Date Format Converter
Convert a date or date-time between ISO, ISO with offset, US, European, long readable and Unix timestamp (seconds or milliseconds) formats. You choose the input format, and local or UTC output is clearly labelled.
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About the Date Format Converter
Date Format Converter takes one date or date-time and shows it in seven common formats at once: ISO date (YYYY-MM-DD), ISO date-time with a UTC offset, US date (MM/DD/YYYY), European date (DD/MM/YYYY), a long readable date, and Unix timestamps in seconds and milliseconds. Each result has its own copy button, and you can copy or download them all together.
You always choose the input format, because a value such as 01/02/2026 means 2 January in the US and 1 February in Europe — the tool never guesses. Date-only inputs can include an optional time and can be read as local time or UTC, and outputs can be shown in local time or UTC, clearly labelled with the browser’s time zone and offset. Impossible dates, invalid times, malformed timestamps and values outside years 1–9999 are rejected, and no external time service is used.
How to use
- Choose the format of the value you have.
- Type or paste the value, and add a time if you need one.
- Choose whether the input is local time or UTC, and how outputs should be shown.
- Click Convert to see all formats.
- Copy a single result, Copy All, or download the summary.
Key features
- Seven formats: ISO date, ISO with offset, US, European, long readable, Unix seconds and milliseconds.
- Explicit input format — ambiguous numeric dates are never guessed.
- Optional time and local/UTC interpretation.
- Local or UTC output, clearly labelled with time zone and offset.
- Validation of impossible dates, invalid times and malformed or out-of-range timestamps.
- Copy individual outputs, Copy All and Download Summary.
Best practices
- Prefer ISO 8601 (YYYY-MM-DD) when sharing dates internationally.
- Include a UTC offset with date-times so they are unambiguous.
- Check whether a timestamp is in seconds or milliseconds before converting.
- Use UTC output when comparing times from different places.
- Be careful around daylight-saving changes when converting local times.
Benefits
- One input, every common format.
- No more day/month mix-ups.
- Clear local versus UTC labelling.
- Private: runs in your browser without any time service.
Frequently asked questions
Why do I have to choose the input format?
Numeric dates are ambiguous: 01/02/2026 is 2 January in US format and 1 February in European format. Choosing the format means the tool never guesses wrongly.
What is the difference between local time and UTC?
Local time uses the time zone and daylight-saving rules of this browser. UTC (Coordinated Universal Time) is the same everywhere and has no daylight saving. The outputs say which one is shown.
What is a Unix timestamp?
The number of seconds (or milliseconds) since 1 January 1970 00:00:00 UTC. It is the same in every time zone. Values before 1970 are negative.
What happens if a local time does not exist?
On the day clocks go forward, some local times are skipped. If you enter one, the tool warns you and shows the time the browser used instead.
Which long date formats can I enter?
Formats such as “1 November 2026”, “November 1, 2026” or “Sunday, 1 November 2026”, using English month names (full or three-letter). If you include a weekday, it must match the date.
What range of dates is supported?
Years 1 to 9999 in the proleptic Gregorian calendar. Values outside this range, impossible dates such as 31 April, and malformed timestamps are rejected with a clear message.