How it is worked out
destination time = origin time − origin offset + destination offset
Why it is done this way
Converting a time means going through universal time: strip the local offset to get the real instant, then add the offset of the destination city. Because the offset depends on the date, you have to give the day and not only the time.
Step by step
- Enter the date and the time in the origin city
- Subtract that city's offset to get universal time
- Add the offset of the destination city
- If the result falls outside the 24 hours, the day changes
What is worth knowing
What catches people out is not the time, it is the day. Between Europe and East Asia any afternoon meeting lands in the small hours of the next day, and between Europe and the American Pacific, in the morning of the day before. That is why this page shows the destination date next to the time: giving only the clock reading is half an answer.