Convert time across any two zones

The day ribbon

The two strips under the date show a full day in each zone, and the lit band on each strip is that zone's 9 AM to 5 PM. Where the two bands line up, both people are at work. Drag the handle along the ribbon and both clocks move together in 15-minute steps, so you can slide through the day and see exactly where one side runs into the evening.

For zones close together, like London and Berlin, the bands overlap for most of the day. For zones far apart, like Los Angeles and Bangalore, they barely touch or don't meet at all, and the real decision is which side starts early or stays late.

Hour by hour

Further up the page there's a table with every hour of the chosen day side by side. Rows where both zones are inside working hours are shaded, and the line beside the table tells you how much of the day overlaps. Click any row to load that time into the converter.

On the day a zone changes its clocks, the table has 23 or 25 rows instead of 24, because that is how many hours the day really has there. It's a quick way to spot a clock change you didn't know was coming.

When there's no good slot

Once the gap passes about eight hours, no time is comfortable for everyone. Teams split between India and the US West Coast, or between Europe and Australia, usually end up with one side on an early call and the other on a late one. Taking turns is fairer than always asking the same office to stay up. The ribbon makes the trade visible: move the handle an hour either way and you can see who pays for it.

Daylight saving starts on different dates

The United States moves its clocks forward on the second Sunday in March and back on the first Sunday in November. The UK and the European Union switch on the last Sunday in March and the last Sunday in October. So for two or three weeks in March, and again for about a week around the start of November, New York is four hours behind London instead of the usual five. A meeting set up by "just subtracting five" lands an hour off in those weeks. You can see the shifting gap on the UK to EST and CET to EST pages.

The southern hemisphere runs the other way. Sydney and Melbourne go onto daylight time in early October and come off in early April, so the gap between Sydney and London moves between 9 and 11 hours over the year. Queensland, just to the north, doesn't change its clocks at all, which puts Brisbane on the same time as Sydney for half the year and an hour behind it for the other half.

Many countries don't use daylight saving at all. India, Japan, China, Singapore, the UAE and Pakistan stay on one offset all year. That is why the difference between India and New York moves between 9 hours 30 minutes and 10 hours 30 minutes even though India's clocks never change. The IST to EST page lists the exact dates.

The rules keep changing

Governments change their time zone rules more often than most people realise. Mexico dropped daylight saving for most of the country in 2022. Kazakhstan moved to a single time zone in 2024. Samoa jumped across the International Date Line at the end of 2011 and skipped 30 December entirely. A converter that stores one fixed offset per country gets cases like these wrong without anyone noticing.

This one uses the IANA time zone database, the same source used by phones, operating systems and most programming languages. Each zone is a named region such as America/New_York or Asia/Kolkata with a full history of its offsets. A date in the past gets the rules that applied then, and a date next year gets the rules that are scheduled. The conversion runs in your browser against its built-in copy of that database, so keeping your browser up to date keeps the rules current.

Abbreviations are ambiguous

CST can mean Central Standard Time in North America, China Standard Time or Cuba Standard Time. IST is used for India, Israel and Ireland. BST is British Summer Time to most people and Bangladesh Standard Time to others. People also say EST all year when they mean Eastern Time, even though New York is on EDT from March to November.

Search accepts abbreviations, but the zone the converter works with is always a named place. Pick Eastern Time and you get New York's rules, with EST in winter and EDT in summer, which is almost always what someone means when they write "EST". The full name and IANA identifier under each clock show exactly which zone you're looking at.

Not every offset is a whole hour

India is 5 hours 30 minutes ahead of UTC. Nepal is 5:45 ahead, Newfoundland is 3:30 behind, the Northern Territory of Australia is 9:30 ahead, and New Zealand's Chatham Islands run 12:45 ahead in their winter. Mental arithmetic tends to slip on these, especially when the answer also crosses midnight. The converter treats them like any other offset, as you can check on the UTC to IST page.

Clock changes create times that don't exist

When clocks spring forward in New York at 2:00 AM, they go straight to 3:00 AM, so a time like 2:30 AM never happens there on that date. If you type one, the converter says so and moves it to the first real time after the gap.

In autumn the opposite happens. The hour from 1:00 to 1:59 AM occurs twice, once on daylight time and once on standard time. The converter shows the first and tells you which abbreviation the second one uses, so you can decide which one you meant before sending an invite.