IST to AEST
Mumbai to Sydney.
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All date & timeQuestions
What time is AEST when it is 12:00 IST?
17:30. Australian Eastern Time is 5 hours 30 minutes ahead of India Standard Time in January and 4 hours 30 minutes ahead of it in July. The gap moves because Sydney observes daylight saving and Mumbai does not, so the difference between them is not a fixed number. A 9-to-5 day in Mumbai overlaps a 9-to-5 day in Sydney for 2.5 hours, between 09:00 and 11:30 IST.
Is the difference between IST and AEST the same all year?
No, and this is the pair where that matters. Australian Eastern Time is 5 hours 30 minutes ahead of India Standard Time in January and 4 hours 30 minutes ahead of it in July. The gap moves because Sydney observes daylight saving and Mumbai does not, so the difference between them is not a fixed number. Booking a recurring call across these two and assuming one number will drift by an hour twice a year — check the date, not just the zones.
What do IST and AEST actually stand for?
IST is India Standard Time, the zone covering Mumbai, currently UTC+5:30 in January. AEST is Australian Eastern Time, covering Sydney, at UTC+11. One of a handful of zones offset by half an hour rather than a whole one — UTC+5:30 for the entire country, from Gujarat to Arunachal Pradesh. India has no daylight saving, so the offset is the same all year.
Anything worth knowing about Australian Eastern Time?
Southern hemisphere daylight saving runs October to April — the opposite half of the year to Europe and North America. So the gap between Sydney and London swings by two hours across the year, not one.
When is a good time to call between Mumbai and Sydney?
A 9-to-5 day in Mumbai overlaps a 9-to-5 day in Sydney for 2.5 hours, between 09:00 and 11:30 IST. If the call has to happen outside that, the fairer arrangement is usually to alternate which side takes the awkward hour rather than always asking the same one.
How it works, and more about ist → aest
The difference, and whether you can rely on it
In January, Australian Eastern Time is 5 hours 30 minutes ahead of India Standard Time — UTC+5:30 against UTC+11. In July it is 4 hours 30 minutes ahead instead. That is the part worth carrying away: this is not a pair you can memorise a single number for.
Why the gap moves
Sydney observes daylight saving; Mumbai does not. So the clocks in one city move twice a year while the other stays put, and the distance between them changes with them. Any calculation you did in one season is wrong in the other. The converter above uses the date you give it rather than today’s offset, which is the only way to get a future meeting right when it falls on the other side of a changeover.
When you can both be at a desk
A standard working day in Mumbai overlaps one in Sydney between 09:00 and 11:30 IST — 3 hours. Anything outside that asks somebody to start early or finish late.
Reading the abbreviations literally will mislead you
IST strictly means one fixed offset, but almost nobody uses it that way. People write it to mean the time in Mumbai, which shifts if the city observes daylight saving, which this one does not. This page follows the common usage rather than the strict one, because the strict reading gives an answer that is wrong for a good part of the year.
One of a handful of zones offset by half an hour rather than a whole one — UTC+5:30 for the entire country, from Gujarat to Arunachal Pradesh. India has no daylight saving, so the offset is the same all year. Southern hemisphere daylight saving runs October to April — the opposite half of the year to Europe and North America. So the gap between Sydney and London swings by two hours across the year, not one.
Scheduling something recurring
For a one-off, the converter above is the whole job. For a standing meeting across these two zones, where the gap changes, it is worth putting the invitation in a calendar that stores the zone rather than the time — then the changeover is handled for you and nobody has to remember. If you are trying to find a slot across more than two places at once, the meeting planner shows a whole day at a glance instead.