Convert a date and 24-hour clock time between fixed UTC offsets or use the named-zone meeting planner. The calculator handles date-line changes and the half-hour and quarter-hour offsets used in several regions.
How to convert time zones
- Enter the local date and time at the source location.
- Choose the source's UTC offset that applies on that date.
- Choose the destination's UTC offset for the same instant.
- Read the converted clock time and check whether the date moved to the day before or after.
The safest workflow for a meeting is to confirm both offsets for the meeting date, because daylight-saving transitions do not always happen on the same day in different countries. Use the Time Calculator to add a duration to a clock time, or the Date Calculator to count calendar days.
Fixed UTC offsets versus named time zones
An offset such as UTC−05:00 is a numeric difference from Coordinated Universal
Time. A named zone such as America/New_York is a ruleset: its offset can change
with daylight saving time and its historical rules. The IANA Time Zone Database
records these regional rules and is updated when governments change civil time.
Fixed-offset mode deliberately uses explicit offsets. It is useful when the applicable offsets are already known, for checking aviation or server timestamps, and for converting values that explicitly include an offset. It should not be used to guess the offset of a city on a future or historical date.
Date-line and non-hour offsets
The difference between the selector's UTC−12:00 and UTC+12:00 endpoints is 24 hours, so the destination can be one calendar day ahead even though both clocks describe the same instant. The selector also supports offsets such as UTC+05:30 and UTC+05:45; rounding these to whole hours would produce a wrong result.
Examples
UTC−12 to UTC+05:30
September 13, 2026 at 15:03:09 in UTC−12 becomes September 14, 2026 at 08:33:09 in UTC+05:30.
UTC to UTC+05:45
00:15 UTC becomes 06:00 in UTC+05:45 on the same date.
Crossing to the previous day
January 2 at 01:00 in UTC+02:00 is January 1 at 18:00 in UTC−05:00.
Formula
destination time = source time + destination UTC offset − source UTC offset
When the result is below 00:00 or at least 24:00, the calendar date moves backward or forward. Seconds are preserved throughout the conversion.
Sources
Fixed-offset limitation
Fixed-offset mode converts explicit UTC offsets. It does not infer daylight-saving time from a city name or historical date. Political decisions can change offsets, and duplicated or skipped local times occur during clock changes. For a meeting, use the named-zone planner below. The IANA Time Zone Database is the maintained source used by operating systems for location rules.
Named zones and meeting planning
The Meeting planner uses a date, source local time and an IANA zone such as
America/New_York. Add locations such as Europe/London, Asia/Kolkata and
Australia/Sydney, one per line. The result table shows local start/end dates,
UTC offsets and whether the meeting fits a weekday 09:00–17:00 reference window.
That window is illustrative and does not account for holidays or personal hours.
Unlike fixed offsets, named zones use date-specific rules from the runtime's maintained IANA-backed Intl database. For example, 09:00 New York corresponds to 14:00 UTC on January 15, 2026, and 13:00 UTC on July 15, 2026.
A skipped local time produces an error rather than silently moving the meeting. A repeated local time asks you to select the earlier or later occurrence. Meeting duration is elapsed time, so a clock change can change the apparent wall-clock duration. Supported named-zone dates are 1970–2100. Keep the browser and server runtime updated and reconfirm future events when governments change rules; browser and server data versions can differ. This is a one-meeting planner, not a recurring calendar scheduler.
The existing Fixed offsets mode retains its original behavior. Its location labels are illustrative; it does not apply daylight-saving rules.
- IANA time-zone data — maintained historical and current civil-time rules.