How Do Timezones Get Determined for the Customer?

When a customer opens your booking page, the time slots they see are generally shown according to the timezone their own browser or device reports — not your business's timezone, and not a timezone they have to manually set.

How automatic detection works

Most booking widgets read the visitor's local timezone directly from their browser and adjust all displayed slots to match it. A customer in a different timezone than your business sees times already converted to their own local time, so a 3 PM slot in your timezone might correctly show as 12 PM to a customer three hours behind you.

Where this can go wrong

• VPNs and travel — a customer using a VPN, or traveling somewhere their device hasn't updated its timezone for, can be shown times based on a location that isn't actually where they are.
• Manually set device clocks — a device with an incorrect manually-set timezone will pass that incorrect timezone along to the booking page.
• Calendar-level timezone overrides — if a specific calendar is locked to a fixed timezone (common for a physical-location business where you want every customer to see local time regardless of where they're browsing from), that overrides browser detection intentionally — which is correct behavior for that use case, but worth knowing about if you're troubleshooting a report of "wrong" times.

What to check if a customer reports the wrong time

Confirm whether the calendar involved has a fixed timezone override configured. If it does, that's expected behavior for a location-based booking. If it doesn't, the discrepancy is most likely on the customer's device or browser rather than your calendar setup.

Good to know: Always show the timezone label alongside times in confirmation and reminder messages — a specific time without a timezone label is one of the most common sources of no-show confusion.