Date Format Converter

Paste a date in almost any written form and see it in ISO 8601, RFC 2822, RFC 3339, US and European numeric styles, long English text, ISO week and ordinal notation and your own custom pattern. Dates such as 03/04/2025 that could mean two different days are flagged instead of being guessed silently.

Date & Time Converters Runs in your browser

Convert a Date Format

JavaScript is required. This tool runs in your browser, so please enable JavaScript to use it. The instructions below are still available.

Date to convertISO 8601, RFC 2822, 15/03/2024, March 15, 2024, 15 Mar 2024 14:30 …

Order of numeric dates

Custom patternTokens: YYYY YY MMMM MMM MM M DD D dddd ddd HH H hh h mm ss A Z; text in [brackets] is kept.

How to Use the Date Format

Type or paste the date, with or without a time and UTC offset.
If it is purely numeric (such as 04/05/2024), choose the Order of numeric dates.
Read every format in the table, and adjust the Custom pattern if you need a specific layout.
Use Copy ISO 8601 or the table to copy the format you need.

About This Tool

Developers handling API and database dates, data analysts cleaning spreadsheets from different countries, writers and editors following a style guide, and anyone confused by day-first versus month-first dates.

Input: A date (and optional time) · Output: The date in many formats.

Features and Limitations

Features

Understands ISO 8601 (including week and ordinal dates on output), RFC 2822 email dates, numeric dates with / . or - and dates with month names.
Refuses impossible dates such as 31 April and flags ambiguous ones instead of guessing.
Keeps the calendar date you typed: no hidden time-zone shift.
Custom pattern with common tokens, plus locale renderings from your browser's Intl API.

Limitations

Two-digit years are read as 1950–2049.
Only the Gregorian calendar and English month names are recognised in input.
When no UTC offset is given, formats that need one (RFC 2822, Unix time) assume UTC and say so.
Results are computed in your browser; nothing you enter is sent to a server.

Example

2024-03-15T14:30:00+05:30 becomes Fri, 15 Mar 2024 14:30:00 +0530 (RFC 2822), 03/15/2024 (US), 15/03/2024 (UK), 2024-W11-5 (ISO week) and 2024-075 (ordinal).

Frequently Asked Questions

Why does 03/04/2025 need a setting?

In the US it means March 4; in the UK, India and most of Europe it means 3 April. The converter will not guess when both readings are valid. Choose the order, or write the date as 2025-04-03 to avoid the problem.

What is ISO 8601?

The international standard for writing dates as year-month-day, such as 2024-03-15, optionally followed by a time and offset (T14:30:00+05:30). It sorts correctly as text and is unambiguous.

What is RFC 2822?

The date format used in email headers, such as Fri, 15 Mar 2024 14:30:00 +0530. RFC 3339 is a stricter profile of ISO 8601 used by internet protocols and APIs.

What is an ISO week date?

It identifies a day by year, week number and weekday, such as 2024-W11-5 for Friday of week 11. ISO weeks start on Monday, and week 1 is the week containing the first Thursday of the year.