Seoul to Castro Valley time converter

Castro Valley is 16 hours behind Seoul. When it is 9:00 AM in Seoul, it is 5:00 PM (Tue, Oct 20) in Castro Valley.

Seoul KST

Wednesday, October 21, 2026

Castro Valley PDT

Tuesday, October 20, 2026

Seoul
South Korea
Wed, Oct 21
KSTUTC+9
Castro Valley
California, United States
Tue, Oct 20
PDTUTC-7-16h
Finding your time zone…
Shared working hours (9:00–18:00)

Seoul to Castro Valley conversion table

Every hour of today in Seoul and the matching time in Castro Valley. Light rows are typical working hours (9:00–18:00).

SeoulCastro Valley
12:00 AM8:00 AM−1 day
1:00 AM9:00 AM−1 day
2:00 AM10:00 AM−1 day
3:00 AM11:00 AM−1 day
4:00 AM12:00 PM−1 day
5:00 AM1:00 PM−1 day
6:00 AM2:00 PM−1 day
7:00 AM3:00 PM−1 day
8:00 AM4:00 PM−1 day
9:00 AM5:00 PM−1 day
10:00 AM6:00 PM−1 day
11:00 AM7:00 PM−1 day
12:00 PM8:00 PM−1 day
1:00 PM9:00 PM−1 day
2:00 PM10:00 PM−1 day
3:00 PM11:00 PM−1 day
4:00 PM12:00 AM
5:00 PM1:00 AM
6:00 PM2:00 AM
7:00 PM3:00 AM
8:00 PM4:00 AM
9:00 PM5:00 AM
10:00 PM6:00 AM
11:00 PM7:00 AM

Best time to call or meet

Both sides are at work from 9:00 AM – 10:00 AM in Seoul (5:00 PM – 6:00 PM in Castro Valley).

Daylight saving time and the difference

The difference changes during the year because Seoul and Castro Valley switch clocks on different dates:

  • Oct 21, 2026 – Nov 1, 2026: -16h
  • Nov 1, 2026 – Mar 14, 2027: -17h
  • Mar 14, 2027 – Oct 21, 2027: -16h

Distance

Seoul and Castro Valley are 9,057 km (5,628 miles) apart in a straight line.

More conversions

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Questions and answers

What is the time difference between Seoul and Castro Valley?

Castro Valley is 16 hours behind Seoul.

What time is it in Castro Valley when it is 9 AM in Seoul?

When it is 9:00 AM in Seoul, it is 5:00 PM (Tue, Oct 20) in Castro Valley.

When is the best time to call Castro Valley from Seoul?

Both sides are at work from 9:00 AM – 10:00 AM in Seoul (5:00 PM – 6:00 PM in Castro Valley).

Does the time difference between Seoul and Castro Valley change?

Yes, for part of the year, because daylight saving time starts and ends on different dates or applies on one side only.