Tools

Convert dates and time zones

Convert one date-time per line between ISO 8601, Unix time and local time in named time zones. Daylight-saving gaps and repeats are reported.

Process locally

Files stay in this browser session. Closing or clearing releases them.

Import recipe

Add text

Type or paste the text to process

Adjust settings

Optional: Input format, Source time zone, Output format and more

Input formatSource time zoneIANA, e.g. Europe/BerlinOutput formatTarget time zoneIANA, e.g. America/New_YorkRepeated local times

Run

Processes in this browser; cancel at any time

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About this tool

Convert dates and times between ISO 8601, Unix time and local time in any IANA time zone. Use it to read a Unix timestamp from a log, to turn a UTC time from an API into Beijing time, or to work out a meeting time across time zones.

Paste one value per line, up to 10,000 lines, and every line is converted with the same settings. Times that daylight saving skips or repeats are reported instead of being quietly adjusted. Everything runs in your browser without uploading.

How to use it

Type or paste one date-time per line, or select Use example.
Set the “Input format”: “ISO 8601 with offset”, “Unix seconds”, “Unix milliseconds” or a local time. For a local time, also enter the “Source time zone” as an IANA name such as Asia/Shanghai.
Choose the “Output format” and the “Target time zone”, for example America/New_York. The target time zone applies to local time and ISO 8601 with offset.
Select Run, preview the converted times line by line in the original order, and download them as a text file.

Formats and limits

Input: Text
Output: Plain text
Size limit: 1 MB
Settings: Input format (ISO 8601 with offset, Unix seconds, Unix milliseconds, Local "YYYY-MM-DD HH:mm[:ss]"); Source time zone; Output format (ISO 8601 with offset, ISO 8601 in UTC, Unix seconds, Unix milliseconds, Local "YYYY-MM-DD HH:mm:ss"); Target time zone; Repeated local times (Stop and report, Use the earlier time, Use the later time)
Privacy: Files stay in the current browser session. No file bytes are uploaded.
Price: Free, no sign-up

Common questions

Is my timestamp in seconds or milliseconds?

A current Unix time has 10 digits in seconds and 13 in milliseconds. With “Unix seconds”, a 13-digit value is rejected as unreadable; with “Unix milliseconds”, a 10-digit value is accepted but lands in January 1970, which means you should switch to seconds.

Why is an ISO 8601 time without Z or an offset rejected?

Without Z or an offset such as +08:00, it is not clear which moment is meant. Set the “Input format” to local time and fill in the “Source time zone”, which is used only for that format.

What happens around daylight-saving changes?

A local time that is skipped, such as 2026-03-08 02:30 in America/New_York, stops the run with an error. A time that occurs twice, such as 2026-11-01 01:30 there, follows “Repeated local times”: “Stop and report”, “Use the earlier time” or “Use the later time”.

Why is the time wrong when I enter CST?

Abbreviations like CST are ambiguous, and a browser can read CST as US Central Time (America/Chicago) rather than China Standard Time. Use a full IANA name such as Asia/Shanghai.

What if one line cannot be read?

The whole run stops, and the message lists up to five of the unreadable lines with their line numbers, so you can fix them and run again. Empty lines stay empty in the result.

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