excel switching yyyy-mm-dd positions

[lezawang]

Hi
My computer time is formatted as dd/mm/yyyy
if I enter a date like 19/04/2021 excel will move it to the right hand side. which is good
if I enter a date like 04/19/2021 excel will keep that to the left hand side (not date) which is good too and correct

When I enter 2021/04/19 excel will change the order and make it 19/04/2021 and move it to the right. Why is that? I thought it should not accept it as a date since my computer format dd/mm/yyyy
There is no day 2021?

Thank you very much.

 

[diddi]

excel interprets this as a date and formats according to your regional setting. the second example (4/19) is not a date so it is not reformatted

 

[lezawang]

Thanks for your reply. Why excel interprets the 3rd case as a date but not the second date. Both are not following the same format of the computer? Thanks again.

 

[MARK858]

Because Excel accepts the International date format ISO 8601, which is yyyy-mm-dd.

ISO 8601 - Wikipedia

en.m.wikipedia.org