Donaldson R F Date Format Converter
Turn 03/04/2026 into 2026-04-03 — or any other date format — without guessing which number is the month.
All formats for the first date
Why date formats cause mix-ups
The date 03/04/2026 is 3 April in most of the world but 4 March in the United States — so you must say which order your dates use before converting. The international standard ISO 8601 (YYYY-MM-DD) puts the largest unit first, sorts correctly as text and can't be misread, which is why it is preferred for files, databases and APIs. Dates are checked against the real calendar (29 February only exists in leap years), and years must have four digits. Custom patterns use YYYY, YY, MMMM (December), MMM (Dec), MM, M, DD, D, dddd (Thursday) and ddd (Thu). Everything runs in your browser.