IST to CAT Time Converter
CAT is 3 hours and 30 minutes behind IST. IST is UTC+5:30, and CAT is UTC+2:00.
Best Time to Call Between IST and CAT
Both zones are inside normal business hours between 1:00 PM and 5:00 PM IST — that's 9:30 AM to 1:30 PM CAT. That's a 4-hour window.
both at work IST only CAT only neither — hours along the strip are IST.
Common Times Converted
IST on the left, CAT on the right.
IST to CAT: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| IST | CAT | Working hours |
|---|---|---|
| 12:00 AM | 8:30 PM prev day | — |
| 1:00 AM | 9:30 PM prev day | — |
| 2:00 AM | 10:30 PM prev day | — |
| 3:00 AM | 11:30 PM prev day | — |
| 4:00 AM | 12:30 AM | — |
| 5:00 AM | 1:30 AM | — |
| 6:00 AM | 2:30 AM | — |
| 7:00 AM | 3:30 AM | — |
| 8:00 AM | 4:30 AM | — |
| 9:00 AM | 5:30 AM | IST only |
| 10:00 AM | 6:30 AM | IST only |
| 11:00 AM | 7:30 AM | IST only |
| 12:00 PM | 8:30 AM | IST only |
| 1:00 PM | 9:30 AM | Both zones |
| 2:00 PM | 10:30 AM | Both zones |
| 3:00 PM | 11:30 AM | Both zones |
| 4:00 PM | 12:30 PM | Both zones |
| 5:00 PM | 1:30 PM | CAT only |
| 6:00 PM | 2:30 PM | CAT only |
| 7:00 PM | 3:30 PM | CAT only |
| 8:00 PM | 4:30 PM | CAT only |
| 9:00 PM | 5:30 PM | — |
| 10:00 PM | 6:30 PM | — |
| 11:00 PM | 7:30 PM | — |
What IST and CAT Actually Are
IST — India Standard Time
Mumbai, Delhi, Bengaluru, Chennai, Kolkata, Hyderabad — and Colombo. Standing at UTC+5:30 as written, and the region does not change its clocks, so that offset holds all year. IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.
India runs a single time zone across a country wide enough for two, which is why sunrise in the north-east can come nearly two hours before Mumbai's. Proposals for a second zone resurface regularly and have never been adopted.
CAT — Central Africa Time
Harare, Lusaka, Maputo, Khartoum. Standing at UTC+2:00 as written, and the region does not change its clocks, so that offset holds all year.
Central Africa Time has never used daylight saving. Near the equator the length of the day changes so little that there would be nothing to shift.
What This Means in Practice
Expect times on the half hour
IST sits on a 30-minute offset rather than a whole hour, so a round number on one side is never a round number on the other. A 9:00 meeting becomes 30 minutes past the hour, which is exactly the detail calendar invitations get wrong when someone converts in their head.
A gap you can rely on
Neither region changes its clocks, so this difference holds every day of the year. A recurring meeting booked once stays correct — worth knowing, because most cross-border pairs cannot say that.
Major Cities in Each Zone
Cities on IST
Cities on CAT
Frequently Asked Questions
What is the time difference between IST and CAT?
CAT is 3 hours and 30 minutes behind IST.
What is 9:00 AM IST in CAT?
9:00 AM IST is 5:30 AM CAT.
What are the best hours to schedule a call between IST and CAT?
Between 1:00 PM and 5:00 PM IST, which is 9:30 AM to 1:30 PM CAT. Both sides are inside normal business hours through that window.
Does the difference between IST and CAT change during the year?
No. Neither region changes its clocks, so this gap is fixed all year round.
Does IST always mean India Standard Time?
IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.