Palindrome Date Finder (dates that read the same backwards, by date format)

Understanding the palindrome date finder — concept and principle

This tool lists the dates in a range of years that read the same forwards and backwards when written as eight digits, in year-first, month-first or day-first format. It is a fun calendar curiosity, popular for weddings, events and social media posts.

How it is calculated

• Write the date as eight digits in the chosen order (YYYYMMDD, MMDDYYYY or DDMMYYYY) and reverse it.
• Because the year fills four digits, the other four must be the year's digits reversed.
• For YYYYMMDD, the month is the last two year digits reversed and the day the first two reversed (2021 → 12, 02 → 2021-12-02).
• The date counts only if that month and day exist in the Gregorian calendar (29 February only in leap years).
• Each year has at most one palindrome date per format.

The principle

A palindrome reads the same in both directions. In an eight-digit date, the first four digits must mirror the last four. Once the year is fixed, the month and day are fixed too, so the search is simply: for each year, reverse its digits, split them into a month and a day, and check that they form a real date. Most years fail because the reversed digits give a month above 12 or a day that does not exist. That is why palindrome dates are rare and cluster in certain decades.

Worked example

Default inputs: YYYYMMDD format, years 2000 to 2100, viewed on Nov 10, 2026.

1. 2001 → reversed 1002 → month 10, day 02: 2001.10.02 (Tue, Oct 2, 2001), the first in the range.
2. 2010 → 01, 02: 2010.01.02; 2011 → 2011.11.02; 2020 → 2020.02.02; 2021 → 2021.12.02.
3. 2030 → 03, 02: 2030.03.02, the next one after today (Sat, Mar 2, 2030).
4. Total in the range = 12; the last is Sat, Sep 2, 2090.

How to read the result

The same calendar day can be a palindrome in one format and not in another: 2 February 2020 was a palindrome in all three. Choose the format used where you live: year-first in Korea, China and Japan; month-first in the US; day-first in much of Europe.

Common mistakes

• Including separators or two-digit years, which change the pattern.
• Expecting several palindrome dates in one year in the same format.
• Forgetting that 29 February exists only in leap years.
• Mixing formats when comparing lists.

Frequently asked questions

When is the next palindrome date?

In YYYYMMDD format, 2 March 2030 (2030-03-02).

How many palindrome dates are there this century?

In YYYYMMDD format, 12 between 2000 and 2100.

Why was 2 February 2020 special?

It was a palindrome in year-first, month-first and day-first formats.

Sources: Gregorian calendar rules (month lengths and leap years), e.g. ISO 8601-1:2019