Setting Your Computer Clock to the Right Time Zone

I used to assume my laptop always knew the time. Then a client call appeared on my calendar an hour before I expected it, and I spent twenty minutes convinced the calendar was broken. It wasn’t. My system clock had quietly landed in the wrong zone after I restored a backup from a trip.

Here is the order I check things in now.

Automatic versus manual. Most operating systems offer a switch for setting the time zone automatically. I leave it on for my desktop, which never moves. For my travel laptop I often turn it off, because location detection can be slow or simply wrong on a hotel network, and I would rather set the zone myself than have it shift in the middle of a workday. Either way, I check that setting after any restore or major update.

VPNs and location. Automatic detection usually leans on network location rather than a GPS chip. If a VPN is running, the machine may decide I am in another country and adjust the clock to match. I have had that happen with a work VPN that routes through a different region. Now I disconnect, let the clock settle, and confirm the zone by hand.

UTC offset. This is the part that made time zones click for me. Every zone is described as an offset from UTC, something like UTC minus five. When I compare two machines, I compare offsets rather than city names, since names can be ambiguous and offsets are not.

Browser versus system time. When a website shows you a time, it usually reads your system clock rather than its own. So if the browser looks wrong, fix the system first. I test by opening What Time Zone Am I In and comparing the zone and offset it reports against what my machine’s settings say. If those two disagree, I know where to look.

That routine takes about a minute, and it has saved me more than one early morning.

— Chris Walker