ACST to JST: ACST is 30 minutes ahead of JST
Australian Central Time is 30 minutes ahead of Japan Standard Time right now. It is 12:13 am ACST in Australian Central and 11:43 pm JST in Japan, which is already the previous day there.
Convert a specific time from ACST to JST
Pick any time and date to convert it both ways. The conversion runs in your browser against the real zone rules, so a date inside a daylight saving period gets that period's offset rather than today's.
What is the time difference between ACST and JST?
Japan Standard Time is 30 minutes behind Australian Central Time. To go from ACST to JST you subtract 30 minutes. That gap is not fixed. Across 2026 the distance between these two zones takes 2 different values, from 30 minutes to 1 hour 30 minutes, because Australian Central moves its clocks and Japan does not. This page recomputes it rather than assuming.
ACST to JST conversion table
Every hour of Saturday, September 26, 2026 in Australian Central, with the matching reading in Japan. 1 of the 24 hours land on a different calendar date in Japan, which is the part people get wrong when they schedule across this pair.
| ACST | ACST 24h | JST | JST 24h | Date |
|---|---|---|---|---|
| 12:00 am | 00:00 | 11:30 pm | 23:30 | the previous day |
| 1:00 am | 01:00 | 12:30 am | 00:30 | same day |
| 2:00 am | 02:00 | 1:30 am | 01:30 | same day |
| 3:00 am | 03:00 | 2:30 am | 02:30 | same day |
| 4:00 am | 04:00 | 3:30 am | 03:30 | same day |
| 5:00 am | 05:00 | 4:30 am | 04:30 | same day |
| 6:00 am | 06:00 | 5:30 am | 05:30 | same day |
| 7:00 am | 07:00 | 6:30 am | 06:30 | same day |
| 8:00 am | 08:00 | 7:30 am | 07:30 | same day |
| 9:00 am | 09:00 | 8:30 am | 08:30 | same day |
| 10:00 am | 10:00 | 9:30 am | 09:30 | same day |
| 11:00 am | 11:00 | 10:30 am | 10:30 | same day |
| 12:00 pm | 12:00 | 11:30 am | 11:30 | same day |
| 1:00 pm | 13:00 | 12:30 pm | 12:30 | same day |
| 2:00 pm | 14:00 | 1:30 pm | 13:30 | same day |
| 3:00 pm | 15:00 | 2:30 pm | 14:30 | same day |
| 4:00 pm | 16:00 | 3:30 pm | 15:30 | same day |
| 5:00 pm | 17:00 | 4:30 pm | 16:30 | same day |
| 6:00 pm | 18:00 | 5:30 pm | 17:30 | same day |
| 7:00 pm | 19:00 | 6:30 pm | 18:30 | same day |
| 8:00 pm | 20:00 | 7:30 pm | 19:30 | same day |
| 9:00 pm | 21:00 | 8:30 pm | 20:30 | same day |
| 10:00 pm | 22:00 | 9:30 pm | 21:30 | same day |
| 11:00 pm | 23:00 | 10:30 pm | 22:30 | same day |
What are the best hours to schedule a call between ACST and JST?
7 hours of the standard 9:00 am to 5:00 pm working day line up in both zones, from 10:00 am ACST to 5:00 pm ACST. In Japan that window reads 9:30 am to 4:30 pm. Outside it, one side is either not yet at their desk or already gone.
| ACST | JST | Working hours | Note |
|---|---|---|---|
| 10:00 am | 9:30 am | both sides | mid morning in Australian Central, mid morning in Japan |
| 11:00 am | 10:30 am | both sides | mid morning in Australian Central, mid morning in Japan |
| 12:00 pm | 11:30 am | both sides | noon in Australian Central, mid morning in Japan |
| 1:00 pm | 12:30 pm | both sides | afternoon in Australian Central, noon in Japan |
| 2:00 pm | 1:30 pm | both sides | afternoon in Australian Central, afternoon in Japan |
| 3:00 pm | 2:30 pm | both sides | afternoon in Australian Central, afternoon in Japan |
| 4:00 pm | 3:30 pm | both sides | afternoon in Australian Central, afternoon in Japan |
Does daylight saving change ACST to JST?
Australian Central Time is currently on ACST and changes next on Sunday, October 4, 2026, when the clock jumps forward from 1:59 am to 3:00 am and the offset moves from UTC+9:30 to UTC+10:30.
Japan Standard Time does not move its clocks at all, so its UTC+9 offset holds every day of the year.
Because the two sides do not move together, the answer to this conversion changes during the year. For part of the year the gap is 30 minutes and for the rest it is 1 hour 30 minutes. The table above is built for today, not for an average day.
Is ACST ahead of or behind JST?
ACST is ahead of JST by 30 minutes: when it is 12:00 pm in Australian Central, it is 11:30 am in Japan. One wrinkle worth knowing: ACST and ACDT are two names for the same zone, not two zones. Australian Central Time reads ACST in winter and ACDT in summer. When somebody types "acst to jst" they nearly always mean the zone rather than the literal winter offset, so this page resolves ACST to Australia/Adelaide and JST to Asia/Tokyo and applies whichever offset is genuinely in force on the day.
Australian Central Time covers Adelaide and South Australia, on a half hour offset that also shifts for summer. Japan Standard Time covers Tokyo, Osaka and the whole of Japan. The identifiers behind them are Australia/Adelaide and Asia/Tokyo, which is what any calendar or scheduling system should be storing rather than a fixed number of hours.
Questions
- What is ACST in JST?
- ACST is 30 minutes ahead of JST. 9:00 am ACST is 8:30 am JST.
- How many hours ahead is JST of ACST?
- JST is 30 minutes behind ACST. That varies across the year, between 30 minutes and 1 hour 30 minutes.
- What time is it in Japan right now?
- 11:43 pm JST on Friday, September 25, 2026.
- When can Australian Central and Japan meet during working hours?
- Between 10:00 am and 5:00 pm ACST, which is 9:30 am to 4:30 pm JST.
- Does this account for daylight saving?
- Yes. Every reading is computed from the IANA database for the actual date, so ACST and JST are the abbreviations genuinely in force today rather than a fixed assumption.
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