JST to AST Time Zone Converter — Time Difference Between Tokyo and San Juan
Drag the slider or click the time display to type a specific hour and instantly convert JST to AST. The time difference between Tokyo and San Juan is 13 hours — San Juan (AST) is behind Tokyo (JST) (UTC+9:00 vs UTC-4:00); for example, 9:00 AM JST = 8:00 PM (previous day) AST; to convert, subtract 13 hours. Use this JST to AST time zone converter to check the live current time in both cities, browse the 24-hour JST to AST conversion table, plan international meetings, find the best overlap hours, and account for daylight saving time changes automatically.
JST
Japan Standard Time
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AST
Atlantic Standard Time
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JST to AST Time Zone Difference — Hour-by-Hour Conversion Table
Scan each row to convert any JST time to AST and find the exact time difference between Tokyo and San Juan hour by hour. Amber-highlighted rows mark standard daytime business hours, making it easy to spot overlapping work windows for scheduling international meetings or remote team calls. Tap the arrows to jump between days, click "Today" to reset, and all daylight saving time transitions are handled automatically.
| JST (Tokyo) | AST (San Juan) |
|---|
What Time Is It Now in Tokyo?
Live current local time in Tokyo, Japan — JST (UTC+9:00). Updates every second.
What Time Is It Now in San Juan?
Live current local time in San Juan, Puerto Rico — AST (UTC-4:00). Updates every second.
JST to AST Quick Reference
Common business hours in Tokyo converted to San Juan local time — handy for scheduling video calls, client meetings, and international conference calls.
JST & AST Meeting Planner — Best Overlapping Hours
Use the color-coded conversion table above to find overlapping business hours between Tokyo and San Juan. Amber rows mark standard daytime work hours (8 AM–6 PM local time) — pick a slot that falls in amber on both sides for a meeting time that works for everyone. Since JST (UTC+9:00) is 13 hours behind AST (UTC-4:00), this time zone meeting planner is ideal for scheduling international calls, remote team standups, and cross-border project syncs.
Why Trust This Tokyo to San Juan Time Zone Converter?
ConvertFlash uses the IANA Time Zone Database — the same authoritative source that powers your phone, browser, and every major operating system — so every Tokyo to San Juan conversion handles daylight saving time transitions, half-hour UTC offsets, and historical time zone changes automatically. The live world clock updates every second, and the hour-by-hour conversion table regenerates correctly for any past or future date you select, making it reliable for both real-time checks and advance international scheduling.
JST — Japan Standard Time
Tokyo, Japan — UTC offset UTC+9:00
- Abbreviation
- JST
- UTC Offset
- UTC+9:00
- City
- Tokyo
- Country
- Japan
AST — Atlantic Standard Time
San Juan, Puerto Rico — UTC offset UTC-4:00
- Abbreviation
- AST
- UTC Offset
- UTC-4:00
- City
- San Juan
- Country
- Puerto Rico