What is the time difference between IRST and KST?

Korea Standard Time (KST) is 5 hours and 30 minutes ahead of Iran Standard Time (IRST). IRST uses a UTC offset of UTC+3:30, while KST uses UTC+9. For example, when it's 9:00 AM in IRST, it's 2:30 PM in KST. This difference remains constant year-round since neither timezone observes daylight saving time. Use the conversion table above to see the exact time for each hour of the day.

How do I convert IRST to KST?

To convert IRST to KST, add 5 hours and 30 minutes to the IRST time. For example, 9:00 AM IRST is 2:30 PM KST, and 5:00 PM IRST is 10:30 PM KST. Since neither timezone observes DST, this conversion stays the same all year. You can also use the interactive converter above for quick, accurate results.

What time is it in KST when it's noon in IRST?

When it's 12:00 PM (noon) in IRST, it's 5:30 PM in KST. This is because KST is 5 hours and 30 minutes ahead of IRST. Similarly, when it's 6:00 PM in IRST, it's 11:30 PM in KST. This relationship is constant throughout the year. The color-coded conversion table above shows every hour mapped between both timezones.

How many hours ahead is KST from IRST?

KST is 5 hours and 30 minutes ahead of IRST. This means when it's 9:00 AM in IRST, it's 2:30 PM in KST, and when it's midnight in IRST, it's 5:30 AM in KST. This offset is constant throughout the year since neither timezone uses daylight saving time. The conversion table above provides a complete hour-by-hour mapping.

Is KST ahead or behind IRST?

KST is ahead of IRST by 5 hours and 30 minutes. Clocks in KST show a later time than IRST, meaning the day starts earlier in KST relative to IRST. For example, when it's morning in IRST, it's later in the morning in KST. This difference stays the same year-round.

Does IRST observe daylight saving time?

No, Iran Standard Time does not observe daylight saving time. The UTC offset of UTC+3:30 remains the same year-round, which simplifies time conversions. Regions using IRST keep their clocks unchanged regardless of the season.

Does KST observe daylight saving time?

No, Korea Standard Time does not observe daylight saving time. The UTC offset of UTC+9 remains the same year-round, making time conversions to KST more predictable. Countries and regions in this timezone keep their clocks unchanged regardless of the season.

What is the best time to call from IRST to KST?

The best time for a call between IRST and KST is during overlapping business hours (9 AM – 5 PM) in both timezones. To reach someone in KST during their work day, call between 3:30 AM and 11:30 AM your IRST time. Avoid calling too early or late, as the 5 hours and 30 minutes difference means your evening could be their late night. Check the color-coded conversion table above — green hours indicate business hours in both zones, making it easy to find the ideal time.

Do IRST and KST ever have the same time?

No, IRST and KST are always 5 hours and 30 minutes apart and never display the same clock time simultaneously. Neither timezone observes DST, so the difference is constant year-round with no seasonal variation. The 5 hours and 30 minutes offset is determined by their fixed positions relative to the Prime Meridian (UTC). You can always rely on this consistent difference when planning across these timezones.

IRST to KST Converter

Convert Iran Standard Time to Korea Standard Time. See the hour-by-hour conversion table below.

Timezone Details

Tehran

3:54 AM

Friday, April 3, 2026

Tehran (UTC+03:30)

Korea Standard Time

9:24 AM

Friday, April 3, 2026

KST (UTC+09:00)

Difference: +5h 30m

KST DST: No

24-Hour Overview

Tehran — 24-hour overview

12a12a

3a3a

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

NightMorningBusinessEvening

KST — 24-hour overview

5a5a

8a8a

10a

11a11a

12p

2p2p

5p5p

8p8p

10p

11p11p

12a

2a2a

NightMorningBusinessEvening

Frequently Asked Questions

Related Conversions

KST to IRST

Cities in These Timezones

IRST Cities

Tehran

KST Cities

Seoul Busan

More Tools

Compare IRST & KST Plan a Meeting (IRST & KST)See on Map

Learn More

How Time Zones Work Understanding DST Timezone Abbreviations

External Resources

Korea Standard Time on Wikipedia IANA Time Zone Database