Date Format Converter Online — DD/MM/YYYY, MM/DD/YYYY, ISO 8601, Unix Timestamp

Enter a date in any format — the converter instantly shows it in all popular formats: from US MM/DD/YYYY and UK DD/MM/YYYY to ISO 8601, Unix timestamp and RFC 2822

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Reference dates — load into converter
Today

Current date according to your device

July 4, 1776

US Independence Day — a classic reference date often used to test historical date handling in applications

January 1, 2000

Start of the millennium — popular date for testing parsers and databases, and the center of Y2K concerns

January 1, 1970

Unix epoch — the zero point of Unix timestamps. All Unix timestamps are counted from this date at 00:00:00 UTC

February 29, 2000

Leap day — a frequent cause of bugs in programs that do not handle leap year logic correctly

December 31, 9999

Maximum date in many systems — useful for testing date overflow handling

Date formats explained — what they mean and where they are used
MM/DD/YYYY vs DD/MM/YYYY — why the US writes dates differently from the rest of the world

The United States uses MM/DD/YYYY — month first, then day, then year, separated by slashes. Example: 03/22/2026. The UK, Australia and most of the world use DD/MM/YYYY — day first, then month. This is the most common source of date confusion internationally: 03/04/2026 means March 4 in the US and April 3 in the UK. When sharing dates across countries, always use ISO 8601 (YYYY-MM-DD) to eliminate ambiguity. The US format is dominant in American software, Excel files set to US locale, and government documents.

ISO 8601 (YYYY-MM-DD) — the international standard and why it matters

ISO 8601 is the international standard for writing dates as YYYY-MM-DD (year-month-day). Example: 2026-03-22. Key advantages: it is unambiguous regardless of country or language, and it sorts correctly when treated as plain text — "2026-03-22" comes after "2025-12-31" alphabetically. This is the standard for SQL databases (DATE type), REST APIs, JSON, XML, log files, Git commits, and the HTML date input (type="date"). If you are a developer or work with data — always store dates in ISO 8601.

Unix timestamp — what it is and why developers use it

A Unix timestamp (also called POSIX time or epoch time) is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC. Example: 1742601600 = March 22, 2026 00:00:00 UTC. It is used across all operating systems, databases, programming languages, APIs and log files. Advantages: a single number that is language-neutral, timezone-independent (always UTC), and easy to use in date arithmetic — add 86400 to get tomorrow, subtract 3600 to get one hour ago. JavaScript uses milliseconds (Date.now() = seconds × 1000), so always divide JS timestamps by 1000 to get Unix seconds. Note: 32-bit systems face the Year 2038 problem.

DD/MM/YYYY — the British and international format explained

DD/MM/YYYY is the date format used in the United Kingdom, Australia, most of Europe, India, and the majority of the world. Day comes first, then month, then year. Example: 22/03/2026 = March 22, 2026. This format is intuitive for most people globally — it goes from the smallest unit (day) to the largest (year). It is the default in British English software, European government documents, and international business outside the US. When receiving files from non-US sources, assume DD/MM/YYYY unless stated otherwise.

Frequently asked questions about date formats
What is the difference between MM/DD/YYYY and DD/MM/YYYY?

The order of the day and month components. MM/DD/YYYY is the US format: month first, then day, then year. DD/MM/YYYY is the UK and international format: day first, then month, then year. The date 03/04/2026 means March 4 in the US and April 3 in the UK. If the format is unknown, use ISO 8601 (YYYY-MM-DD) — it is always unambiguous.

What is ISO 8601 and where is it used?

ISO 8601 is the international standard for writing dates (YYYY-MM-DD) and times (YYYY-MM-DDTHH:MM:SS). Example: 2026-03-22. It is used in: SQL databases (DATE type), REST APIs and JSON, HTML input[type="date"], log files, Git, XML, and HTML meta tags. The main advantage is that it is unambiguous across all countries and languages, and dates in this format sort correctly as plain strings.

How do I convert a Unix timestamp to a readable date?

Enter the number in the Unix timestamp field of the converter — you will immediately see the date in all formats. To convert manually: divide the timestamp by 86400 to get days since 1970-01-01. In JavaScript: new Date(timestamp * 1000).toISOString(). In PHP: date("Y-m-d", $timestamp). In Python: datetime.fromtimestamp(timestamp). Remember that JavaScript timestamps are in milliseconds, so divide by 1000 first.

How do I figure out the date format in an unknown file?

Enter a few dates into the converter and see which interpretation makes sense. Check the day value: if the first number is greater than 12 (e.g. 23/03/2026), it must be the day — the format is DD/MM/YYYY or DD.MM.YYYY. If both of the first two numbers are 12 or less, check the context or look for the year (usually four digits, appearing first or last). ISO 8601 (YYYY-MM-DD) always starts with a four-digit year.

What is RFC 2822 and where is it used?

RFC 2822 is the standard format for dates in email headers and RSS feeds. It looks like: Sun, 22 Mar 2026 14:30:00 +0200. It includes the weekday abbreviation, day, abbreviated English month name, year, time and UTC offset. In PHP: date("r") returns RFC 2822. In JavaScript: new Date().toUTCString() returns a similar format. You will commonly see it in raw email source headers and Atom/RSS feed timestamps.

Why does February 29 cause problems in software?

February has 29 days only in a leap year — a year divisible by 4, but not by 100, unless it is also divisible by 400. Programs that do not check this rule either crash or silently roll over to March 1. The year 2000 was a leap year (divisible by 400). The year 1900 was not. The converter validates leap year logic when you enter a February 29 date.

What is the Year 2038 problem with Unix timestamps?

The old 32-bit Unix timestamp will reach its maximum value of 2,147,483,647 on January 19, 2038 at 03:14:07 UTC. After that, a signed 32-bit integer overflows and becomes negative — programs still using that type will mishandle dates. Modern 64-bit systems and languages are not affected; their maximum timestamp extends billions of years into the future.

Which date format should I use in databases and APIs?

Always ISO 8601 (YYYY-MM-DD or YYYY-MM-DDTHH:MM:SSZ). Reasons: unambiguous regardless of language and locale, sorts correctly as a string, supported by all major databases (MySQL, PostgreSQL, SQLite), languages (JS, Python, PHP, Java) and standards (JSON Schema, OpenAPI). Unix timestamps stored as 64-bit integers are ideal for precise time values that need timezone awareness.

Date Format Converter — how to convert between DD/MM/YYYY, ISO 8601 and Unix timestamp

Date format mismatches are one of the most common causes of bugs in software, misunderstandings in documents, and data import failures. The reason is simple: different countries and systems use different conventions, and 03/04/2026 can mean both March 4 and April 3 — depending on who wrote it.

The US date format problem

The United States is one of the very few countries that puts the month before the day: MM/DD/YYYY. The rest of the world, including the UK, Australia, Europe, and most of Asia, uses either DD/MM/YYYY or the ISO standard YYYY-MM-DD. This single difference causes an enormous amount of confusion in international software, spreadsheets, and shared documents. If you receive a CSV from an American source and dates look wrong, try switching the month and day columns.

Why developers prefer ISO 8601

ISO 8601 (YYYY-MM-DD) solves the ambiguity problem completely. Since the year comes first, the format is impossible to misread. It also has a useful property: dates sort correctly as plain text strings, which means you can sort a column of ISO dates in a spreadsheet or database without any special handling. SQL, JSON, HTML, and most modern APIs default to YYYY-MM-DD for exactly this reason.

Unix timestamps and JavaScript milliseconds

A Unix timestamp is a single integer representing seconds since January 1, 1970 UTC. It is the universal language of date storage across operating systems, databases, and programming languages. One important gotcha: JavaScript's Date.now() and new Date().getTime() return milliseconds, not seconds. Always divide by 1000 when converting a JavaScript timestamp to a standard Unix timestamp for use in other systems. The converter handles both seconds and milliseconds automatically.

Common date format mistakes to avoid

The most frequent errors: importing a US-formatted CSV into European software (day and month swap silently), Excel auto-converting dates based on regional settings when opening files, APIs returning timestamps in milliseconds when seconds are expected, and databases storing dates as plain text strings without a fixed format. Always use a proper DATE or DATETIME column type, or store timestamps as 64-bit integers — never as strings.

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