Sharing a schedule across time zones

If the people who need your schedule are in a different time zone, there is a whole extra failure mode, and it produces the same two problems every time: calls at the wrong hour, and plans made against times that were never right.

Why it goes wrong so reliably

The conversion is easy in principle and gets done badly in practice, because of four compounding things.

It is done by the wrong person. The shift worker knows their own times. The person calling has to convert, from memory, against a schedule they half-remember.

Daylight saving is not synchronised. The UK and the US change clocks on different dates, so for a few weeks each year the offset is not what everyone learned. This is when most of the errors happen.

Some places do not observe it at all. Arizona, most of Asia, most of Africa. The offset people memorised is only right for part of the year.

Written times lose their zone. “I’m working 7 to 7” contains no zone. Whoever reads it assumes their own.

What removing it looks like

The fix is not to convert more carefully. It is to stop asking anyone to convert.

If the schedule is shared through something that stores times with a zone and displays them in the reader’s own, the arithmetic disappears — your 19:30 finish shows as 02:30 to somebody in London, and nobody had to work it out or remember which weeks the offset is different.

That is what Freeish does, and it is the main reason it comes up for travel nurses and flight crew, where the zone changes as well as the schedule. A calendar subscription has the same property: the feed carries real timestamps, and the subscriber’s calendar renders them locally.

What does not have this property: a photo of a rota, a message saying “7 to 7”, or a printed schedule. All of those carry times with no zone attached, so the conversion falls back to a human.

If you are doing it manually anyway

Sometimes you cannot avoid it — a printed rota to a parent abroad, a message to somebody who will not use anything.

Three things reduce the error rate:

State the zone explicitly, every time. “19:30 my time (Denver)”. Never a bare number.

Give their time as well. “I finish 19:30 here, which is 02:30 for you.” Doing the conversion for them is more reliable than asking them to.

Flag the daylight saving weeks. In spring and autumn there are a few weeks where the usual offset is wrong. A single message saying “the difference is 7 hours this fortnight, not 8” prevents most of the year’s errors.

The sleep window matters more than the shifts

For long-distance relationships and families abroad, the genuinely useful information is not when you are working. It is when you are asleep — because that is what determines whether a call lands well.

Somebody working nights in a distant zone has a sleep window that is deeply counter-intuitive to everyone at home, and the thing that stops the 3am calls is putting the sleep in as a visible block rather than expecting people to infer it from the shift.

That single addition removes more friction than any amount of careful conversion.