About Date Format Converter
Parse any common date string — ISO 8601, RFC 2822, locale, custom strftime patterns, Unix epoch — and re-emit as any other format. Get relative output like "3 hours ago", or build a strftime pattern with the live cheatsheet. All parsing runs in your browser.
Why so many date formats?
Each ecosystem standardized on its own. ISO 8601 is unambiguous and machine-friendly. RFC 2822 is what email and HTTP use. Locale formats are what users expect. Unix timestamps are what databases store. strftime patterns are how you build custom output. Round-tripping between them is a daily task in any system that crosses ecosystem boundaries.
The formats that matter
| Format | Example | When it appears |
|---|---|---|
| ISO 8601 | 2024-01-15T14:30:00Z | APIs, JSON, logs |
| RFC 2822 | Mon, 15 Jan 2024 14:30:00 +0000 | Email, HTTP headers |
| Unix seconds | 1705329000 | DB timestamps, JWT exp |
| Unix milliseconds | 1705329000000 | JavaScript Date |
| US locale | 1/15/2024 2:30 PM | UI for US users |
| EU locale | 15/01/2024 14:30 | UI for EU users |
| Relative | 3 hours ago | UI everywhere |
| strftime | %Y-%m-%d %H:%M | Logs, custom formats |
Common workflows
Convert from your DB timestamp to a UI string. Paste the ISO value, pick locale + relative mode for the user-facing display.
Build a strftime pattern. Type the desired output, the cheatsheet reveals which tokens you need. Useful when porting code between Python’s datetime.strftime and Postgres to_char.
Verify a parsing error. API returns a date string your code rejects. Paste here. If we parse it cleanly, the bug is in your code; if we also fail, the API is sending garbage.
Translate between locale forms. US sends 1/15/2024, your German user sees 15.1.2024. Confirm the conversion before deploying.
Why a tool
Most languages have a strong date library — Python datetime, JS date-fns or Temporal, Java java.time. They are exhaustive but not always quick to test. A live tester gives you immediate feedback, and the strftime cheatsheet pins itself in muscle memory.
Frequently asked questions
What date formats does it recognize?
2024-01-15T14:30:00Z), RFC 2822 (Mon, 15 Jan 2024 14:30:00 +0000), locale forms (1/15/2024, 15.01.2024), Unix timestamps (s, ms, μs, ns), and human strings parsed via the browser's Date.parse.What is strftime?
%Y-%m-%d for ISO date, %H:%M:%S for time. C-derived, supported by every major language. The cheatsheet on the right lists every token.Why does my date show as the wrong day?
2024-01-15T00:00:00Z is midnight UTC, which can be Jan 14 evening in your local zone. Toggle UTC mode to see the absolute time.Can it output relative time?
Intl.RelativeTimeFormat.Does it handle locales?
en-US uses MM/DD/YYYY, en-GB uses DD/MM/YYYY, de-DE uses DD.MM.YYYY).Is the date sent anywhere?
Intl APIs. Your dates stay local.How do I format dates in Java, Swift, or JavaScript?
DateTimeFormatter.ofPattern("yyyy-MM-dd") (java.time) over the old thread-unsafe SimpleDateFormat. Swift/iOS: DateFormatter with a dateFormat string, or ISO8601DateFormatter for ISO. JavaScript: Intl.DateTimeFormat(locale, options).format(date), or date.toISOString() for ISO 8601. Note the pattern letters differ (Java yyyy vs strftime %Y) — build the output here to see which tokens you need.Can it convert ISO 8601, Julian, or locale date formats?
2024-045, or astronomical Julian Day Numbers), read the day-of-year via the strftime %j token; full astronomical JDN needs a dedicated calculation. Locale conversions (US MM/DD/YYYY ↔ EU DD/MM/YYYY ↔ Japanese YYYY年MM月DD日) are a locale toggle away.Related tools
Last updated: 2026-07-04