Date Format Converter
Convert any date string between ISO 8601, Unix timestamp, RFC 2822, and 10+ other formats.
이 도구에 대해
The Date Format Converter parses a date string in virtually any common format and re-displays it in over ten standard representations simultaneously. Paste an ISO 8601 datetime, a US-style date (MM/DD/YYYY), a European date (DD/MM/YYYY), a Unix timestamp (seconds or milliseconds), an RFC 2822 email date, or a casual natural-language date — the tool auto-detects the format and converts it on the fly. Outputs include ISO 8601, RFC 2822, RFC 3339, Unix seconds, Unix milliseconds, UTC string, locale date/time strings, relative time (e.g. '3 days ago'), day of week, and Julian Day Number. Click any output row to copy that value to your clipboard.
사용 방법
- 1 Type or paste any date string into the input field.
- 2 The tool auto-detects the format and parses the date.
- 3 Scroll through the output table to see the date in all formats.
- 4 Click any row to copy that formatted value to your clipboard.
- 5 Use the Now button to load the current date and time.
Why date formats are such a mess
The same instant in time can be written dozens of ways, and several of them look identical while meaning different things. The string 03/04/2024 is March 4th in the United States and April 3rd almost everywhere else. Machines, meanwhile, prefer counting seconds since a fixed origin. This tool takes a date written in any common human or machine format, figures out what you meant, and renders it in more than a dozen standard representations at once so you can copy whichever the next system expects. Crucially, it normalizes everything to UTC, so the outputs are unambiguous.
How the input is detected
The tool inspects your text with a series of pattern checks, in order, and labels what it found:
| If the input looks like… | It is read as |
|---|---|
9–10 digits (e.g. 1721036400) | Unix timestamp in seconds |
12–13 digits (e.g. 1721036400000) | Unix timestamp in milliseconds |
MM/DD/YYYY (slashes) | US date |
DD.MM.YYYY (dots) | European date |
YYYY-MM-DD… | ISO 8601 |
| anything else | Handed to the browser's own parser |
The detected format is shown above the results, so you can immediately confirm the tool interpreted an ambiguous string the way you intended.
A worked example
Enter the Unix timestamp 1721036400. The tool sees ten digits, multiplies by 1000 to get milliseconds, and constructs the date — Monday, 15 July 2024, 07:00:00 UTC. It then produces, among others: ISO 8601 2024-07-15T07:00:00.000Z, RFC 2822 Mon, 15 Jul 2024 07:00:00 +0000, Unix seconds 1721036400, US date 7/15/2024, EU date 15.07.2024, the long form "Monday, July 15, 2024," the ISO week number, the day of the week, a relative phrase like "11 months ago," and even the Julian Day Number (a continuous day count used in astronomy, computed as floor(ms / 86,400,000) + 2,440,588). Click any value to copy it.
The output formats and where they are used
- ISO 8601 / RFC 3339. The web's lingua franca for timestamps — what you store in databases and send in JSON APIs.
- RFC 2822. The format email headers and HTTP dates historically use.
- Unix seconds and milliseconds. What most programming languages and logs work with internally; note that JavaScript uses milliseconds while many backends use seconds — a frequent source of "my date is 1,000× off" bugs.
- Relative time. "3 days ago" / "in 2 hours," computed against the current moment, the way social feeds display dates.
- ISO week number. Useful for reporting periods; it follows the ISO rule where weeks start on Monday.
The UTC detail you must not miss
Every output is rendered in UTC, not your local time zone. This is deliberate — it makes results unambiguous and reproducible — but it means a date shown here may differ by several hours from your wall clock. If you enter a date without a time zone, such as 2024-07-15, the browser interprets it as midnight UTC. If you need a specific zone, include an offset in your input (for example 2024-07-15T10:30:00+09:00) and the tool will convert it correctly to UTC before displaying.
Common mistakes
- Ambiguous slash dates. The tool treats slash dates as US
MM/DD/YYYY. If you meant day-first, use dot format (DD.MM.YYYY) or ISO to be safe — always check the "Detected" label. - Seconds vs milliseconds. Paste a 13-digit number when you meant seconds and you will land in the far future; the tool distinguishes them by digit count, so trust the detected label over your assumption.
- Expecting local time. Remember the outputs are UTC. The "ISO time only" value ends in
Zprecisely to flag that. - Two-digit years and odd separators. Stick to four-digit years; unusual formats fall through to the browser parser, which may guess differently across browsers.
All parsing and formatting happen in your browser with the native Date object — no date you enter is sent anywhere.