Short answer: yyyyMMdd means four-digit year + two-digit month + two-digit day. March 5, 2026 becomes 20260305. Pad single-digit months and days with a leading zero and leave out slashes and hyphens.
What each part means
| Symbol | Meaning | Digits | March 5, 2026 |
|---|---|---|---|
| yyyy | Year | 4 | 2026 |
| MM | Month (01–12) | 2 | 03 |
| dd | Day (01–31) | 2 | 05 |
| yyyyMMdd | 20260305 | ||
The letters stand for year, month and day, and the number of letters tells you the number of digits. The format is also called YYYYMMDD, or the ISO 8601 "basic" date format.
When a form asks for YYYYMMDD
- Type exactly eight digits.
- Pad with zeros: March 5 → 0305, not 35.
- No separators: 20260305, not 2026/03/05 or 2026-03-05.
- Year first, always: a US birthday written 04/07/1990 (April 7) becomes 19900407.
Upper case vs lower case: yyyymmdd, YYYYMMDD, yyyyMMdd
In instructions written for people — forms, specs, emails — yyyymmdd, YYYYMMDD and yyyyMMdd all mean the same eight-digit date. You do not need to worry about the case.
In date-format strings in code, the case changes the meaning:
| Environment | Correct pattern | Common mistake |
|---|---|---|
| Java (SimpleDateFormat / DateTimeFormatter) | yyyyMMdd | mm is minutes, DD is day of year and YYYY is the week-based year — using YYYY shows the wrong year for a few days around New Year |
| C# (.NET) | yyyyMMdd | mm is minutes; use DateTime.Now.ToString("yyyyMMdd") |
| Python | %Y%m%d | Different syntax; %M is minutes |
| Excel (TEXT function, number formats) | yyyymmdd | Not case-sensitive, but mm next to h or s is read as minutes |
That is why this site writes "yyyyMMdd": capital MM for month, as in most programming languages.
yyyyMMdd vs yyyy-MM-dd, MM/dd/yyyy and yyMMdd
| Format | Example | Notes |
|---|---|---|
| yyyyMMdd | 20260305 | ISO 8601 basic format. Safe in file names; name order equals date order |
| yyyy-MM-dd | 2026-03-05 | ISO 8601 extended format. Easy to read; standard for data exchange |
| MM/dd/yyyy | 03/05/2026 | US style. Read as 3 May in day-first countries; slashes are not allowed in Windows file names |
| dd/MM/yyyy | 05/03/2026 | UK/European style. Read as May 3 in the US |
| yyMMdd | 260305 | Short, but the two-digit year is easy to confuse with other numbers |
More on the standard behind it: ISO 8601 explained. On writing dates in sentences: US vs UK date format.
More on related formats: yymmdd (6 digits), yyyy/mm/dd vs yyyy-mm-dd vs yyyymmdd and date of birth in yyyymmdd.
Date and time: yyyyMMddHHmmss (14 digits). Day-first order: ddmmyyyy.
Converting yyyyMMdd in Excel
- Display a date as yyyymmdd: Format Cells → Custom →
yyyymmdd - Turn a date into text:
=TEXT(A1,"yyyymmdd") - Turn 20260305 back into a date:
=DATE(LEFT(A1,4),MID(A1,5,2),RIGHT(A1,2)), or Data → Text to Columns → Date: YMD
Why people use yyyyMMdd
For practical file-naming patterns, see Why yyyyMMdd is the best date format for file names.
Type it with one key
Typing eight digits by hand invites mistakes like 20260350. InsertDate is a Windows app that enters today's date in yyyyMMdd when you press the Insert key — in Excel, Word, Outlook, your browser and the File Explorer rename box.
Frequently Asked Questions
What is an example of the yyyyMMdd format?
March 5, 2026 is 20260305 and April 7, 1990 is 19900407: a four-digit year, two-digit month and two-digit day with no separators.
Is YYYYMMDD the same as yyyyMMdd?
In forms and documents, yes — both mean an eight-digit year-month-day date. In programming languages such as Java and C#, lower-case mm means minutes, so use capital MM for the month.
Is yyyyMMdd an ISO 8601 format?
Yes. ISO 8601 allows the basic format YYYYMMDD (20260305) as well as the extended format YYYY-MM-DD (2026-03-05).
How do I add the time?
Append hours, minutes and seconds: yyyyMMddHHmmss, for example 20260305143000. HH is the 24-hour clock, mm is minutes and ss is seconds.
Try InsertDate Free for 7 Days
Press Insert. Get today's date in yyyyMMdd. Works in almost any Windows app, including Excel, Word and Notepad, with no configuration. To type into an app running as administrator, run InsertDate as administrator too.
InsertDate is a Windows 10/11 app. Reading on a phone? Open this page on your PC to install it.