How this works

Different systems and industries write dates in incompatible formats, which creates real-world friction whenever data crosses a boundary — between a US and European system, between a database and a display layer, between a developer's timestamp and a human-readable log entry. This converter takes a single date and outputs it in every common format simultaneously, so you can copy exactly what the downstream system expects.

The formats explained

ISO 8601 (YYYY-MM-DD)

The international standard, used in databases, APIs, file naming, and most technical contexts. Unambiguous regardless of locale. Sorts correctly alphabetically and lexicographically, which is why it's preferred in software systems. Example: 2025-03-14.

US format (M/D/YYYY)

Month before day, used throughout the United States. Ambiguous to international readers — 04/05/2025 means April 5th in the US but May 4th in most of the world. Example: 3/14/2025.

EU format (D/M/YYYY or D.M.YYYY)

Day before month, standard in most of Europe, Latin America, and many other regions. Example: 14/3/2025 or 14.03.2025.

Long written form

Fully spelled out — "March 14, 2025" or "14 March 2025". Used in formal documents, correspondence, and anywhere the date needs to be unambiguous to a human reader.

Unix timestamp

The number of seconds since midnight UTC on January 1, 1970. Used internally by almost all computing systems to store dates and times as a single integer. The same moment in time has one Unix timestamp regardless of time zone, making it useful for sorting and comparison. Example: 1741910400.

Julian date (YYDDD)

A two-digit year plus three-digit day-of-year. Day 001 is January 1st. Common in manufacturing, food production (especially expiration codes and batch numbers), aerospace, and some government systems. Example: March 14, 2025 = 25073.

Week number

The ISO 8601 week number (1–53), where week 1 is the week containing the first Thursday of January. Commonly used in logistics, manufacturing scheduling, and European business contexts.

Frequently asked

What's the difference between this and the astronomical Julian Date?

Astronomers use a Julian Date (JD) which is a continuous count of days since noon UTC on January 1, 4713 BC, expressed as a large decimal number (the current JD is around 2,460,000). The YYDDD format here is an ordinal date format commonly called "Julian date" in manufacturing and food packaging contexts — unrelated to the astronomical system despite the shared name.

Why would I need a Unix timestamp?

Unix timestamps are how almost all software stores dates internally. If you find a number like 1741910400 in a log file, database export, API response, or URL parameter, it's almost certainly a Unix timestamp. Paste it into the "convert from a Unix timestamp" field to decode it to a readable date.

Why does the date display differently in different countries?

Date format conventions evolved independently across cultures before international standards existed. The US retained month-first ordering from British colonial convention; most of Europe standardised on day-first; ISO 8601 introduced year-first as an unambiguous international standard. All three systems are in active use today, which is why dates like "05/06/07" remain genuinely ambiguous without additional context.

What is day-of-year used for?

The day-of-year (1–366) appears in Julian dates, some financial systems, and seasonal calculations. Knowing that a date is day 200 of the year tells you it falls in mid-July without needing to count months. It's also useful for measuring how far through the year a date falls as a simple percentage.