A complete guide to comparing time zones, finding meeting windows, and sharing time references with your team.
When you open the calculator, you'll see three default columns: New York (ET), London (GMT), and Tokyo (JST). Each column shows all 24 hours of the day for that location. The orange dot marks the current live hour. This lets you instantly answer "what time is it there right now?" without any arithmetic.
To add a city, click the + button at the right edge of the grid. Type any city name or IANA timezone identifier (e.g., "Asia/Singapore" or "Europe/Berlin") and select from the dropdown. You can display up to 10 zones simultaneously. Reorder columns with the ◀ ▶ arrows in each zone header, or remove a zone with the ✕ button.
By default, the grid tracks live time — the orange dot updates every second. To ask "what time is 3 PM New York for London and Singapore?", tap or click any row in any column. This pins that hour, highlighting the corresponding row in every other column in blue. A "Pinned: X:00" indicator appears in the header. Tap the same row again, or click Reset to now, to return to live mode.
Click the Meeting button in the top-right corner to switch to Meeting Finder mode. A horizontal bar appears at the top of the page, showing each hour of the day color-coded by how many participants are within their working hours. Inside the zone grid, rows where everyone is within business hours glow green — these are your ideal meeting slots.
Use the working-hours controls to adjust the business window per session. For example, if a Sydney colleague works 8 AM–4 PM, adjust the end hour earlier. The overlap highlights update instantly. Tap any green row to pin it as your candidate time.
Once you've pinned a time, two extra actions appear in the action bar:
2026-05-19T15:00:00-05:00). This format is accepted by nearly every calendar app, scheduling API, and communications tool, and eliminates the "was that your 3 PM or mine?" ambiguity.Press Share to copy a URL that encodes your current configuration — which zones are shown, which hour is pinned, and whether Meeting Finder is active. Paste the link into Slack, email, or a calendar invite. Anyone who opens it sees exactly the same view, with no account or login required.
Every calculation uses the browser's built-in IANA timezone database, which includes DST rules for every region worldwide. Each zone header displays whether DST is currently active (e.g., "ET (DST)") and shows the current UTC offset. When a pinned date falls across a DST boundary, offsets update automatically — no manual adjustment needed.
Toggle between 12-hour (AM/PM) and 24-hour display using the format button in the top-right corner. The 24-hour mode is preferred by engineers, travelers, and anyone accustomed to European or military time notation.
How many time zones can I compare at once?
Up to 10 zones simultaneously. The grid scrolls horizontally so you can compare as many as you need without losing context.
Does it work offline?
Yes. All timezone calculations run entirely in your browser using the built-in Intl API. No server calls are made for time conversions.
Is there a mobile app?
An Android app is in progress and will be available on Google Play. The web version is fully mobile-responsive and works well on all screen sizes.
Which timezones are supported?
The calculator includes 47 curated IANA timezones covering major cities on every continent, including all North American, European, Asian, and Oceanian business hubs. Full DST awareness is included for all regions.