Time Zone Difference Calculator

Calculate the time difference between any two cities

Whether you are arranging an international call, tracking a global event, or simply curious about how many hours separate two cities, a time zone difference calculator gives you the answer instantly. Select two locations and the tool shows the current offset between them in hours, accounting for any daylight saving time currently in effect.

Why time zone differences change

The world is divided into approximately 40 distinct time zones, each defined by its offset from Coordinated Universal Time (UTC). Most offsets are whole hours, though some countries use half-hour or quarter-hour offsets — India is UTC+5:30, Nepal is UTC+5:45, and several Australian states use UTC+9:30 and UTC+10:30.

Daylight saving time (DST) complicates matters further. When one location observes DST and another does not, the effective offset between them changes. The United States and much of Europe both observe DST, but they change on different dates: the US changes in March and November while Europe changes in late March and October. During the period between these change dates, the US–Europe offset is one hour different from the rest of the year.

Practical uses for travellers

Before an international trip, knowing the time difference helps you prepare mentally for jet lag and plan your first few days. A traveller flying from New York to London gains 5 hours (or 6 hours during certain parts of the year depending on DST). Planning to call home during the trip requires knowing when it is a reasonable hour in both locations simultaneously.

Remote work and global teams

Remote teams increasingly span multiple time zones, making offset awareness essential. Many teams establish a core overlap window — the hours when most members are within normal working hours simultaneously. A 5-hour difference might still allow a 2-3 hour overlap window; a 12-hour difference requires someone to be at the fringe of their working day.

Scheduling tools, calendar applications, and project management platforms all handle time zones automatically, but understanding the underlying offset helps you reason about scheduling without relying on software.

Financial markets

Stock exchanges operate in specific local time zones: the New York Stock Exchange opens at 9:30 AM Eastern Time, the London Stock Exchange at 8:00 AM GMT, and the Tokyo Stock Exchange at 9:00 AM JST. Traders in other time zones need to know what these opening times mean locally, particularly for futures and foreign exchange markets that operate nearly continuously.

Aviation and logistics

Airlines publish timetables in local time at departure and arrival airports, which means a flight departing New York at 11 PM and arriving in London at 11 AM the next day takes 7 hours, not the apparent 12. Freight logistics similarly requires timezone awareness for customs documentation, perishable goods tracking, and just-in-time delivery windows.

The International Date Line

An extreme case of time zone differences is the International Date Line in the Pacific Ocean. Crossing it eastward moves you back one calendar day; crossing it westward moves you forward one day. Some island nations close to the date line have unusual offsets: Kiribati (UTC+14) is 26 hours ahead of American Samoa (UTC-12), even though they are geographically relatively close.

How to use the calculator

Select two locations from the dropdowns and the current offset between them appears immediately, already accounting for whichever daylight saving rules currently apply to each place. Because the calculation is based on today's date, revisit it during a different part of the year if a location observes daylight saving, since the offset between two specific cities can shift by an hour depending on the season even when neither city's own clock changes.

Scheduling a meeting across many time zones

Coordinating a single meeting time across three or more time zones is one of the most common practical uses of a time zone calculator. The general approach is to find the narrowest overlap of reasonable working hours across every participant's location, then check that overlap against each region's current daylight saving status, since a time that works in January might shift by an hour relative to a partner's schedule by July if the two locations change their clocks on different dates or one does not observe daylight saving at all. Teams that meet regularly across time zones often settle on a fixed UTC time for recurring meetings specifically to sidestep this seasonal drift, letting each participant's calendar software handle the local conversion automatically.

Half-hour and quarter-hour offsets

Most of the world's time zones sit at whole-hour offsets from UTC, which is why converting between most pairs of cities is simple hour arithmetic. A handful of regions break this pattern for historical or political reasons rather than any geographic necessity: India's UTC+5:30 offset was chosen at independence partly to sit at a single time roughly midway across the country's wide east-west extent, Nepal's UTC+5:45 offset is often cited as a deliberate choice to be distinct from neighbouring India's time, and Newfoundland in Canada uses UTC-3:30, a half-hour offset from the rest of Atlantic Canada. These fractional offsets are exactly why a reliable time zone tool needs to handle minutes as well as hours rather than assuming every offset is a round number.

Private and instant

The tool uses your browser's built-in Intl API to determine current UTC offsets, so results appear instantly and no data about the locations you check is ever sent anywhere, logged or shared.