Live offset · Year-round DST · Shareable URL

Time difference
Chicago and Tehran

Live clocks (CST ↔ IRST), the current gap, month-by-month offset changes, and a full 24-hour map from Chicago to Tehran.

1

Live gap

See the current offset between Chicago and Tehran, with IANA-backed clocks updating every second.

2

Year-round chart

DST can shift the gap by an hour twice a year—the 2026 month table shows every change.

3

Hour-by-hour

Scroll the 24-hour table to map any civil hour in Chicago into Tehran with day-shift cues.

Time difference workspace

How Chicago and Tehran line up today.

2 cities · live offsetGap shifts yearly
City pair

Chicago Tehran

Tehran is 8.5h ahead of Chicago at this moment. Compare live clocks, seasonal DST shifts, and hour-by-hour conversions below.

Live offsetIANA zones · updates automatically
Chicago
America/Chicago
ZoneCST / CDT
Offset nowUTC-5
Hour gap
+8:30

TehranChicago

Tehran
Asia/Tehran
ZoneIRST
Offset nowUTC+3:30
About this pairUseful when planning calls or docs

Time difference between Chicago and Tehran: Tehran is currently 9.5 hours ahead of Chicago.

This difference is not constant: in winter Chicago is 9.5 hours behind Tehran, while in summer (when one or both observe DST) the gap shifts to 8.5 hours behind. The monthly table below shows the exact offset gap month by month. For practical scheduling, jump to the best-time-to-meet page or the 24-hour conversion table below.

Jump aheadPick the view you need next
Best time to meetMonthly offsets24-hour table
Live clocks workspace

Clocks side by side.

Updates every second
Right nowAmerica/Chicago · Asia/Tehran
Chicago
America/Chicago
Live time
--:--
OffsetUTC-5
AbbreviationCST / CDT
Observes DST
Tehran
Asia/Tehran
Live time
--:--
OffsetUTC+3:30
AbbreviationIRST
No DST
Relationship

Tehran is 8.5h ahead of Chicago.

DST rules can widen or shrink this gap for a few weeks each spring and autumn—the month table below shows how many hours Tehran sits ahead of or behind Chicago through the calendar year.

Next stepsPlan overlap or convert zones
Best time to meet →CST → IRST →Overlap Finder →
Year-round

Offset changes by month

Sampled mid-month for 2026. Compares Tehran versus Chicago; a value of +3h means Tehran is three hours ahead of Chicago.

2026 calendar

Month-by-month gap

MonthDifference (Tehran vs Chicago)
January+9.5h
February+9.5h
March+8.5h
April+8.5h
May+8.5h
June+8.5h
July+8.5h
August+8.5h
September+8.5h
October+8.5h
November+9.5h
December+9.5h
Hour by hour

24-hour conversion table

Every civil hour in Chicago mapped into Tehran; day-shift cues follow active DST for both zones today.

ChicagoTehran

Hourly wall-clock map for today — midnight crossings show as day shifts.

Chicago with part-of-day icon
Tehran arrow and converted time
Day
  • 00:00
    08:30
    Same day
  • 01:00
    09:30
    Same day
  • 02:00
    10:30
    Same day
  • 03:00
    11:30
    Same day
  • 04:00
    12:30
    Same day
  • 05:00
    13:30
    Same day
  • 06:00
    14:30
    Same day
  • 07:00
    15:30
    Same day
  • 08:00
    16:30
    Same day
  • 09:00
    17:30
    Same day
  • 10:00
    18:30
    Same day
  • 11:00
    19:30
    Same day
  • 12:00
    20:30
    Same day
  • 13:00
    21:30
    Same day
  • 14:00
    22:30
    Same day
  • 15:00
    23:30
    Same day
  • 16:00
    00:30
    Next day
  • 17:00
    01:30
    Next day
  • 18:00
    02:30
    Next day
  • 19:00
    03:30
    Next day
  • 20:00
    04:30
    Next day
  • 21:00
    05:30
    Next day
  • 22:00
    06:30
    Next day
  • 23:00
    07:30
    Next day
Uses your browser's IANA zone data — choose another date in the converter for historical or future days.
Keep exploring

Related pages

More time-difference routes, pairwise best times, triple-city overlaps, and conversions tied to Chicago, Tehran, or this corridor.

FAQ

Frequently asked questions

Offsets between Chicago and Tehran, DST shifts, scheduling, and how we source timezone data—plus how to share this page.

Currently, Tehran is 8.5h ahead of Chicago. This may change through the year if either city observes Daylight Saving Time.