ToolWren"Is that 3pm my time or yours?" Time zones cause more missed meetings and travel mix-ups than almost anything else. The rules are simple once you know them — and one common trap catches nearly everyone. Here is how to convert times correctly.
Everything is an offset from UTC
The world keeps time relative to one reference: Coordinated Universal Time (UTC). Every zone is expressed as an offset — London is UTC+0 in winter, New York is UTC−5, Tokyo is UTC+9. To convert between two cities you take the difference between their offsets. Our time zone converter does this instantly and shows the exact hour gap.
Not all offsets are whole hours
A surprising number of places are offset by 30 or even 45 minutes. India is UTC+5:30, Nepal is UTC+5:45, and parts of Australia use UTC+9:30. If you assume every zone is a round number of hours you will be off by half an hour — a small error that still derails a call.
The daylight saving trap
This is the big one. Many countries shift their clocks forward an hour in spring and back in autumn — but on different dates, and some do not do it at all. So the gap between two cities is not fixed. London and New York are usually five hours apart, but for a couple of weeks each year, when one has changed and the other has not, they are four or six. This is why a good converter uses the real calendar date, not a fixed offset — pick July and January in the time zone converter and you will see the difference change.
Tips for scheduling across zones
Three habits save a lot of pain: 1) state the zone explicitly ("3pm London time"), ideally with UTC in brackets; 2) convert for a specific date so daylight saving is applied correctly; and 3) for anything technical, store and share times in UTC and convert only for display. Developers often work in Unix timestamps, which are always UTC-based and sidestep the whole problem.
Related date and time tools
Once times line up, the rest is date maths. Add or subtract intervals with the date add/subtract tool, measure the gap between two dates with the date difference calculator, or translate epoch values with the Unix timestamp converter. Everything runs in your browser — nothing is uploaded.