Time Zone Converter

// Why the gap between two zones keeps moving

The difference between two time zones is not a constant you can memorise. New York and London sit five hours apart for most of the year, but only four for the three weeks between the US spring-forward in early March and Europe's on the last Sunday of the month — and four again for the week between Europe falling back in late October and the US doing so in early November. Any tool that stores a fixed offset per zone gets those weeks wrong, and those are exactly the weeks people miss calls.

This converter stores no offset. It asks your browser's own time zone database what was in force on the date you picked: New York on 14 March is EDT (UTC-4); on 14 January it is EST (UTC-5). Change the date and the label changes with it, which is why the date field matters as much as the time field.

// EST, EDT, and the abbreviation trap

Most people type EST when they mean Eastern Time. For roughly eight months of the year that is wrong by an hour — the US east coast runs on EDT from the second Sunday in March to the first Sunday in November — and the same holds for PST versus PDT, CST versus CDT, and GMT versus the UK's summer BST. The pickers list those abbreviations because they are what people search, but each one selects a region rather than a frozen offset: pick EST and the tool tells you EDT is what is actually in force on the date you chose. GMT is the exception, treated literally as UTC+0; for British local time pick London, and you will see BST in summer.

Under each side's fields is the line that settles it — EDT · UTC-4 · America/New_York: the abbreviation in force, the offset it means, and the IANA identifier that calendar files, servers and scheduling systems actually use. That identifier is the unambiguous form, and it is worth pasting into a meeting invite when the stakes are high.

// How to use it for a meeting

The page opens on two live clocks — the pair a link named, or your own zone and the one you are scheduling into — and one conversion between them, seeded with the current moment. Type into either side's time or date and the other recalculates from it: there is no source field and no direction to get backwards, because whichever side you touched is the source. The swap button exchanges the pair without retyping anything.

Underneath, the whole day is laid out an hour at a time in both cities, with the current hour marked and a moon, sunrise, sun or sunset on every row, so the working hours on both ends are visible at a glance. On the two days a year a clock change makes the local day 23 or 25 hours long, the table is that long too, rather than quietly dropping an hour. When a city has already rolled past midnight the line under the fields says so — the failure mode that actually bites when scheduling with Asia or Australia. The pair travels in the page's address, so a link to this view is just the URL in your bar.

// fair questions

What's the difference between EST and EDT?

EST is Eastern Standard Time (UTC-5), used from early November to mid-March. EDT is Eastern Daylight Time (UTC-4), used the rest of the year. People write EST year-round out of habit, which is why this tool shows you which one is actually active on the date you picked rather than trusting the abbreviation.

Does the time difference between two zones change with daylight saving?

Yes, and not always at the same moment on both sides. Europe switches on the last Sunday in March and October; the US switches in mid-March and early November. For those in-between weeks the usual gap shifts by an hour. Pick the real date of your meeting and the converter accounts for it.

What time is 3 PM Eastern in Pacific time?

Noon. Pacific runs three hours behind Eastern all year, because both zones start and end daylight saving on the same dates — so this particular pair keeps a constant gap even though the offsets themselves move.

What time zone is UTC and why do people schedule in it?

UTC is the global reference at zero offset, and it never observes daylight saving. Teams spread across many countries schedule in UTC precisely because it cannot drift: one fixed instant that every local clock can be derived from.

How many time zones are there?

There are 38 distinct UTC offsets in use, not 24 — several places run on half-hour or 45-minute offsets, including India (UTC+5:30), parts of Australia, and Nepal (UTC+5:45). The zone list here covers every region your browser's database knows about, so those are handled correctly.

Does anything I enter get sent anywhere?

No. Conversions are computed in your browser using the time zone database it already ships with, so the page makes no requests while you use it and keeps working offline once loaded.