worldclock.tools

Converters & time math

Time difference calculator

How far apart are two places, right now? Pick any two cities and see the exact difference — ahead or behind — with both live clocks side by side.

Tokyo is of London
London
United Kingdom
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Tokyo
Japan
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How to use the time difference calculator

  1. Choose two cities

    Pick the pair you want compared. Both are resolved to their own IANA zones rather than to a country-level assumption.

  2. Read the difference

    You get the gap in hours and minutes and the direction — which city is ahead — plus each city's current local time for context.

  3. Watch for the odd offsets

    Differences are not always whole hours. Anything involving India, Nepal, parts of Australia or Newfoundland lands on a 30- or 45-minute boundary.

  4. Remember it is date-dependent

    The number shown is for today. If the pair straddles a daylight-saving boundary, check the difference for the specific date you care about rather than reusing this one.

The difference between two cities is not a constant

People memorise time differences as facts — "Berlin is nine hours ahead of California" — and then act on them all year. For a few weeks each spring and autumn, that number is wrong by an hour, because the two regions change their clocks on different dates. Between hemispheres it is worse: the difference between London and Sydney varies by two hours across the year as the two sides move in opposite directions.

Non-integer offsets catch people out too. India sits at UTC+5:30, Nepal at UTC+5:45, the Chatham Islands at UTC+12:45. A difference of "eight and a half hours" is not a rounding error, and a meeting scheduled on the assumption of whole hours will be thirty minutes out.

Then there is the calendar day. Once a difference exceeds about twelve hours, the two cities are frequently on different dates, and a difference expressed only in hours hides that. "Fourteen hours ahead" and "ten hours behind, tomorrow" describe the same relationship, and only one of them makes the meeting invite readable.

All of which is why the useful habit is to check the difference for the date in question rather than to remember it. The computation is free; the meeting that lands an hour off is not.

When you'd reach for it

Before you call

Check the gap and their current local time so you are not dialling at midnight.

Quoting a lead time

Express a turnaround in the client's local terms rather than yours.

Comparing job offers

Judge how many hours of overlap a remote role would really give you with the team.

Sports and live events

Work out how far into your night a fixture in another country falls.

Travel planning

Estimate how many hours your body clock will need to shift.

Checking a stated offset

Verify a difference someone has asserted, on the actual date it applies to.

Questions & answers

How is the difference calculated?
From each city's live UTC offset for the current moment, so daylight saving is already baked in on both sides. The result is the real gap right now, not a fixed table value.
Why can the difference include half hours?
Some zones — India (+5:30), parts of Australia (+9:30), Nepal (+5:45) — are offset by fractions of an hour, so the difference between two cities can be 30 or 45 minutes off a whole number.
Does it stay correct across DST changes?
Yes. Because the offsets are resolved live, the difference updates automatically when either city springs forward or falls back.