Karaj, Iran · UTC+3:30 ☆

Karaj is one of the most populated cities in Iran, sitting just 20 kilometers west of Tehran in the Alborz mountain foothills. It shares Iran Standard Time, a clock that stands apart from most of the world by being offset at 30 minutes: UTC+3:30 in winter, UTC+4:30 during Iran’s daylight saving period.

commuting to Tehran, living on Iranian time

Iran’s half-hour offset dates to 1935, when the country standardized its clocks to better match solar noon for the country’s geographic center. Most of the world rounds to whole hours. Iran, like India and a handful of others, did not. It’s a small act of non-conformity preserved across nearly a century.

Karaj grew rapidly in the second half of the 20th century, absorbing Tehran’s overspill into a city of over 1.8 million. Many residents commute to Tehran, which means their day is structured around traffic more than the clock. The highway between Karaj and Tehran is famously congested, and rush hour here is less a time of day than a permanent condition.

Iran observes daylight saving, switching clocks in late March and reverting in late September. The dates follow the Iranian calendar (Solar Hijri), which means the transitions don’t fall on the same Gregorian dates each year.

9am in Karaj is 5:30am in London in winter, a reminder that the half-hour offset cascades through every time conversion.

Sources

• IANA Time Zone Database - Asia/Tehran
• Iran Meteorological Organization