start at 7:00 a.m. on its own wall clock.
Truck crossings
Customs windows at the border are quoted in local time on each side. A truck leaving Monterrey at 14:00 arrives at a crossing near Laredo around 18:00 on the same clock in winter. In summer, the Texan clock is an hour ahead, and the arrival is recorded as 19:00 on the northern side.
Online courses and exams in Texas
Start times
A lecture streamed from a university in Austin at 10:00 a.m. CST is at 16:00 UTC. A student in Britain joins at 16:00 GMT, after lunch. A student in Romania joins at 18:00, in the early evening, and a student in Tokyo at 01:00 the next morning.
Deadlines
An assignment due at 11:59 p.m. CST on Friday is due at 05:59 UTC on Saturday. A student in Europe who hands it in on Saturday at 04:00 UTC is therefore on time. When you convert CST to UTC for a deadline, add the date, not only the hour.
Hurricane evacuation notices
Deadlines on the Gulf coast
Evacuation orders on the Gulf coast often carry local times. A notice that says “mandatory evacuation by 6:00 p.m.” in the hurricane season means 6:00 p.m. CDT, which is 23:00 UTC. A relative in Europe following the news sees that deadline at midnight British Summer Time.
Why it matters
Charity workers and insurers coordinate in UTC. If a message from the field gives a local time without a label, ask whether it is CST or CDT. An hour of difference can affect a rescue plan.
Parcels and mail
Pickup cut-offs
American carriers promise same-day pickup if requested before about 5:00 p.m. local time. For a Central address, that is 23:00 UTC. A European sender who books a pickup at 22:30 UTC has only thirty minutes to spare.
Tracking stamps
Scans show the local time of the depot. A parcel scanned at 3:40 a.m. CST was scanned at 09:40 UTC. A customer in London who sees 09:40 and 03:40 on two different pages is seeing the same moment.
Flights from Mexico City to Europe
A departure at night
A flight that leaves Mexico City at 22:00, which is 04:00 UTC the next day, and lasts about eleven hours lands at 15:00 UTC, which is 16:00 in Madrid. The ticket shows 22:00 and 16:00 the next day, so the trip looks like eighteen hours long, though it takes eleven.
The return
A midday flight from Madrid at 12:00 CET leaves at 11:00 UTC and, after about eleven and a half hours, lands at 22:30 UTC, which is 16:30 in Mexico City. For a traveller who has to convert CST to UTC on both ends, the printed duration is of no use.
Ecotourism in Costa Rica
Early starts
Costa Rica is on UTC−6 all year. Guided walks at the cloud forest start at 6:00 a.m. to catch the wildlife, which is 12:00 UTC. A group that has flown in from Europe feels that time as early afternoon at home. The tour departs and returns on the same clock, so no adjustment is needed in the field.
Booking from afar
Online confirmations show local times. A transfer at 7:30 a.m. is booked for 13:30 UTC. If the travel agency in London has recorded “13:30” and the driver is waiting for “7:30”, they are describing the same moment.
Every hour in one table
CST to UTC
00:00 CST corresponds to 06:00 UTC. 01:00 CST corresponds to 07:00 UTC. 02:00 CST corresponds to 08:00 UTC. 03:00 CST corresponds to 09:00 UTC. 04:00 CST corresponds to 10:00 UTC. 05:00 CST corresponds to 11:00 UTC. 06:00 CST corresponds to 12:00 UTC. 07:00 CST corresponds to 13:00 UTC. 08:00 CST corresponds to 14:00 UTC. 09:00 CST corresponds to 15:00 UTC. 10:00 CST corresponds to 16:00 UTC. 11:00 CST corresponds to 17:00 UTC. 12:00 CST corresponds to 18:00 UTC. 13:00 CST corresponds to 19:00 UTC. 14:00 CST corresponds to 20:00 UTC. 15:00 CST corresponds to 21:00 UTC. 16:00 CST corresponds to 22:00 UTC. 17:00 CST corresponds to 23:00 UTC. 18:00 CST corresponds to 00:00 UTC (next day). 19:00 CST corresponds to 01:00 UTC (next day). 20:00 CST corresponds to 02:00 UTC (next day). 21:00 CST corresponds to 03:00 UTC (next day). 22:00 CST corresponds to 04:00 UTC (next day). 23:00 CST corresponds to 05:00 UTC (next day).
How to read it
Each row shows a Central hour with the matching UTC hour, and says when the date changes. The rows follow the six-hour addition that applies each time you convert CST to UTC.
Half-hour marks
CST to UTC at :30
00:30 CST corresponds to 06:30 UTC. 01:30 CST corresponds to 07:30 UTC. 02:30 CST corresponds to 08:30 UTC. 03:30 CST corresponds to 09:30 UTC. 04:30 CST corresponds to 10:30 UTC. 05:30 CST corresponds to 11:30 UTC. 06:30 CST corresponds to 12:30 UTC. 07:30 CST corresponds to 13:30 UTC. 08:30 CST corresponds to 14:30 UTC. 09:30 CST corresponds to 15:30 UTC. 10:30 CST corresponds to 16:30 UTC. 11:30 CST corresponds to 17:30 UTC. 12:30 CST corresponds to 18:30 UTC. 13:30 CST corresponds to 19:30 UTC. 14:30 CST corresponds to 20:30 UTC. 15:30 CST corresponds to 21:30 UTC. 16:30 CST corresponds to 22:30 UTC. 17:30 CST corresponds to 23:30 UTC. 18:30 CST corresponds to 00:30 UTC (next day). 19:30 CST corresponds to 01:30 UTC (next day). 20:30 CST corresponds to 02:30 UTC (next day). 21:30 CST corresponds to 03:30 UTC (next day). 22:30 CST corresponds to 04:30 UTC (next day). 23:30 CST corresponds to 05:30 UTC (next day).
Why it helps
Many events in the United States start at half past the hour, for example 7:30 p.m. The table gives the matching UTC time at a glance.
Ten readings with minutes
Examples
01:05 CST corresponds to 07:05 UTC. 03:20 CST corresponds to 09:20 UTC. 05:50 CST corresponds to 11:50 UTC. 07:35 CST corresponds to 13:35 UTC. 10:10 CST corresponds to 16:10 UTC. 13:25 CST corresponds to 19:25 UTC. 16:40 CST corresponds to 22:40 UTC. 19:55 CST corresponds to 01:55 UTC (next day). 22:15 CST corresponds to 04:15 UTC (next day). 23:05 CST corresponds to 05:05 UTC (next day).
No change to the minutes
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 UTC?
Central hours seen from Greenwich
06:00 CST corresponds to 12:00 UTC (around midday). 08:00 CST corresponds to 14:00 UTC (afternoon). 10:00 CST corresponds to 16:00 UTC (afternoon). 12:00 CST corresponds to 18:00 UTC (evening). 14:00 CST corresponds to 20:00 UTC (evening). 16:00 CST corresponds to 22:00 UTC (night). 18:00 CST corresponds to 00:00 UTC (night). 20:00 CST corresponds to 02:00 UTC (night). 22:00 CST corresponds to 04:00 UTC (night).
Using the list
The words in brackets describe the part of the day at Greenwich. They help you pick an hour that suits a European team.
American zones towards UTC
How far each zone is from UTC
Add five hours to Eastern time, six to Central, seven to Mountain and eight to Pacific to reach UTC; Alaska needs nine and Hawaii ten. In summer the zones that observe daylight saving need one hour less.
Noon in five cities
When Chicago reads 12:00, New York reads 13:00, Denver 11:00, Los Angeles 10:00 and UTC 18:00. Listing all five spares readers a separate convert CST to UTC.
Dated examples
January
On Friday 16 January, 19:00 CST is 01:00 UTC on Saturday. Add six hours and move to the next date.
March
On Friday 20 March, 19:00 in Chicago is CDT, which is 00:00 UTC on Saturday. Add five hours.
August
On Friday 14 August, 19:00 CDT is 00:00 UTC on Saturday. In Mexico City, 19:00 would be 01:00 UTC.
November
On Friday 6 November, 19:00 CST is 01:00 UTC on Saturday. The United States returned to standard time on 1 November.
Checklist: how to convert CST to UTC
Preparation
Label and location
CST, CDT or CT? In the United States and Canada, from 8 March to 1 November, the label is CDT, UTC−5. In Mexico and Central America it is UTC−6 all year.
Clock format
Twenty-four hours is simplest. 7:30 p.m. is 19:30, and 12:00 a.m. is 00:00.
The sum
Adding the offset
Six hours in winter. When the total passes 24:00, subtract 24 and advance the date.
Sanity check
18:00 CST has to give midnight UTC. If your method gives anything else, something is off.
Winter sports and the Upper Midwest
Opening hours in Minnesota and Wisconsin
Ski hills and ice rinks in the Upper Midwest open at about 9:00 a.m. CST, which is 15:00 UTC. Evening sessions start at 6:00 p.m., or 00:00 UTC. Hockey games at 7:00 p.m. CST begin at 01:00 UTC, so viewers in Europe see them in the middle of the night.
Weather and closing times
Cold-weather closures are announced for the next morning. A notice that says schools will open at 10:00 a.m. means 16:00 UTC. A parent in Europe following a child’s exchange programme should convert CST to UTC for each announcement to avoid missing it.
Mistakes when you convert CST to UTC
Wrong direction
UTC is in front of Chicago, so the answer should be larger than the Central hour. A smaller number means a subtraction slipped in.
Winter figure in summer
For American places the summer gap is five hours. A July notice with CST is normally CDT.
The date left behind
22:00 CST is 04:00 UTC on the next date. If the date stays put, the answer is a full day out.
The wrong CST
China Standard Time is UTC+8 and Cuba Standard Time is UTC−5, so check the country.
Frequently asked questions
What is the gap between CST and UTC?
Six hours: UTC is in front.
Which formula applies when I convert CST to UTC?
Central hour plus six, minus 24 if the total reaches 24.
How much is 9:30 a.m. CST in UTC?
15:30 UTC.
When do I add five hours instead?
When the place is in the United States or Canada and the date lies between the second Sunday of March and the first Sunday of November.
Does the page keep my input?
No. Everything is processed in your browser.
More time zone converters
Further pages: Convert CST to EST, Convert CST to EET, Convert WET to UTC, Convert EET to UTC, Convert UTC to CET, Convert GMT to CST, Convert GMT to CET, Convert EET to CET, Convert EST to CET. The opposite direction lives at Convert UTC to CST.
To summarise, a request to convert CST to UTC means adding six hours, minding the 6 p.m. threshold and allowing for North American summer time. The work stays on your device, without sign-up.