How to Track Time Zones Across Client Calendars

Three clients, three clocks, one tired brain

A client in New York, a client in London, a client in Singapore. Every scheduling email becomes arithmetic: "2pm my time is 7pm theirs, no wait, is London on summer time yet?" Tracking time zones across client calendars in your head works fine right up until it does not, and the failure is always public: you, alone in a meeting room, at what turned out to be 4am for the other person.

The fix is not more mental math. It is putting the answer on the screen, next to the calendar where you actually make scheduling decisions.

Where mental conversion breaks down

Offsets feel learnable, and they are, until daylight saving moves the goalposts. The US and Europe change on different weeks, so for a stretch every spring and fall your memorized "London is plus five" is quietly wrong. The southern hemisphere shifts the opposite direction. And past a certain longitude you hit the day boundary: a Friday afternoon call from the US east coast is Saturday morning in Sydney, which no amount of hour-counting will flag if you forget to also count the date.

Each client's own calendar shows times in its zone, your zone, or some setting you configured once and forgot, which makes flipping between calendar tabs worse than useless for this. You need every clock in one place, next to one merged view of every commitment.

Step by step

Step 1: Merge the calendars first

Install manyCalendars from the checkout page, 14-day full trial, no card, no account. Add each client calendar as an .ics file or feed URL, or use Tab Sync for the ones you cannot export: open the calendar in a tab you are signed into and the calendar follows that tab, read-only on the source. Now every commitment sits in one grid instead of five tabs.

Step 2: Open Manage Timezones

Next to the merged calendar sits a strip of live clocks. Click + Manage Timezones to open the picker.

Step 3: Add a clock per client city

Pick from presets covering the four US zones, UTC, London, Paris/Berlin, Athens, Dubai, Mumbai, Bangkok, Singapore, Tokyo, Sydney, Auckland, São Paulo, Mexico City, and more. Your local clock stays pinned, so you always have the reference point.

Step 4: Drag them into the order you think in

West to east reads like a map. By client priority reads like your week. Either way, drag the clocks into an order that matches how you plan, and it sticks.

Step 5: Read the day marker before you propose a time

Each clock shows the city, the live time, the date, and the zone abbreviation. When a city's date differs from yours, a small +1d or -1d marker appears. That marker is the whole ballgame for APAC scheduling: if Sydney says +1d, your Friday afternoon is their Saturday, pick another slot.

Step 6: Send times in their zone, not yours

When you share availability, the summary can be expressed in the recipient's time zone, so "9am - 11am" already means their 9am. No conversion on either end of the email. (Share availability is a Premium feature; the clocks themselves come with Pro.)

Honest limits

The clocks answer "what time is it for them right now." The merged calendar grid itself stays in your local time, which we think is the right call, since your body is only ever in one zone. Daylight saving is handled automatically by your browser's time zone database, so the strip is correct on changeover weekends without you touching anything.

manyCalendars is a desktop browser extension for Chrome, Edge, and Firefox. Tab Sync reads what is visible in a tab you are signed into, and it never writes to the source calendar.

What it costs

Time zones ship in Pro, $15/month or $150/year ($12.50/month equivalent), together with Tab Sync, meeting reminders, custom work-week view, and .ics export. The 14-day trial includes everything, compare tiers on the pricing page. And because it all runs locally, nobody's IT department needs to approve anything, the topic of our full guide to calendar access without admin approval.

FAQ

Do the clocks handle daylight saving?

Yes, automatically, via your browser's time zone database. When London springs forward, the strip already knows.

Can I view the whole grid in a client's zone?

The grid stays in your local time. Use the clocks for "their time right now" and the availability summary for slots in their zone.

Is there a mobile app?

No. Desktop browser extension only, for Chrome, Edge, and Firefox.