About Changetz

Changetz is a free tool for the single most annoying part of working with people in other countries: agreeing on a time.

What it does

You add the cities your colleagues, clients or family are in, and the whole day appears as one grid. Every column is the same instant everywhere, so you can see at a glance who is at their desk, who is having dinner and who is asleep. The hours that work for everybody are highlighted, so you do not have to work it out yourself.

How the recommendation is calculated

Each hour is scored against every city on your list. A time inside 9:00–17:00 local scores best, 8:00 and 17:00 are still fine, and 7:00, 18:00 and 19:00 are workable but not pleasant. Anything else scores zero.

The slot that wins is the one with the best worst case, not the best average. A meeting is only as good as it is for the person it suits least, and averaging would happily suggest 3 a.m. for one person so that four others get a perfect 10 a.m. When no hour works for everyone, we say so instead of pretending.

Where the data comes from

Time zone rules, including daylight saving dates, come from the IANA time zone database that is already built into your browser and kept up to date by its vendor. Nothing is calculated on a server, and no clock data is fetched over the network.

Contact

Corrections, missing cities, bugs: hola@changetz.com.