Date & Time calculator

Time Zone Converter by City

Convert a dated local time between named IANA timezones with daylight saving rules, date rollover, and half-hour or quarter-hour offsets.

Timezone and daylight saving conversion

Convert an actual date and time, not a fixed UTC offset

Named timezones such as America/New_York and Europe/London carry daylight saving history and rules. A fixed label such as GMT-5 cannot describe every date in New York, so the selected date is part of the conversion.

The converter maps the source wall-clock time to an instant and then formats that instant in the destination timezone. This handles half-hour and quarter-hour zones as well as ordinary whole-hour differences.

Clock changes create edge cases. A local time can be skipped during a spring-forward transition or occur twice during a fall-back transition. Confirm critical travel, broadcast, release, and meeting times with the organizer when they fall near a clock change.

ReferenceValue or meaning
IndiaAsia/Kolkata uses UTC+05:30
NepalAsia/Kathmandu uses UTC+05:45
New YorkOffset changes with daylight saving time
Conversion basisSource local time -> UTC instant -> destination local time

Checks before using the result

  • Choose a named timezone that matches the city or region.
  • Enter the event date so daylight saving rules are applied correctly.
  • Include the calendar date when the converted time crosses midnight.
  • Verify ambiguous or skipped local times near DST transitions.

Sources and related tools

UTC to local timeStart from a UTC timestamp.Time duration calculatorCalculate elapsed time separately from timezone conversion.Business days calculatorCount weekdays across a date range.
FormulaSelected local time is mapped to an instant, then formatted in the target timezone

Formula

Timezone conversion

Selected local time is mapped to an instant, then formatted in the target timezone

12:00 in America/New_York converts using the daylight saving rule for the selected date.

SourcesThis calculator includes source notes, assumptions, and exclusions so the result is easier to verify before use.

Sources and assumptions

Source notes

This calculator includes source notes, assumptions, and exclusions so the result is easier to verify before use.

Effective year
Current rules
Last verified
2026-09-18

Use calculator results as estimates and verify important decisions with official sources.

Assumptions

    Not included

      FAQ8 common questions for this calculator.

      FAQs

      Does this include daylight saving rules?+

      Yes. Named IANA timezones such as America/New_York and Europe/London apply daylight saving rules for the selected date.

      Why does the date matter for timezone conversion?+

      Daylight saving offsets can change during the year, so the same clock time can have a different UTC offset on different dates.

      Does this support half-hour and quarter-hour timezones?+

      Yes. Named zones such as Asia/Kolkata and Asia/Kathmandu preserve their 30-minute or 45-minute offsets.

      Can a converted time fall on another date?+

      Yes. The destination may be on the previous or next calendar day, and the result includes that date.

      How does the Time Zone Converter calculate the result?+

      For the Time Zone Converter, it uses the Timezone conversion: Selected local time is mapped to an instant, then formatted in the target timezone. 12:00 in America/New_York converts using the daylight saving rule for the selected date.

      What information do I need to use the Time Zone Converter?+

      For the Time Zone Converter, enter the relevant dates, times, timezone, or calendar settings requested by the form. Exact dates matter because month lengths, leap years, and boundary days can change the result.

      How accurate is the Time Zone Converter?+

      Time Zone Converter is accurate for the values and assumptions entered on this page. It uses the Timezone conversion. Recheck the inputs before relying on the estimate.

      What should I check before using the Time Zone Converter result?+

      For the Time Zone Converter, check the date and time fields, date format, timezone, daylight-saving changes, inclusive or exclusive endpoints, and whether weekends or holidays should count.

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      Date & Time guide

      How to use the Time Zone Converter

      Convert a dated local time between named IANA timezones with daylight saving rules, date rollover, and half-hour or quarter-hour offsets. The page also explains the timezone conversion and shows a practical example: 12:00 in America/New_York converts using the daylight saving rule for the selected date.

      1. 1

        Enter your details

        Enter the source value, then choose the units or values you want to convert.

      2. 2

        Check the calculation

        Review the result alongside the timezone conversion: Selected local time is mapped to an instant, then formatted in the target timezone.

      3. 3

        Compare scenarios

        Change one or more inputs to see how they affect the time Zone Converter result before you use the estimate.