Time Zone Calculator

Convert a time from one zone to another, check how many hours apart two zones are, or pull up the current time in several zones side by side — pick the zones from their standard abbreviations and see the offset math laid out step by step.

For personal planning and general reference — verify important results when needed.

Start converting

Your Input

Format: HH:MM or HH:MM:SS (e.g., 14:30 or 14:30:45)

Select a calculation type, enter time and timezones (or pick zones for difference/current), then click Calculate to see results with step-by-step solution.

Why every zone is really just an offset from UTC

Every time zone in this tool is defined the same way: a number of hours (sometimes a half hour, as with India) added to or subtracted from Coordinated Universal Time, UTC. UTC itself doesn't observe daylight saving and doesn't belong to any single country, which is exactly why it works as a stable reference point that every local zone can be measured against.

UTC offsets for common time zone abbreviations
Zone UTC offset
PST / PDTUTC−8 / UTC−7
EST / EDTUTC−5 / UTC−4
GMT / CETUTC+0 / UTC+1
ISTUTC+5:30
JSTUTC+9
AEST / AEDTUTC+10 / UTC+11

The two-step math behind a conversion

Converting directly between two arbitrary zones is really two simpler steps chained together: go from the source zone to UTC, then from UTC to the target zone.

UTC time = Source time − Source offset

Target time = UTC time + Target offset

14:00 PST (UTC−8) → UTC = 22:00 → CET (UTC+1) = 23:00

That's also why the difference between two zones is just the difference between their two offsets — PST to CET is (+1) − (−8) = 9 hours, no UTC conversion needed if all you want is the gap rather than an actual converted time.

The one detail that breaks most manual conversions

Daylight saving time means many zones have two valid offsets depending on the time of year, and this tool lists them as separate options (EST vs. EDT, CET vs. CEST) rather than guessing automatically from a date. Picking standard time when daylight time is actually in effect for the date in question — or the reverse — is the single most common source of an hour-off scheduling mistake, and it's worth double-checking which one applies before locking in a meeting time across regions.

When a conversion changes the date, not just the time

A late-evening time in one zone can land in the small hours of the next calendar day somewhere else, which affects more than just the clock reading — it can shift which day of the week an event falls on locally. If a converted time crosses midnight and you need to confirm the actual day of the week it lands on, the day of week calculator and the general-purpose time calculator both help fill in that piece.

Frequently Asked Questions

What is a time zone?

A time zone is a region using the same standard time, usually an offset from Coordinated Universal Time (UTC). Offsets range from UTC−12 to UTC+14.

How does daylight saving time affect conversions?

Many zones shift clocks forward or back seasonally. Conversions must use the correct date — a meeting in March may differ from one in July for the same cities.

What is UTC and why use it?

UTC is the global time standard without daylight saving. Pilots, software systems, and international scheduling often store and convert via UTC internally.

Why do meeting times confuse people across zones?

People forget DST rules differ by country. Always state the zone abbreviation (ET, PT) or offset (UTC−5) and verify the calendar date.

How do I use this time zone calculator?

Select source and destination zones, enter a date and time, and click Convert. Equivalent local times and UTC offset appear in the results.

Should I pick the standard or daylight version of a zone?

Whichever one is actually in effect on the date you care about. EST (UTC-5) and EDT (UTC-4) describe the same US East Coast region, but daylight saving shifts the clock an hour for part of the year, so the offset genuinely changes. Picking the wrong one for the season is the single most common source of a wrong conversion.

Can a time zone conversion land on a different calendar day?

Yes. Converting 23:00 UTC to JST (UTC+9) lands at 08:00, but that 08:00 is already the next calendar day in Japan. This calculator gives you the time of day; keeping track of whether that time falls on the same day, the next day, or the previous day is worth double-checking separately for anything date-sensitive.

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