Time Zone Converter

How time conversion works

The converter takes a specific date and time in one city — your source — and translates it into the equivalent moment in each destination city. The math accounts for daylight saving time automatically. If you set a date in March or November when clocks change for daylight saving, the destination times reflect whichever rules apply on that specific date.

Why some destinations show a different day

If your source time is late evening or early morning, destinations far away can land on a different calendar day. The converter highlights these in blue with a "next day" or "previous day" label. This is the single most common source of cross-timezone scheduling mistakes — sending a meeting invite for Wednesday 9 AM your time, only to find your colleague joined on Thursday morning their time. The day label makes the shift impossible to miss.

Common conversions

A few patterns come up repeatedly when working internationally:

• US East ↔ UK: 5 hours apart (4 during overlapping daylight saving periods). 9 AM New York is 2 PM London.
• UK ↔ India: 4.5 or 5.5 hours ahead. 9 AM London is 1:30 PM or 2:30 PM Mumbai.
• UK ↔ Tokyo: 8 or 9 hours ahead. 9 AM London is 5 PM or 6 PM Tokyo.
• US East ↔ Sydney: 14 to 16 hours ahead. Almost always next day in Australia.

Tips

• Use the "Now" button to reset the time to the current moment in your source city.
• Add multiple destinations if you're coordinating a group — the converter handles any number of cities.
• Saved automatically. Your source city and destination list are remembered in your browser between visits.

Common time-zone conversion mistakes

Most cross-time-zone scheduling errors trace back to a short list of predictable slip-ups:

• Forgetting the daylight-saving mismatch. Two regions can change their clocks on different dates, so the gap between them briefly shifts by an hour. A converter that applies the correct rule for the specific date avoids this; mental arithmetic usually doesn't.
• Rounding away the half hour. India, Nepal, and parts of Australia and Canada sit on 30- or 45-minute offsets. Treating them as whole hours puts every meeting 30 minutes off.
• Converting in the wrong direction. "New York is 5 hours behind London" is easy to flip under pressure. Setting an explicit source and destination removes the guesswork.
• Missing the day change. Late-evening and early-morning times often land on a different calendar day at the destination — the classic cause of a colleague joining a call a full 24 hours out.

A worked example

Suppose you want to invite a colleague in Tokyo to a call at 3:00 PM your time in New York. Set New York as the source, 3:00 PM as the time, and add Tokyo as a destination. The converter shows 4:00 AM in Tokyo — the next calendar day, flagged in blue. That's plainly unworkable, so you try 8:00 PM New York instead: now it reads 9:00 AM Tokyo, the same relative day, comfortably inside working hours. The whole check takes a few seconds, and crucially it surfaces the day-shift you'd never catch from "Tokyo is 13 or 14 hours ahead" alone. That day label is the single most valuable thing on the screen — it's the difference between a 9 AM meeting and an accidental one at 9 AM tomorrow.

The history of standardised time

Before railways, every town kept its own local solar time — noon was when the sun was highest overhead. A city 50 miles east was a few minutes ahead; one to the west, a few minutes behind. This worked fine when travel was slow enough that nobody cared about minutes.

Railways made it unworkable. Timetables listing departures in dozens of different local times caused confusion and collisions. In Britain, the Great Western Railway adopted a single "Railway Time" based on Greenwich in 1840; most other railways followed within a decade. By 1855 most of Britain had converged on Greenwich Mean Time. The global agreement came at the International Meridian Conference in Washington DC in 1884, where 25 nations settled on Greenwich as the universal zero-meridian. The system of 24 time zones, each one hour apart, followed. Today more than 400 distinct civil time offsets exist — including half-hour and quarter-hour variants — but they all trace back to that Greenwich anchor, expressed as hours (and sometimes minutes) ahead of or behind UTC, the modern atomic-clock successor to GMT.

Why daylight saving complicates every converter

Simple arithmetic — "add 5 hours" — works for fixed offsets. It breaks down around daylight saving time, which is why a converter that only knows UTC offsets is not the same as one that knows the rules for specific places on specific dates.

The complication runs in two directions. First, not all countries observe daylight saving at all — Japan, India, China, and most of the Middle East use fixed offsets year-round. A conversion between London and Mumbai that applies a flat "4 or 5 hours" will be wrong for half the year: the correct gap is 4 hours 30 minutes in summer and 5 hours 30 minutes in winter. Second, countries that do observe daylight saving rarely shift on the same date. The United States and Canada move their clocks on the second Sunday of March; most of Europe moves two weeks later. That two-week window is the most common source of off-by-one-hour scheduling mistakes in transatlantic business — a US–UK meeting that runs comfortably at 3 PM New York / 8 PM London for most of the year briefly becomes 3 PM New York / 7 PM London in mid-March before the UK catches up.

Australia adds another layer: its seasons are reversed, so daylight saving runs from October to April rather than March to November. A London–Sydney conversion that works in June looks completely different in November. This converter handles all of this by looking up the full rules for each specific city on the date you enter — not just applying a flat offset — which is why the date field matters as much as the time field.

Common city-pair guides

For quick reference on specific city-pair time differences (including the daylight saving transition weeks that catch most people out):

• Time difference between London and New York — 5 hours, transatlantic
• Time difference between London and Paris — always 1 hour, never changes
• Time difference between London and Dubai — 3 or 4 hours, Dubai has no DST
• Time difference between London and Tokyo — 8 or 9 hours, asymmetric DST
• Time difference between London and Sydney — 9 to 11 hours, opposite-hemisphere DST
• Time difference between New York and Los Angeles — 3 hours, US transcontinental
• Time difference between London and Mumbai — 4.5 or 5.5 hours, India's unique half-hour offset
• Time difference between New York and Tokyo — 13 or 14 hours, almost always different calendar days

Not sure what UTC offsets mean? Our plain-English UTC guide explains the offset system and how time zones are calculated from it.

Zone conversion guides

Quick-reference guides for the most-searched time zone conversions, each with a full table and daylight-saving notes:

• Convert EST to PST — Eastern to Pacific, 3 hours
• Convert PST to EST — Pacific to Eastern, 3 hours
• Convert EST to CST — Eastern to Central, 1 hour
• Convert CST to EST — Central to Eastern, 1 hour
• Convert UTC to EST — the universal reference to US Eastern
• Convert GMT to IST — GMT to India, 5½ hours (half-hour offset)
• Convert IST to EST — India to US Eastern (10½ / 9½ hours)
• Convert CET to EST — Central Europe to US Eastern, 6 hours

Frequently asked questions