Timezone Converter
Convert times between 20+ world timezones instantly. Quick buttons for popular routes like London to New York, London to Tokyo
Conversion Result
GMT (London)
April 30, 2026 at 01:00:00 PM
EST (New York)
April 30, 2026 at 08:00:00 AM
Timezone Offset
-5 hours difference
Quick Conversions
How to Convert Times Between Timezones
Pick a source timezone (where the time is now), a target timezone (where you want to know the time), enter the time and date, and the converter does the offset arithmetic. Quick-jump buttons handle the most common business pairings: London to New York, London to Tokyo, Singapore to London, Sydney to New York. The calculation uses the browser's Intl.DateTimeFormat API, so the result reflects the actual local time including any current daylight saving offset.
All times are anchored to UTC (Coordinated Universal Time) under the hood. UTC has no daylight saving and runs at the same speed everywhere on Earth. Each city or country has an offset from UTC: London is UTC+0 in winter and UTC+1 in summer, New York is UTC-5 in winter and UTC-4 in summer, Tokyo is permanently UTC+9. The converter looks up the offset for both timezones on the date you specify, then shifts the time accordingly.
Why Time Differences Aren't Constant
London to New York is usually 5 hours, but for two weeks each year it's 4 hours. This is because the UK and US don't change clocks on the same day. The UK switches to British Summer Time on the last Sunday in March and back to GMT on the last Sunday in October. The US switches on the second Sunday in March and the first Sunday in November. Between those mismatched dates the time difference shifts by an hour.
Some places skip the dance entirely. Iceland never changes clocks. Most of Asia (Tokyo, Singapore, Hong Kong, Beijing) stays on a fixed offset year-round. India is permanently UTC+5:30 and never observes daylight saving. This is why a 'time difference' question doesn't have a single answer until you specify the date.
Time Difference From London During Different Months
| City | Winter (Nov-Mar) | Summer (Apr-Oct) |
|---|---|---|
| New York | -5 hours | -5 hours (briefly -4 in late Mar/early Nov) |
| Los Angeles | -8 hours | -8 hours (briefly -7) |
| Tokyo | +9 hours | +8 hours |
| Sydney | +11 hours | +9 or +10 hours (Australia changes opposite) |
| Dubai | +4 hours | +3 hours |
| Singapore | +8 hours | +7 hours |
| Mumbai | +5:30 hours | +4:30 hours |
Practical Uses for the Converter
Scheduling international meetings is the obvious one. Less obvious: working out when a flight lands in local time, checking when a US store opens for an online drop, knowing whether it's a reasonable hour to message family abroad, or converting a webinar start time published in 'Eastern Time' into the time on your wall clock. For travel planning specifically, the [Distance Calculator](/distance-calculator) shows time-zone offset alongside flight time and great-circle distance.
When co-ordinating across multiple zones, the ISO 8601 format (YYYY-MM-DD HH:MM:SS) plus an offset like '+00:00' is the safest way to write a time without ambiguity. Saying '3pm' is easy to misunderstand; '15:00 UTC+0' is not.
Frequently Asked Questions
Does the converter handle daylight saving time?
Yes, automatically. The converter looks up each timezone's actual offset on the specific date you enter. So if you convert a 3pm London time on a date in July, it knows London is on BST (+1) and converts accordingly. If you pick a date in January, it uses GMT (+0). You don't need to think about whether the clocks have changed.
What's the difference between UTC and GMT?
In casual use, none, both refer to the time at zero longitude. Strictly, UTC is the modern atomic-clock standard and GMT is the older astronomical version, but they're synchronised to within fractions of a second. The UK uses GMT in winter and switches to BST (British Summer Time, UTC+1) in summer. UTC is used by aviation, shipping, science and computing because it never changes.
Why is Australia 9 or 10 or 11 hours ahead of London?
Three things stack up. First, eastern Australia (Sydney, Melbourne) is naturally UTC+10. Second, those states observe daylight saving in their summer (October to early April), shifting to UTC+11. Third, the UK observes BST in its summer (March to October), shifting London to UTC+1. So the net difference between London and Sydney runs 9 hours (UK summer, AU winter), 10 hours (when offsets line up), or 11 hours (UK winter, AU summer).
Is there a single timezone for the whole of China?
Yes, China Standard Time (UTC+8) covers the entire country despite spanning what would naturally be five time zones. This means sunrise in Kashgar (far western China) can be as late as 10am local time. The decision was political rather than astronomical, made in 1949.
How accurate is the converter?
Accurate to the minute for any current or future date. Historical conversions before about 1970 may be approximate because daylight saving rules and time-zone boundaries have shifted over the decades, and the IANA timezone database (which JavaScript uses) handles the modern era reliably but has fewer rules for older periods.
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