How to Mask All but the Last Four Digits in Excel

Hide sensitive numbers behind asterisks while keeping the last four digits — for account numbers, cards and email addresses.

You will learn to

• Mask a variable-length number keeping the last four digits
• Mask a card number in a fixed display format
• Mask the local part of an email address

How it works

To share a report without exposing full account numbers, show only the last four characters: =REPT("*",LEN(B2)-4)&RIGHT(B2,4). LEN-4 works out how many characters to hide, REPT draws that many asterisks, and RIGHT keeps the visible tail — so the masked value is the same length as the original.

For card numbers a fixed pattern is clearer: ="**** **** **** "&RIGHT(C2,4). Email addresses can be masked too: keep the first letter, hide the rest of the name and keep the domain. Remember that masking with formulas only hides the value in that column — delete or protect the original column before sharing.

=REPT("*",LEN(B2)-4)&RIGHT(B2,4)