Does it handle Daylight Saving Time?

Yes, the tool automatically adjusts for Daylight Saving Time based on the specific date you select, ensuring accurate conversions year-round.

Can I add multiple cities?

Yes, you can add as many cities as you need to the dashboard to compare times across your entire global network simultaneously.

IRST to Osaka

+5h 30m

IRST

IRSTSOURCE

UTC+03:30

HH12

MM00

12:00 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Osaka

JST

Japan · UTC+09:00

HH05

MM30

17:30 (24-hr)

12 AM6 AM12 PM6 PM12 AM

Quick Reference

Time Conversion Table

IRST

Osaka

12:00 AM

5:30 AM

2:00 AM

7:30 AM

4:00 AM

9:30 AM

6:00 AM

11:30 AM

8:00 AM

1:30 PM

10:00 AM

3:30 PM

12:00 PM

5:30 PM

2:00 PM

7:30 PM

4:00 PM

9:30 PM

6:00 PM

11:30 PM

8:00 PM

1:30 AM+1

10:00 PM

3:30 AM+1

Green rows indicate typical business hours (9 AM - 5 PM)

IRST and JST on the World Map

The map below highlights the IRST (Iran Standard Time) and JST (Japan Standard Time) timezone regions across the globe.

IRST Zone

→

JST Zone

Explore all world timezones interactively →

IRST – Iran Standard Time

UTC+03:30

Iran Standard Time (IRST) is the time zone for Iran, 3 hours and 30 minutes ahead of UTC.

Countries in IRST

Iran

Major Cities in IRST

TehranIsfahanMashhadTabrizShirazKaraj

Key Facts about IRST

•IRST is one of only a few time zones with a 30-minute offset.
•Iran observes daylight saving time, switching to IRDT (UTC+04:30).
•Tehran has a metropolitan population of over 16 million.

Daylight Saving:Yes – switches to IRDT

Learn more about IRST on Wikipedia

JST – Japan Standard Time

UTC+09:00

Japan Standard Time (JST) is the time zone for Japan, 9 hours ahead of UTC.

Countries in JST

Japan

Major Cities in JST

TokyoOsakaYokohamaNagoyaSapporoKyotoKobeFukuokaHiroshima

Key Facts about JST

•Japan does not observe daylight saving time.
•Tokyo is the most populous metropolitan area in the world.
•The Tokyo Stock Exchange operates from 9:00 AM to 3:00 PM JST.
•JST is 14 hours ahead of EST and 9 hours ahead of GMT.

Daylight Saving:No – UTC+09:00 year-round

Learn more about JST on Wikipedia

About Osaka

Wikipedia

Osaka operates on Japan Standard Time (JST), UTC+9. As Japan's second economic center and a manufacturing hub, Osaka shares business hours with Tokyo.

Population:2.8 million

Metro:19 million

Business Hours:9:00 AM - 6:00 PM JST

Currency:JPY (¥)

Stock Exchange:OSE (Osaka Exchange - derivatives)

Key Landmarks

Osaka CastleDotonboriUniversal Studios JapanShitennoji TempleUmeda Sky Building

Did You Know?

Osaka Castle was originally built in 1583 and has been rebuilt several times.

Learn more about JST timezone →

Everything You Need to Know About IRST and Osaka Time

IRST runs on Iran Standard Time (IRST) at UTC+03:30. Osaka runs on Japan Standard Time (JST) at UTC+09:00. That puts IRST 5 hours 30 minutes ahead of Osaka — a difference of +5h 30m at the current offsets.

In practice, when it is 9:00 AM in IRST it is 2:30 PM in Osaka. Midnight in IRST is 5:30 AM in Osaka. Neither zone observes daylight saving time, so the offset between them stays constant all year.

IRST to Osaka time conversion table

IRST (IRST)	Osaka (JST)	Day
12:00 AM	5:30 AM	same day
6:00 AM	11:30 AM	same day
7:00 AM	12:30 PM	same day
8:00 AM	1:30 PM	same day
9:00 AM	2:30 PM	same day
12:00 PM	5:30 PM	same day
3:00 PM	8:30 PM	same day
5:00 PM	10:30 PM	same day
6:00 PM	11:30 PM	same day
9:00 PM	2:30 AM	next day

Why people convert IRST to Osaka time

Scheduling a call from IRST to Osaka: a 10:00 AM start in IRST lands at 3:30 PM in Osaka, so you can confirm the slot without doing the arithmetic yourself.
Finding shared working hours: both IRST and Osaka are inside the 9-to-5 working day between 9:00 AM and 11:30 AM IRST time (2:30 PM–5:00 PM JST). That is roughly 2 hours 30 minutes of usable overlap.
Coordinating a IRST-based team with Osaka contacts: quoting times in the other side's local clock — not your own — removes the single biggest source of missed meetings.

Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a +5h 30m gap is not.
Block 9:00 AM–11:30 AM IRST as the recurring meeting window if you work primarily from IRST and need Osaka colleagues present.

About IRST (Iran Standard Time)

Iran Standard Time (IRST) is one of the few time zones with a 30-minute offset. Iran observes daylight saving time (IRDT, UTC+04:30) from late March to late September. Tehran, the capital, is one of the largest cities in the Middle East.

About JST (Japan Standard Time)

Japan Standard Time (JST) is the standard time zone for all of Japan. Japan does not observe daylight saving time. JST is 9 hours ahead of UTC and 14 hours ahead of EST. The Tokyo Stock Exchange, the world's third largest by market capitalization, operates on JST. South Korea uses the same offset (KST) but it is a distinct time zone.

Best time to call between IRST and Osaka

Both IRST and Osaka sit inside the 9 AM – 5 PM working day between 9:00 AM–11:30 AM IRST, which is 2:30 PM–5:00 PM JST. That gives roughly 2 hours and 30 minutes of shared time — the safest window for a live call or meeting.

Business hours overlap

IRST and Osaka overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.

IRST is 5 hours 30 minutes ahead of Osaka (IRST UTC+03:30 → JST UTC+09:00). The shared working window is 9:00 AM–11:30 AM IRST. Remember to re-check around daylight-saving transitions.

Learn More About Time

Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:

⏳

History of Timekeeping

From sundials to atomic clocks - 5000 years of measuring time

🌍

How Time Zones Work

UTC, offsets, and why zones don't follow straight lines

☀️

Daylight Saving Time

DST dates, which countries observe it, and the ongoing debate

Frequently Asked Questions

What is the time difference between IRST and Osaka?

IRST (IRST, UTC+03:30) is 5 hours 30 minutes ahead of Osaka (JST, UTC+09:00). The gap is currently +5h 30m.

How do I convert IRST time to Osaka time?

Add +5h 30m to IRST local time. For example, 9:00 AM in IRST is 2:30 PM in Osaka.

What time is it in Osaka right now?

Osaka uses JST at UTC+09:00. Use the live converter at the top of this page — it updates in real time and already accounts for the +5h 30m offset from IRST.

What is the best time to call Osaka from IRST?

Call between 9:00 AM and 11:30 AM IRST — that maps to 2:30 PM–5:00 PM JST and keeps both parties inside the working day.

Which is ahead, IRST or Osaka?

IRST is 5 hours 30 minutes ahead of Osaka. When it is 12:00 PM in IRST it is 5:30 PM in Osaka.

Do IRST and Osaka use different time zones?

IRST uses IRST at UTC+03:30, while Osaka (Japan) uses JST at UTC+09:00. The IANA identifiers are Asia/Tehran and Asia/Tokyo.

Does daylight saving time affect the IRST–Osaka difference?

Neither zone observes daylight saving time, so the +5h 30m offset between IRST and Osaka is fixed all year.

Which other cities share IRST's time zone?

IRST also covers Tehran, Isfahan, Mashhad, Tabriz, Shiraz, Karaj.

Which countries use IRST, IRST's zone?

IRST is used in Iran.

Is there a day difference between IRST and Osaka?

Not normally. The +5h 30m gap only pushes the date over for late-evening times.

What is the time difference between IRST and Osaka?

Osaka is +5h 30m from IRST.

What timezone is IRST in?

IRST operates on its local timezone.

What timezone is Osaka in?

Osaka operates on Japan Standard Time (JST), UTC+9. As Japan's second economic center and a manufacturing hub, Osaka shares business hours with Tokyo.