IRST to CAT
-1h 30mIRST
IRSTSOURCECAT
CATGreen rows indicate typical business hours (9 AM - 5 PM)
IRST and CAT on the World Map
The map below highlights the IRST (Iran Standard Time) and CAT (Central Africa Time) timezone regions across the globe.
IRST – Iran Standard Time
UTC+03:30Iran Standard Time (IRST) is the time zone for Iran, 3 hours and 30 minutes ahead of UTC.
- •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.
CAT – Central Africa Time
UTC+02:00Central Africa Time (CAT, UTC+02:00) covers Zimbabwe, Zambia, Mozambique, Malawi and neighbouring countries.
- •Central Africa Time is fixed at UTC+02:00 with no daylight saving.
- •CAT matches South Africa Standard Time (SAST) all year.
- •It is the same offset as Central European Time in winter.
- •Harare is level with Johannesburg and one hour ahead of Lagos.
Understanding the -1h 30m Gap: IRST vs CAT
IRST runs on Iran Standard Time (IRST) at UTC+03:30. CAT runs on Central Africa Time (CAT) at UTC+02:00. That puts IRST 1 hour 30 minutes behind CAT — a difference of -1h 30m at the current offsets.
In practice, when it is 9:00 AM in IRST it is 7:30 AM in CAT. Midnight in IRST is 10:30 PM in CAT. Neither zone observes daylight saving time, so the offset between them stays constant all year.
IRST to CAT time conversion table
| IRST (IRST) | CAT (CAT) | Day |
|---|---|---|
| 12:00 AM | 10:30 PM | previous day |
| 6:00 AM | 4:30 AM | same day |
| 7:00 AM | 5:30 AM | same day |
| 8:00 AM | 6:30 AM | same day |
| 9:00 AM | 7:30 AM | same day |
| 12:00 PM | 10:30 AM | same day |
| 3:00 PM | 1:30 PM | same day |
| 5:00 PM | 3:30 PM | same day |
| 6:00 PM | 4:30 PM | same day |
| 9:00 PM | 7:30 PM | same day |
Why people convert IRST to CAT time
- Scheduling a call from IRST to CAT: a 10:00 AM start in IRST lands at 8:30 AM in CAT, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both IRST and CAT are inside the 9-to-5 working day between 10:30 AM and 5:00 PM IRST time (9:00 AM–3:30 PM CAT). That is roughly 6 hours 30 minutes of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in IRST is 6:30 PM in CAT makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM IRST" is unambiguous; "3 PM" across a -1h 30m gap is not.
- Block 10:30 AM–5:00 PM IRST as the recurring meeting window if you work primarily from IRST and need CAT 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 CAT (Central Africa Time)
Central Africa Time (CAT) is fixed at UTC+02:00 all year across a broad belt of southern and central Africa, including Zimbabwe, Zambia, Mozambique, Malawi, Rwanda, Burundi and the eastern Democratic Republic of the Congo. None of these countries observes daylight saving time, so CAT never shifts. It is the same offset as South Africa Standard Time (SAST) and the winter version of Central European Time, which makes CAT a convenient bridge between African, European and Middle Eastern schedules — Harare is level with Johannesburg all year and one hour ahead of Lagos.
Best time to call between IRST and CAT
Both IRST and CAT sit inside the 9 AM – 5 PM working day between 10:30 AM–5:00 PM IRST, which is 9:00 AM–3:30 PM CAT. That gives roughly 6 hours and 30 minutes of shared time — the safest window for a live call or meeting.
Business hours overlap
IRST and CAT share 6 hours of working-hours overlap (10:30 AM–5:00 PM IRST), so scheduling a live meeting is straightforward.
IRST is 1 hour 30 minutes behind CAT (IRST UTC+03:30 → CAT UTC+02:00). The shared working window is 10:30 AM–5:00 PM 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:
Frequently Asked Questions
What is the time difference between IRST and CAT?
IRST (IRST, UTC+03:30) is 1 hour 30 minutes behind CAT (CAT, UTC+02:00). The gap is currently -1h 30m.
How do I convert IRST time to CAT time?
Add -1h 30m to IRST local time. For example, 9:00 AM in IRST is 7:30 AM in CAT.
What time is it in CAT right now?
CAT uses CAT at UTC+02:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -1h 30m offset from IRST.
What is the best time to call CAT from IRST?
Call between 10:30 AM and 5:00 PM IRST — that maps to 9:00 AM–3:30 PM CAT and keeps both parties inside the working day.
Which is behind, IRST or CAT?
IRST is 1 hour 30 minutes behind CAT. When it is 12:00 PM in IRST it is 10:30 AM in CAT.
Does daylight saving time affect the IRST–CAT difference?
Neither zone observes daylight saving time, so the -1h 30m offset between IRST and CAT 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 CAT?
Not normally. The -1h 30m gap only pushes the date over the previous day.
What is the time difference between IRST and CAT?
CAT is -1h 30m from IRST.
What timezone is IRST in?
IRST operates on its local timezone.
What timezone is CAT in?
CAT operates on its local timezone.
Which countries use IRST (Iran Standard Time)?
IRST is used in Iran.
Does IRST observe daylight saving time?
Yes, IRST switches to IRDT during summer months.
What are some interesting 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).
Which cities are in the CAT timezone?
Major cities in the CAT timezone include Harare, Lusaka, Maputo, Lilongwe, Kigali.
What is the UTC offset for CAT?
Central Africa Time (CAT) is at UTC+02:00.
What should I know about the CAT timezone?
Central Africa Time is fixed at UTC+02:00 with no daylight saving. CAT matches South Africa Standard Time (SAST) all year.
When is it midnight in IRST, what time is it in CAT?
When it is 12:00 AM (midnight) in IRST (IRST), it is -1h 30m later in CAT (CAT).
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