Time Difference Calculator – Compare Two Cities or Time Zones

Quickly check the time difference between any two major cities around the world. See who is ahead or behind, get current local times, and generate a clear summary you can copy or share.

Perfect before calling abroad

Use this time difference calculator together with our International Dialing tool to pick a suitable time and dial correctly.

Location A (reference)

Time difference will be shown as “Location B is ahead/behind Location A”.

Location B (comparison)

We use official IANA time zones (e.g., Europe/London, Asia/Tokyo) so DST changes are handled automatically.

Convert a specific time from A to B

For simplicity we use the same current time zone rules (including DST). Around daylight-saving switch dates results may differ slightly from historical times.

Result – time difference

Current local times

Location A

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Location B

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Time difference

Select two locations and click “Calculate difference (now)”.

For example: “When it is 09:00 in London, it is 18:00 in Tokyo (Tokyo is 9 hours ahead of London).”

Specific time conversion

Enter a date & time for Location A and click “Convert A → B”.

All calculations are based on your browser’s current date/time and official IANA time zones. For airline schedules or critical meetings, always double-check with an official source.

How the time difference calculator works

This time difference calculator uses the current date and official time zone rules for each selected city. Behind the scenes, your browser applies IANA time zones (for example Europe/London and Asia/Tokyo) to figure out the offset from UTC, including daylight saving time (DST) if applicable.

When you select two locations and click “Calculate difference (now)”, the tool:

Reads the current moment from your device clock.
Converts this moment to the local time in Location A.
Converts the same moment to the local time in Location B.
Computes the difference (in minutes) between the two local times.
Formats a human-readable sentence like “Tokyo is 9 hours ahead of London”.

Example: time difference between London and Tokyo

Suppose you choose London, United Kingdom as Location A and Tokyo, Japan as Location B and run the calculator:

London is in the time zone Europe/London.
Tokyo is in the time zone Asia/Tokyo.
Outside of daylight saving time, London is UTC+0 and Tokyo is UTC+9.
The time difference is therefore 9 hours.

The tool will show something like:
When it is 09:00 on 2025-12-09 in London, United Kingdom, it is 18:00 on 2025-12-09 in Tokyo, Japan (Tokyo is 9 hours ahead of London).

Why daylight saving time (DST) matters

Many countries in Europe and North America use daylight saving time, moving clocks forward in spring and back in autumn. Because of this, the time difference between two cities can change during the year. For example:

London vs. New York is usually 5 hours (London ahead).
During some weeks around the DST switch, the difference can temporarily be 4 or 6 hours.

Our calculator always uses the current time zone rules. If you need historical time differences for a date far in the past, check with an official world clock or time zone database.

Good use cases for a time difference calculator

People use time difference tools in many real-world scenarios:

Scheduling online meetings across continents (e.g., USA – Germany – Japan).
Choosing a time to call friends or family abroad without waking them up at night.
Checking how trading hours in London, New York, and Hong Kong overlap.
Planning international flights or layovers around local arrival times.

Combine time difference with world time & dialing tools

This calculator is part of the broader toolset on CountryCode.online. For a complete workflow you can:

Use the World Time tool to quickly see the current time in multiple cities at once.
Use this Time Difference Calculator to find a fair meeting time across all locations.
Use the International Dialing tool to compose the correct phone number format when calling abroad.

FAQ about time differences and time zones

Why does the time difference between two cities change during the year? ▶

The time difference can change because of daylight saving time (DST). Some countries move their clocks forward in spring and back in autumn, while others stay on standard time all year. If one city observes DST and the other does not, the offset between them will vary across the year.

Does this calculator handle daylight saving time automatically? ▶

Yes. The tool relies on your browser’s built-in support for IANA time zones such as America/New_York or Europe/Berlin. These include the latest DST rules. However, some very old historical changes or future law changes may not yet be reflected, so critical applications should always be double-checked.

Can I use this to convert a meeting time next month or next year? ▶

You can enter a specific date and time for Location A, and the calculator will apply the current time zone rules to estimate the time in Location B. This usually works well for near-future meetings, but if your country introduces new DST rules or changes its time zone, the result may no longer be accurate. For long-term planning, verify the time again closer to the date.

How is this different from a world clock? ▶

A world clock simply shows the current time in different cities. This time difference calculator goes further: it compares two specific locations, shows who is ahead or behind, calculates the exact offset in hours and minutes, and lets you convert a custom time from one location to the other with a human-readable explanation.