How does this tool know if my timestamp is seconds or milliseconds?

It counts the digits: a value of 13 digits or more is treated as milliseconds since the Unix epoch, anything with fewer digits is treated as seconds, which matches typical output from most programming languages.

What is a Unix timestamp?

It is the number of seconds, or milliseconds, that have elapsed since 00:00:00 UTC on January 1, 1970, used widely in APIs, logs and databases because it is a single unambiguous number regardless of time zone.

Can I paste an ISO 8601 date instead of a number?

Yes, any string JavaScript's Date constructor can parse works, including ISO 8601 timestamps with a time zone offset, and the tool converts it the same way as a numeric Unix timestamp.

Does the Relative time value update automatically?

Yes, the current time it compares against ticks every second, so a Relative value like 'in 2 minutes' or '5 seconds ago' keeps counting without needing to re-enter the timestamp.

Timestamp & Time Zone Converter

Convert Unix timestamps and dates across UTC, local and world time zones, locally.

Local, Runs entirely in your browser, your data never leaves your device.

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Convert one timestamp into every format and time zone you need

A Unix timestamp or an ISO string from an API response is only useful once you know what it means in your own time zone, and pasting the same value into ten different converters gets old fast. This tool accepts a Unix timestamp, in either seconds or milliseconds, or any date string JavaScript's Date can parse, and shows it as ISO 8601, UTC, your local time, a relative phrase like '3 hours ago', and the equivalent time in ten common IANA time zones at once. Parsing and formatting both run locally.

How to use the Timestamp & Time Zone Converter

Type a Unix timestamp or a date string into the input field, or click Now to fill in the current time.
Check whether the value was read as seconds or milliseconds; 13 or more digits are treated as milliseconds.
Read the ISO 8601, UTC, Local and Relative rows for the parsed moment.
Scroll the Time zones list to see the same moment formatted for cities including New York, London, Istanbul, Kolkata, Shanghai and Tokyo.
Hover any row and use its copy button to grab just that value.

Digit count decides the unit: a numeric input of 13 or more digits is read as milliseconds since the epoch, anything shorter is read as seconds, which matches how most languages emit Date.now() versus time().

Non-numeric input is parsed with JavaScript's Date constructor, so ISO 8601 strings and most RFC-style date strings work, but ambiguous formats such as MM/DD versus DD/MM can be read differently than you intend.

Frequently asked questions

How does this tool know if my timestamp is seconds or milliseconds?: It counts the digits: a value of 13 digits or more is treated as milliseconds since the Unix epoch, anything with fewer digits is treated as seconds, which matches typical output from most programming languages.
What is a Unix timestamp?: It is the number of seconds, or milliseconds, that have elapsed since 00:00:00 UTC on January 1, 1970, used widely in APIs, logs and databases because it is a single unambiguous number regardless of time zone.
Can I paste an ISO 8601 date instead of a number?: Yes, any string JavaScript's Date constructor can parse works, including ISO 8601 timestamps with a time zone offset, and the tool converts it the same way as a numeric Unix timestamp.
Does the Relative time value update automatically?: Yes, the current time it compares against ticks every second, so a Relative value like 'in 2 minutes' or '5 seconds ago' keeps counting without needing to re-enter the timestamp.