KKoumen Tools PRO

Before you book the call.

Pick a time and two places. Day changes included, daylight saving handled.

In New York
11:09 AM
Date thereSun, Nov 1
Difference−13h
Date hereMon, Nov 2

Finding a time that works in two places

The hard part of time zones is not the offset, it is daylight saving — and the fact that countries change on different dates, or not at all. This tool uses the browser’s built-in time zone database, which knows the rules rather than just the offset.

  1. Pick a time and a city. Enter the time in the place you are, then choose the city you want to compare. The tool shows what that moment is in the other city, plus the offset difference.
  2. Read the day marker. When a conversation spans more than a dozen hours, the date on the other side changes. A call at 9am in Los Angeles is the next day in Shanghai, and the result says so explicitly rather than leaving you to work it out.
  3. Compare several cities at once. Add cities to see them side by side. This is the useful shape for scheduling across a team, where "does this work for everyone" is the actual question.
  4. Check around a DST change. Set a date near a transition and the offsets update. This is the case that catches people out: for two weeks each spring and autumn, the US and Europe are a different number of hours apart than they are for the rest of the year.

When this comes up

Questions

Why do the offsets change during the year?

Because most of Europe and North America observe daylight saving, but they start and end it on different dates and in opposite hemispheres. Between mid-March and late March, New York and London are 4 hours apart; for the rest of the year they are 5. The tool reads the actual rules for the date you enter rather than assuming a fixed offset.

Which time zones do not observe daylight saving?

Most of Asia and Africa, including China, Japan, India, and the whole of Russia. Arizona in the US and Saskatchewan in Canada also skip it. This is why an offset that works in January can be an hour wrong in July.

What is the difference between UTC and GMT?

In everyday use, nothing — they are the same clock. Strictly, GMT is a time zone and UTC is the time standard that time zones are defined against. For scheduling purposes, treat them as identical.

Why is China one time zone despite being the width of a continent?

Because the country legislated a single standard time, UTC+8, in 1949. In the far west the sun rises around 9am in winter, which is why some western regions keep unofficial local time. If you are scheduling with someone in Xinjiang, it is worth asking which clock they mean.

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