Convert US dates to UK dates in a spreadsheet

A file from a US system writes 10/07/2026 for 7 October; a UK reader sees 10 July. Mix in dates typed by hand and the column becomes unusable. Klerio's free cleaner puts every date in one format, and asks you how your file writes dates instead of guessing.

Clean a file free

How it works

Open the free cleaner and drop in your CSV or Excel file.
Tick 'Dates' and choose the format you want: 07/10/2026 (UK), 10/07/2026 (US) or 2026-10-07.
If some dates could be read either way, Klerio shows an example and asks whether your file is day first or month first.
Check the list of changes, then download.

Why Klerio

Never guesses: 04/05/2026 is left alone until you say whether it's 4 May or 5 April.
Mixed formats fixed: 7 Oct 2026, 2026/10/07 and 07-10-2026 all end up in the format you chose.
Only date columns: Columns are recognised as dates from their contents, so codes and IDs aren't touched.
Free and private: No sign-up, and your file is worked on in your browser.

Common questions

Can't Excel do this?

When Excel opens a CSV it often reads US dates the wrong way round and leaves the rest as text. Klerio reads the file exactly as written, before Excel changes anything.

Which format should I choose?

07/10/2026 for people in the UK; 2026-10-07 for importing into another system, because no system misreads it.

Is it free?

Yes, the free cleaner needs no account.