“Is it too late to call my client overseas?” “What time is it in New York right now?” As international business and travel grow, so does the need to work out time differences. Daylight saving time (DST) makes this trickier: the offset between Tokyo and New York changes from 14 hours to 13 hours for part of the year, which confuses many people.
In this guide, we explain how time differences work and how to calculate them, in plain terms for beginners. You will learn about UTC, how daylight saving changes offsets, a handy table of major cities versus Japan, and a simple process for scheduling calls and meetings abroad.
What is a time difference? UTC and standard time
Time differences exist because regions use different standard times based on longitude. The reference point is UTC (Coordinated Universal Time). Every standard time is expressed as an offset from UTC, such as “UTC+9”.
| Region | Standard time | Difference from Japan |
|---|---|---|
| Japan | UTC+9 | Reference (0) |
| Singapore | UTC+8 | -1 hour |
| Dubai | UTC+4 | -5 hours |
| London | UTC±0 | -9 hours |
| New York | UTC-5 | -14 hours |
| Los Angeles | UTC-8 | -17 hours |
| Honolulu | UTC-10 | -19 hours |
Japan runs on UTC+9, nine hours ahead of Coordinated Universal Time. When it is noon in London (UTC±0), it is 9 PM in Japan.
Terminology: UTC is the successor to GMT (Greenwich Mean Time) and is now the global reference. Japan's standard time is also called JST.
How daylight saving time changes the offset
Daylight saving time (DST) moves clocks forward by one hour during summer to make better use of daylight. It is used mainly in Europe and North America.
| Region | DST | Typical period |
|---|---|---|
| Japan | Not observed | — |
| United States & Canada | Observed | 2nd Sunday in March - 1st Sunday in November |
| UK & Europe | Observed | Last Sunday in March - last Sunday in October |
| Australia (Sydney) | Observed | 1st Sunday in October - 1st Sunday in April |
During DST, the local time is one hour ahead of standard time. New York, for example, moves from EST (UTC-5) to EDT (UTC-4), so its difference from Japan changes from 14 hours to 13 hours.
Heads up: DST start and end dates change every year and differ by region. The southern hemisphere is also seasonally opposite, so when it is summer in Japan, Sydney is on standard time. Always check the other city's actual local time on the day.
Time difference table: Japan vs major cities
Here are the offsets from Japan (UTC+9). Cities that observe DST show both standard and daylight saving values.
| City | Standard time | During DST |
|---|---|---|
| Singapore | -1 hour | -1 hour (none) |
| Dubai | -5 hours | -5 hours (none) |
| Moscow | -6 hours | -6 hours (none) |
| Paris | -8 hours | -7 hours |
| London | -9 hours | -8 hours |
| New York | -14 hours | -13 hours |
| Los Angeles | -17 hours | -16 hours |
| Honolulu | -19 hours | -19 hours (none) |
| Sydney | +1 hour | +2 hours |
Quick mental math: subtract the offset from Japan time to get the other city's local time. For example, 9 PM in Tokyo minus New York's 14 hours (standard time) is 7 AM the previous day.
How to schedule calls and meetings abroad
When scheduling with overseas teammates, aim for the other side’s working hours (roughly 9 AM-5 PM local time).
Check the other city's current time
Use a timezone converter or world clock to see what time it is there right now. Remember that DST shifts the offset by one hour.
Aim for their working hours
Find a slot that falls within the other side's 9 AM-5 PM. For New York in standard time, 9 AM local is 11 PM in Tokyo, so Japanese evenings to late night are the candidates.
Share both times in the invitation
Write both times, such as "11 PM JST (9 AM EST)", plus the date, to avoid confusion.
As a concrete example, consider a meeting between Tokyo and New York:
- 9 PM in Tokyo is 7 AM in New York (standard time) — before their workday, so avoid.
- 10 PM in Tokyo is 8 AM in New York — close to their start.
- 11 PM in Tokyo is 9 AM in New York — this overlaps the start of their workday, a good slot for a meeting.
Japan-US meetings therefore often land in the Japanese evening to late night. During DST the offset shrinks by one hour, so 11 PM in Tokyo becomes 10 AM in New York.
Things to keep in mind
1. DST transition dates
US daylight saving changes in March and November; Europe changes in March and October. In the week around a transition, the offset depends on the exact date, so check day by day for longer schedules.
2. The date can differ
With a large offset, Japan and the other city may be on different dates. When it is Monday morning in Japan, it can still be Sunday night in New York. Always include the date in invitations.
3. Checking the local time directly is most reliable
Rather than memorizing offsets, look up the other city’s current time directly with a tool. This avoids calculation mistakes and DST oversights.
How to use the Tools Hub timezone converter & world clock
A free browser-based tool removes the need for mental math. The Tools Hub timezone converter shows current times and offsets in real time, with daylight saving handled automatically.
How to use it (three steps)
Pick your cities
Start with the defaults (Tokyo, New York, London, Los Angeles, Sydney) and add any other city you need.
Check the time and offset
The current time in each city and the offset from Tokyo update in real time. Daylight saving is applied automatically.
Use it to plan
Find a slot that overlaps the other side's working hours and schedule your call or meeting.
The tool from this guide
Timezone Converter & World Clock
Free, no sign-up required, and everything runs in your browser.
Summary
- Time differences come from each region’s standard time, expressed as an offset from UTC; Japan is UTC+9
- Daylight saving changes the offset by one hour; Japan does not observe DST
- Subtract the offset from Japan time to get the other city’s local time
- Schedule calls within the other side’s working hours and include both times and the date
- Watch out for DST transition dates and date differences across the date line
- When accuracy matters, check the other city’s local time directly with a tool
Once you understand “UTC offsets” and “daylight saving,” time differences are easy. Before scheduling your next international call or trip, check the current time with a tool.
FAQ
How do I calculate a time difference?
Subtract the offset from Japan time: “Japan time - offset = the other city’s local time.” For example, 9 PM in Tokyo minus New York’s 14 hours (standard time) is 7 AM the previous day.
Does Japan observe daylight saving time?
No. Japan does not observe DST. The US, Canada, parts of Europe and Australia do, and clocks move forward by one hour during their DST periods.
What is the time difference between Tokyo and New York?
14 hours in standard time (Tokyo is ahead). During US daylight saving it is 13 hours. For London, it is 9 hours in standard time and 8 hours during DST.
Any tips for scheduling calls with people overseas?
Aim for the other side’s working hours (roughly 9 AM-5 PM local). Japan-US calls often land in the Japanese evening to late night. Write both times and the date in the invitation to avoid confusion.
