Standard year-round offset: Tokyo is 6 hours ahead of Riyadh in both winter (AST UTC+3 → JST UTC+9) and summer (AST UTC+3 → JST UTC+9). When it is 9:00 AM in Riyadh, it is 3:00 PM JST in Tokyo. Best meeting window: 9:00 AM – 11:00 AM AST in Riyadh (3:00 PM – 5:00 PM JST in Tokyo — Golden 9–5 Overlap).
At the standard 6 hours offset (AST to JST), Riyadh and Tokyo share 2 hours/day of simultaneous 9:00 AM – 5:00 PM business hours: 9:00 AM – 11:00 AM AST in Riyadh equals 3:00 PM – 5:00 PM JST in Tokyo.
Both Riyadh (AST) and Tokyo (JST) are simultaneously inside 9:00 AM – 5:00 PM core working hours (2h/day year-round).
Covers 16 hours/day when either Riyadh (AST) or Tokyo (JST) is outside 7:00 AM – 9:00 PM local time.
Because Tokyo is 6 hours ahead of Riyadh, Tokyo crosses midnight into the next calendar day (+1 day) at 6:00 PM AST in Riyadh. From 12:00 AM to 6:00 PM AST in Riyadh, both locations are on the same weekday; from 6:00 PM AST to 11:59 PM in Riyadh, Sun–Thu in Riyadh maps to Mon–Fri in Tokyo.
Weekend & Workday Alignment: Weekend collision (Riyadh Fri–Sat vs. Tokyo Sat–Sun): Sunday is a workday in Riyadh (Saudi Arabia), but until 6:00 PM AST it is still Sunday in Tokyo (Tokyo's weekend), and Friday in Tokyo falls on Riyadh's Friday–Saturday weekend. Shared non-weekend workdays are Monday through Thursday.
Geographically, Riyadh (Saudi Arabia, 24.71°N, 46.68°E, IATA: RUH) and Tokyo (Japan, 35.68°N, 139.65°E, IATA: HND/NRT) are separated by a great-circle distance of 8,689 km (5,399 miles, approximately 10.5h non-stop flight). By longitude, true solar time in Tokyo is 6 hours and 12 minutes ahead of Riyadh (a 12-minute divergence from the 6 hours standard civil clock offset): Riyadh (24.71°N, 46.68°E) sits 1.68° east of the 45.0°E AST reference meridian, so mean solar noon occurs at 11:53 AM AST year-round, while 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.
For Riyadh → Tokyo: Arabia Standard Time (AST, UTC+3) is observed year-round across Saudi Arabia, Qatar, Kuwait, Bahrain, and Iraq with no Daylight Saving Time. Note: In North America and the Caribbean, AST denotes Atlantic Standard Time (UTC-4 in winter; ADT UTC-3 in summer).
| Abbreviation Meaning | UTC Offset | IANA Zone | Major Cities & Regions |
|---|---|---|---|
| Arabia Standard Time (Middle East) Primary Here | UTC+3 (year-round, no DST) | Asia/Riyadh | Active on Riyadh → Tokyo: Riyadh, Jeddah (Saudi Arabia), Doha (Qatar), Kuwait City, Baghdad, Manama |
| Atlantic Standard Time (North America & Caribbean) | UTC-4 (ADT UTC-3 in summer; UTC-4 year-round in Puerto Rico) | America/Halifax | Not used for Riyadh → Tokyo: Halifax (Nova Scotia), San Juan (Puerto Rico), Bermuda, Barbados |
For Riyadh → Tokyo: Saudi Arabia officially observes a Sunday–Thursday workweek (Friday–Saturday weekend), though schedules at some multinational private-sector offices vary. When coordinating with Monday–Friday teams in Europe or North America, the standard overlapping workweek is Monday through Thursday (4 days/week).
Computed Friday & Sunday 9–5 Overlap: 0 hours (None). Friday is part of the weekend in Riyadh (Saudi Arabia), and Sunday is part of the weekend in Tokyo (Japan).
Standard shared workdays (Riyadh ↔ Tokyo): Monday through Thursday (4 days/week — 2h/day in winter AST, 2h/day in summer AST).
| Riyadh Time | Tokyo (Standard (AST → JST)) | Day Shift | Call Status |
|---|---|---|---|
| 9:00 AM AST (Morning Start) | 3:00 PM JST | Same day | Working Overlap (9–5) |
| 12:00 PM AST (Midday / Noon) | 6:00 PM JST | Same day | Shoulder Hours |
| 3:00 PM AST (Afternoon) | 9:00 PM JST | Same day | Late evening / night |
| 6:00 PM AST (Evening Wrap-up) | 12:00 AM JST (+1 day) | +1 day | Overnight / Rest |
| Riyadh (AST) | Tokyo (Standard (AST → JST)) | Day (Tokyo) | Availability (Riyadh ↔ Tokyo) |
|---|---|---|---|
| 12:00 AM AST in Riyadh | 6:00 AM JST in Tokyo | Same day | Riyadh–Tokyo Overnight |
| 1:00 AM AST in Riyadh | 7:00 AM JST in Tokyo | Same day | Riyadh–Tokyo Overnight |
| 2:00 AM AST in Riyadh | 8:00 AM JST in Tokyo | Same day | Riyadh–Tokyo Overnight |
| 3:00 AM AST in Riyadh | 9:00 AM JST in Tokyo | Same day | Riyadh–Tokyo Overnight |
| 4:00 AM AST in Riyadh | 10:00 AM JST in Tokyo | Same day | Riyadh–Tokyo Overnight |
| 5:00 AM AST in Riyadh | 11:00 AM JST in Tokyo | Same day | Riyadh–Tokyo Overnight |
| 6:00 AM AST in Riyadh | 12:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Overnight |
| 7:00 AM AST in Riyadh | 1:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Shoulder |
| 8:00 AM AST in Riyadh | 2:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Shoulder |
| 9:00 AM AST in Riyadh | 3:00 PM JST in Tokyo | Same day | Riyadh–Tokyo 9–5 |
| 10:00 AM AST in Riyadh | 4:00 PM JST in Tokyo | Same day | Riyadh–Tokyo 9–5 |
| 11:00 AM AST in Riyadh | 5:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Shoulder |
| 12:00 PM AST in Riyadh | 6:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Shoulder |
| 1:00 PM AST in Riyadh | 7:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Shoulder |
| 2:00 PM AST in Riyadh | 8:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Shoulder |
| 3:00 PM AST in Riyadh | 9:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Late evening / night |
| 4:00 PM AST in Riyadh | 10:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Late evening / night |
| 5:00 PM AST in Riyadh | 11:00 PM JST in Tokyo | Same day | Riyadh–Tokyo Late evening / night |
| 6:00 PM AST in Riyadh | 12:00 AM JST in Tokyo | +1 day | Riyadh–Tokyo Overnight |
| 7:00 PM AST in Riyadh | 1:00 AM JST in Tokyo | +1 day | Riyadh–Tokyo Overnight |
| 8:00 PM AST in Riyadh | 2:00 AM JST in Tokyo | +1 day | Riyadh–Tokyo Overnight |
| 9:00 PM AST in Riyadh | 3:00 AM JST in Tokyo | +1 day | Riyadh–Tokyo Overnight |
| 10:00 PM AST in Riyadh | 4:00 AM JST in Tokyo | +1 day | Riyadh–Tokyo Overnight |
| 11:00 PM AST in Riyadh | 5:00 AM JST in Tokyo | +1 day | Riyadh–Tokyo Overnight |
Neither Riyadh (AST, UTC+3, Asia/Riyadh) nor Tokyo (JST, UTC+9, Asia/Tokyo) observes Daylight Saving Time. Across all 12 months, Tokyo remains 6 hours ahead of Riyadh.
No Daylight Saving Time observed. Remains on AST (UTC+3) year-round.
No Daylight Saving Time observed. Remains on JST (UTC+9) year-round.
The standard time difference is 6 hours (Tokyo ahead of Riyadh) in both winter (AST → JST) and summer (AST → JST).
No — at 4:00 PM AST in Riyadh, it is 10:00 PM JST (same day) in Tokyo, which is after the 9:00 PM evening cutoff. Schedule earlier during 9:00 AM – 11:00 AM AST (3:00 PM – 5:00 PM JST in Tokyo).
Aim for 9:00 AM – 11:00 AM AST in Riyadh, which is 3:00 PM – 5:00 PM JST in Tokyo (2h/day of 9–5 overlap). Avoid calling between 3:00 PM – 7:00 AM AST (+1 day) in Riyadh (9:00 PM – 1:00 PM JST (+1 day) in Tokyo), when at least one city is outside 7:00 AM – 9:00 PM.
Neither Riyadh (Asia/Riyadh) nor Tokyo (Asia/Tokyo) observes Daylight Saving Time, so the 6 hours offset never changes.
Because Riyadh officially operates on a Sunday–Thursday workweek (Friday–Saturday weekend) while Tokyo works Monday–Friday (Saturday–Sunday weekend), there is 0 hours of standard business overlap on Fridays and Sundays. Schedule recurring team calls Monday through Thursday (2h/day overlap in winter; 2h/day in summer).