Time Zone Calculator

The Formula

Convert a time from one time zone to another by accounting for the UTC offset difference between the two zones. Every time zone has a UTC offset (e.g., EST is UTC-5, PST is UTC-8). To convert, first normalize the source time to UTC by subtracting its offset, then apply the target offset to get the local time in the destination zone. This two-step process ensures accuracy regardless of which direction the conversion goes.

Variable Definitions

How to Use This Calculator

1. 1

   Select the source time zone (the zone you know the time in) from the dropdown list.

2. 2

   Select the target time zone (the zone you want to convert to) from the dropdown list.

3. 3

   Enter the time in either 12-hour format (e.g., 2:30 PM) or 24-hour format (e.g., 14:30).

4. 4

   Optionally select a date so the calculator can account for Daylight Saving Time offsets.

5. 5

   Enable "Business Hours Overlay" to see when the standard 9 AM-5 PM workday overlaps between the two zones.

Time zone conversion adjusts for UTC offset differences; business hours overlay shows when work schedules overlap.

Understanding the Concept

Time zone conversion accounts for the difference in UTC offsets between regions. The calculator determines the offset for the source and target zones, computes the difference (target offset minus source offset), and applies it to the entered time. A positive difference means the target time is ahead (later in the day), and a negative difference means it is behind (earlier in the day). The Business Hours Overlay shows when the standard 9 AM-5 PM workday overlaps across both zones, which is essential for scheduling international meetings, conference calls, and remote collaboration across time zones. The overlay color-codes each hour block: green when both zones are within business hours, yellow when only one is, and gray when neither is.

Frequently Asked Questions

Sources & References