Time Zone Converter

Plan meetings across time zones by converting a date and local time into another named time zone.

Choose the source calendar date.
Enter the hour in 24-hour time.
Enter the minute value.
Choose the time zone for the starting time.
Choose the time zone you want to convert into.

Converted local time

22:30 (GMT+9)

Target dateMar 10, 2026
Offset difference13
Calendar shiftSame calendar day

How to use this time zone converter

  1. Choose the date

    Select the calendar date in the Date field.

  2. Enter the source time

    Type the hour and minute in the Source hour and Source minute fields using 24-hour time.

  3. Select the time zones

    Choose the starting zone in Source time zone and the destination zone in Target time zone.

  4. Read the converted time

    Review the converted local time, target date, offset difference, and calendar shift.

Methodology

How this time zone converter works

This time zone converter translates a date and local time from one named IANA time zone to another, reporting the resulting local time, the calendar date in the target zone, and whether the day shifts forward or backward. The method first resolves the source wall-clock time into UTC using the source zone's daylight-saving-time rules for that date, then formats the same instant in the target zone. That mirrors how calendaring systems, airline schedules, and international meeting tools handle timezone-aware timestamps.

Formula
UTC instant = resolve(source date + source local time + source time zone rules) Target local time = format(UTC instant in target time zone)
source local time The hour and minute you enter for the source location
UTC instant The timezone-neutral moment created after applying the source zone's offset rules for that date
target local time The wall-clock time shown in the target zone for that same instant
offset difference The signed gap between the target zone offset and the source zone offset on the selected date
day shift Whether the target local date falls on the same day, previous day, or next day relative to the source date
Example

Suppose a team in New York wants to schedule a call at 09:30 on March 10, 2026 and needs the London time. New York is already on daylight saving time by then (UTC−4), while London is still on GMT (UTC+0), so the offset gap is 4 hours rather than the 5 hours many people expect from winter. The converter therefore shows 13:30 in London on the same calendar day.

A developer in Tokyo (JST, UTC+9) wants to join a standup at 10:00 on June 15 in Los Angeles (PDT, UTC−7). The offset gap is 16 hours, so the standup falls at 02:00 on June 16 in Tokyo — the next calendar day.

Assumptions
  • ✓ The converter uses named IANA time zones and applies daylight saving time automatically for the date you enter.
  • ✓ The available zone list is intentionally curated to common planning regions rather than every IANA zone identifier.
  • ✓ The calculation assumes a 24-hour clock. Input hours outside the 0–23 range or minutes outside 0–59 may produce unexpected results.
  • ✓ Offset differences can change during the year when one region has entered daylight saving time and another has not.
Notes
  • DST transitions can temporarily shrink or widen the gap between two cities, so the offset difference is date-specific rather than fixed year-round.
  • Some regions use non-standard offsets such as UTC+5:30 or UTC+12:45. Named-zone conversion handles those offsets automatically when the selected zone observes them.
  • For recurring meetings that span a DST transition, re-run the conversion for each date to catch the seasonal offset change.
  • If you need a city or zone that is not in the dropdown yet, treat the result as a planning aid and double-check with a full calendar app.
Sources
  1. IANA Time Zone Database (tz database / Olson database)
  2. Time zone and offset standards — ITU-R TF.460-6 (Standard-frequency and time-signal emissions)

How daylight saving time affects conversions

Daylight saving time (DST) shifts clocks forward or backward by one hour on dates that vary by country and sometimes by region within a country. Because the transitions do not happen on the same weekend worldwide, two cities that are normally five hours apart can temporarily be four or six hours apart during the weeks when only one of them has changed clocks. The converter handles this automatically by looking up each zone's offset rules for the specific date you enter, but the result is only valid for that date. If you are scheduling a recurring event, re-run the conversion after every DST transition to catch any shift in the gap.

Planning recurring meetings across zones

When a weekly meeting involves participants in different hemispheres, the offset between them can change two to four times a year. Northern-hemisphere zones typically spring forward in March and fall back in November, while southern-hemisphere zones move in the opposite months. The safest approach is to anchor the meeting to one zone's clock and let the other participants adjust, or to re-run the converter at the start of each month. Some teams choose to hold the meeting at a UTC-fixed time so that neither side owns the shift, though that means both sides see their local time change with the seasons.

Time zone converter FAQs

Does this converter handle daylight saving time automatically?

Yes. The calculator uses named time zones and applies the offset rules that are in effect on the selected date.

What does a negative day shift mean?

A negative day shift (−1 day) means the converted time falls on the previous calendar date relative to the source date. This happens when the target offset is far enough behind that subtracting hours pushes the clock before midnight.

Can I convert times for regions with half-hour offsets?

Yes. Regions like India, parts of Australia, and New Zealand island territories use half-hour or quarter-hour offsets. The named-zone conversion handles them automatically when the selected zone uses them.

Why can the hour difference change during the year?

Because daylight saving time does not begin and end on the same dates everywhere. Two cities that are usually 5 hours apart can briefly be 4 hours apart or 6 hours apart during transition windows.

How do I convert in the other direction?

Simply swap the source and target time zones. The same UTC instant is being reformatted in the opposite direction, so the conversion is symmetric.

Written by Jan Křenek Founder and lead developer
Reviewed by DigitSum Methodology Review Formula verification and QA
Last updated Mar 10, 2026

Use this as an estimate and validate important decisions with a qualified professional.

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