Dublin is 9 hours behind Tokyo in winter (JST UTC+9 → GMT UTC+0) and 8 hours behind in summer (JST UTC+9 → IST UTC+1). A 9:00 AM start in Tokyo is 12:00 AM GMT in winter and 1:00 AM IST in summer in Dublin. Best meeting window — Winter (JST): 6:00 PM – 9:00 PM JST (9:00 AM – 12:00 PM GMT); Summer (JST): 4:30 PM – 7:30 PM JST (8:30 AM – 11:30 AM IST).
With a 9 hours gap in Winter (JST) (JST → GMT) and a 8 hours gap in Summer (JST) (JST → IST), Tokyo and Dublin have 0 hours of simultaneous 9:00 AM – 5:00 PM business hours in either season. Meetings use morning and early-evening shoulder windows within 7:00 AM – 9:00 PM local time.
Optimal Tokyo–Dublin shoulder bridge for Winter (JST) (9 hours gap) and Summer (JST) (8 hours gap), ending at or before 9:00 PM local time.
Covers every hour where Tokyo or Dublin is outside 7:00 AM – 9:00 PM local time (19h/day in Winter (JST); 18h/day in Summer (JST)).
| Tokyo Time | Dublin (Winter (JST → GMT)) | Day Shift | Dublin (Summer (JST → IST)) | Call Status |
|---|---|---|---|---|
| 9:00 AM JST (Morning Start) | 12:00 AM GMT | Same day | 1:00 AM IST | Overnight / Rest |
| 12:00 PM JST (Midday / Noon) | 3:00 AM GMT | Same day | 4:00 AM IST | Overnight / Rest |
| 3:00 PM JST (Afternoon) | 6:00 AM GMT | Same day | 7:00 AM IST | Overnight / Rest |
| 6:00 PM JST (Evening Wrap-up) | 9:00 AM GMT | Same day | 10:00 AM IST | Shoulder Hours |
| Tokyo (JST) | Dublin (Winter (JST → GMT)) | Day (Dublin) | Dublin (Summer (JST → IST)) | Availability (Tokyo ↔ Dublin) |
|---|---|---|---|---|
| 12:00 AM JST in Tokyo | 3:00 PM GMT in Dublin | -1 day | 4:00 PM IST (-1 day) | Tokyo–Dublin Overnight |
| 1:00 AM JST in Tokyo | 4:00 PM GMT in Dublin | -1 day | 5:00 PM IST (-1 day) | Tokyo–Dublin Overnight |
| 2:00 AM JST in Tokyo | 5:00 PM GMT in Dublin | -1 day | 6:00 PM IST (-1 day) | Tokyo–Dublin Overnight |
| 3:00 AM JST in Tokyo | 6:00 PM GMT in Dublin | -1 day | 7:00 PM IST (-1 day) | Tokyo–Dublin Overnight |
| 4:00 AM JST in Tokyo | 7:00 PM GMT in Dublin | -1 day | 8:00 PM IST (-1 day) | Tokyo–Dublin Overnight |
| 5:00 AM JST in Tokyo | 8:00 PM GMT in Dublin | -1 day | 9:00 PM IST (-1 day) | Tokyo–Dublin Overnight |
| 6:00 AM JST in Tokyo | 9:00 PM GMT in Dublin | -1 day | 10:00 PM IST (-1 day) | Tokyo–Dublin Overnight |
| 7:00 AM JST in Tokyo | 10:00 PM GMT in Dublin | -1 day | 11:00 PM IST (-1 day) | Tokyo–Dublin Late evening / night |
| 8:00 AM JST in Tokyo | 11:00 PM GMT in Dublin | -1 day | 12:00 AM IST | Tokyo–Dublin Late evening / night |
| 9:00 AM JST in Tokyo | 12:00 AM GMT in Dublin | Same day | 1:00 AM IST | Tokyo–Dublin Overnight |
| 10:00 AM JST in Tokyo | 1:00 AM GMT in Dublin | Same day | 2:00 AM IST | Tokyo–Dublin Overnight |
| 11:00 AM JST in Tokyo | 2:00 AM GMT in Dublin | Same day | 3:00 AM IST | Tokyo–Dublin Overnight |
| 12:00 PM JST in Tokyo | 3:00 AM GMT in Dublin | Same day | 4:00 AM IST | Tokyo–Dublin Overnight |
| 1:00 PM JST in Tokyo | 4:00 AM GMT in Dublin | Same day | 5:00 AM IST | Tokyo–Dublin Overnight |
| 2:00 PM JST in Tokyo | 5:00 AM GMT in Dublin | Same day | 6:00 AM IST | Tokyo–Dublin Overnight |
| 3:00 PM JST in Tokyo | 6:00 AM GMT in Dublin | Same day | 7:00 AM IST | Tokyo–Dublin Overnight |
| 4:00 PM JST in Tokyo | 7:00 AM GMT in Dublin | Same day | 8:00 AM IST | Tokyo–Dublin Shoulder |
| 5:00 PM JST in Tokyo | 8:00 AM GMT in Dublin | Same day | 9:00 AM IST | Tokyo–Dublin Shoulder |
| 6:00 PM JST in Tokyo | 9:00 AM GMT in Dublin | Same day | 10:00 AM IST | Tokyo–Dublin Shoulder |
| 7:00 PM JST in Tokyo | 10:00 AM GMT in Dublin | Same day | 11:00 AM IST | Tokyo–Dublin Shoulder |
| 8:00 PM JST in Tokyo | 11:00 AM GMT in Dublin | Same day | 12:00 PM IST | Tokyo–Dublin Shoulder |
| 9:00 PM JST in Tokyo | 12:00 PM GMT in Dublin | Same day | 1:00 PM IST | Tokyo–Dublin Late evening / night |
| 10:00 PM JST in Tokyo | 1:00 PM GMT in Dublin | Same day | 2:00 PM IST | Tokyo–Dublin Late evening / night |
| 11:00 PM JST in Tokyo | 2:00 PM GMT in Dublin | Same day | 3:00 PM IST | Tokyo–Dublin Late evening / night |
Between Tokyo (Japan, Asia/Tokyo) and Dublin (Ireland, Europe/Dublin), the seasonal offset shifts by 1 hour. In winter standard time (JST vs. GMT), Dublin (UTC+0) is 9 hours behind Tokyo (UTC+9). In summer (JST vs. IST), Dublin (UTC+1) is 8 hours behind Tokyo (UTC+9).
No Daylight Saving Time observed. Remains on JST (UTC+9) year-round.
| Date Window | Duration | Active Zones | Time Difference | Regime |
|---|---|---|---|---|
| Since Oct 25, 2026 | 154 days | JST (UTC+9) → GMT (UTC+0) | 9 hours | Standard Alignment (Active Now) |
| Mar 28, 2027 – Oct 31, 2027 | 217 days | JST (UTC+9) → IST (UTC+1) | 8 hours | Standard Alignment |
| Oct 31, 2027 – Nov 3, 2027 | 3 days | JST (UTC+9) → GMT (UTC+0) | 9 hours | Standard Alignment |
Because Dublin is 9 hours behind Tokyo in winter and 8 hours behind in summer, Dublin remains on the previous calendar day (-1 day) from 12:00 AM until 9:00 AM JST in winter (8:00 AM JST in summer) in Tokyo. During those hours, Mon–Fri in Tokyo maps to Sun–Thu in Dublin (and Tue–Sat in Tokyo maps to Mon–Fri in Dublin). After 9:00 AM JST (8:00 AM JST in summer), both locations share the same weekday.
Weekend & Workday Alignment: Monday morning in Tokyo (before 9:00 AM JST / 8:00 AM JST in summer) lands on Sunday in Dublin—which is Dublin's weekend (Sat–Sun). Likewise, Friday afternoon/evening in Dublin corresponds to Saturday morning in Tokyo (Tokyo's Sat–Sun weekend). Morning calls in Tokyo should be scheduled Tuesday–Friday in Tokyo (which is Monday–Thursday afternoon/evening in Dublin).
Geographically, Tokyo (Japan, 35.68°N, 139.65°E, IATA: HND/NRT) and Dublin (Ireland, 53.35°N, 6.26°W, IATA: DUB) are separated by a great-circle distance of 9,585 km (5,956 miles, approximately 12h non-stop flight). By longitude, true solar time in Dublin is 9 hours and 44 minutes behind Tokyo (a 44-minute divergence from the 9 hours standard civil clock offset): Tokyo (35.68°N, 139.65°E) sits 4.65° east of the 135.0°E JST reference meridian, so mean solar noon occurs at 11:41 AM JST year-round, while Dublin (53.35°N, 6.26°W) sits 6.26° west of the 0.0°E GMT reference meridian, so mean solar noon occurs at 12:25 PM GMT in winter and 1:25 PM IST in summer.
For Tokyo → Dublin: India Standard Time (IST, UTC+5:30) is a single national half-hour offset observed year-round across all of India (IANA zone Asia/Kolkata) with no Daylight Saving Time. Note: Neighboring Sri Lanka shares the same UTC+5:30 offset year-round under its own IANA timezone (Asia/Colombo, Sri Lanka Standard Time / SLST).
| Abbreviation Meaning | UTC Offset | IANA Zone | Major Cities & Regions |
|---|---|---|---|
| India Standard Time Primary Here | UTC+5:30 (year-round, no DST) | Asia/Kolkata | Not used for Tokyo → Dublin: Mumbai, New Delhi, Bengaluru, Hyderabad, Chennai, Pune (India) |
| Irish Standard Time Primary Here | UTC+1 (summer only; GMT UTC+0 in winter) | Europe/Dublin | Active on Tokyo → Dublin: Dublin, Cork, Galway (Ireland) |
| Israel Standard Time | UTC+2 (IDT UTC+3 in summer) | Asia/Jerusalem | Not used for Tokyo → Dublin: Tel Aviv, Jerusalem (Israel) |
In winter (standard time), Dublin (GMT, UTC+0) is 9 hours behind Tokyo (JST, UTC+9). In summer (daylight saving time), Dublin (IST, UTC+1) is 8 hours behind Tokyo (JST, UTC+9).
4:00 PM in Tokyo corresponds to 7:00 AM GMT (same day) in winter and 8:00 AM IST (same day) in summer in Dublin, placing it inside waking hours (7:00 AM – 9:00 PM) in both cities.
In winter (JST), the best window is 6:00 PM – 9:00 PM JST in Tokyo (9:00 AM – 12:00 PM GMT in Dublin). In summer (JST), use 4:30 PM – 7:30 PM JST in Tokyo (8:30 AM – 11:30 AM IST in Dublin). Avoid hours outside 7:00 AM – 9:00 PM local time (9:00 PM – 4:00 PM JST (+1 day) in winter; 9:00 PM – 3:00 PM JST (+1 day) in summer).
Tokyo: No DST (JST year-round). Dublin: Sun, Mar 28, 2027 (GMT → IST, new gap: 8 hours (IST UTC+1 vs JST UTC+9)).
In winter (JST), 9:00 AM Tokyo is 12:00 AM GMT and 12:00 PM is 3:00 AM GMT in Dublin. In summer (JST), 9:00 AM is 1:00 AM IST and 12:00 PM is 4:00 AM IST.