Does this calculator handle daylight saving time?

Yes. It uses the IANA timezone rules available in your runtime, so the applicable standard or daylight-saving offset is selected for the entered date.

Why can the converted date be different?

Time zones can be many hours apart. Converting the same instant can cross midnight and place the destination on the previous or following calendar date.

What happens to a local time skipped by a DST change?

The calculator displays a validation message when a local wall-clock time does not exist because clocks moved forward.

What is an IANA timezone?

It is a region-based identifier such as Asia/Kolkata or America/New_York whose rules include standard offsets and daylight-saving transitions.

Is this using a fixed manual offset table?

No. Conversion uses date-fns-tz and the runtime's IANA timezone data, avoiding inaccurate hard-coded offsets.

Date & Time Calculators

Time Zone Calculator

Convert a date and time between IANA time zones with DST support.

Free foreverRuns in your browserNo sign-up

Source date and time

Source dateSource time

Source timezone

Destination

Target timezone

Enter a source date and time to convert.

About the Time Zone Calculator

The Time Zone Calculator converts a source date and wall-clock time into the matching date and time in another IANA timezone. Source and destination panels keep both sides of the conversion clear.

The calculator uses the browser's IANA timezone database through date-fns-tz rather than a manual offset table. This allows historical and seasonal daylight-saving rules to be applied for supported zones.

Date rollover is handled automatically. A destination can fall on the previous or following calendar date, and the result displays a notice whenever its date differs from the source date.

Both zones show their active UTC offset and abbreviation for the selected instant. Calculations run locally in the browser, and entered values are not uploaded.

Key features

Source date, time and timezone inputs
IANA timezone destination selection
DST-aware conversion and offsets
Automatic previous or next date rollover
Quick source and destination zone swap

How to use

1Enter the source calendar date and local time.
2Choose the source timezone and destination timezone.
3Read the converted time, full date, abbreviation and UTC offset in the destination panel.
4Use Swap zones to reverse the source and destination timezone selections.

Frequently asked questions

Does this calculator handle daylight saving time?: Yes. It uses the IANA timezone rules available in your runtime, so the applicable standard or daylight-saving offset is selected for the entered date.
Why can the converted date be different?: Time zones can be many hours apart. Converting the same instant can cross midnight and place the destination on the previous or following calendar date.
What happens to a local time skipped by a DST change?: The calculator displays a validation message when a local wall-clock time does not exist because clocks moved forward.
What is an IANA timezone?: It is a region-based identifier such as Asia/Kolkata or America/New_York whose rules include standard offsets and daylight-saving transitions.
Is this using a fixed manual offset table?: No. Conversion uses date-fns-tz and the runtime's IANA timezone data, avoiding inaccurate hard-coded offsets.