Of course! A timezone overlap calculator is essential for scheduling meetings across different teams. Here’s a comprehensive guide, covering the core concepts, tools, and best practices, specifically tailored for teams like yours.

The Core Concept: Finding the Overlap

The goal is to find a "window of time" that falls within the standard working hours (e.g., 9 AM - 5 PM) for all team members, regardless of their timezone.

Example:

• Team Member A: PST (UTC-8) working 9 AM - 5 PM


• Team Member B: CET (UTC+1) working 9 AM - 5 PM


• Team Member C: IST (UTC+5:30) working 9 AM - 5 PM

Method 1: Automated Tools & Websites (Easiest)

These are the fastest and most reliable options for teams.

1. World Time Buddy

• How it works: You add multiple timezones in a visual, side-by-side comparison. The interface clearly highlights overlapping working hours.


• Best for: Quick, ad-hoc scheduling for a handful of people.


• Link: worldtimebuddy.com

2. SavvyCal

• How it works: A modern scheduling tool that shows your availability and lets invitees choose a slot that works for them. It automatically handles the timezone conversion for the recipient.


• Best for: External meetings (client calls, interviews) where you want to avoid back-and-forth emails.


• Link: savvycal.com

3. Microsoft Teams / Google Meet Integration

• How it works: When you schedule a meeting in these platforms, they automatically detect the attendees' timezones (if they are in the same organization). The "Scheduling Assistant" in Outlook/Teams shows a grid of free/busy times across timezones.


• Best for: Internal teams that already use the Microsoft 365 or Google Workspace ecosystems.

Method 2: The Manual Method (Good for Understanding)

Sometimes it's helpful to do it manually to understand the logic.

• Convert Everyone to UTC: Convert all local working hours to Coordinated Universal Time (UTC). This creates a common baseline.


• New York (EST/UTC-5) 9 AM - 5 PM becomes 2 PM - 10 PM UTC


• London (GMT/UTC+0) 9 AM - 5 PM becomes 9 AM - 5 PM UTC


• Singapore (SGT/UTC+8) 9 AM - 5 PM becomes 1 AM - 9 AM UTC


• Find the Overlapping UTC Window:


• Look at the earliest end time and the latest start time in UTC.


• Earliest End Time: 9 AM UTC (Singapore ends at 9 AM UTC)


• Latest Start Time: 2 PM UTC (New York starts at 2 PM UTC)


• Overlap: In this case, there is no overlap during standard working hours.


• Adjust Working Hours: To find a meeting time, someone would need to be flexible. If the Singapore team member can stay until 6 PM (10 AM UTC) and the New York member can start at 8 AM (1 PM UTC), a small window from 1 PM UTC to 10 AM UTC (a 1-hour window) opens up.

Pro Tips for Teams

• Establish Team "Anchor Hours": Agree on a 2-4 hour block each day where everyone is expected to be available. This guarantees a window for collaboration and meetings. (e.g., "Our team anchor hours are 9 AM - 11 AM PST / 12 PM - 2 PM EST / 5 PM - 7 PM GMT").


• Leverage Async Communication: Not every discussion needs a meeting. Use tools like Slack, Microsoft Teams, or Loom (for video updates) to communicate without needing everyone online at once.


• Rotate Meeting Times: If your team is split between, for example, the US and Asia, don't make one region always take the late-night call. Rotate the meeting time bi-weekly or monthly to share the inconvenience fairly.


• Use a Shared World Clock: Add a world clock widget to your team's Slack channel or intranet homepage showing the key timezones of all team members for a quick visual reference.


• Be Explicit with Time: When scheduling, always state the time in both the local time for the meeting and UTC.


• Good: "Standup at 9:30 AM PST (17:30 UTC)"


• Bad: "Standup at 9:30 AM"

Quick-Start Recommendation for Your Team

• For a quick, one-off calculation: Use World Time Buddy.


• For a permanent, integrated solution: Use the Scheduling Assistant in Microsoft Teams or Google Calendar.


• For scheduling with people outside your org: Use SavvyCal or Calendly.