Date and Time Formats in LibreOffice Calc


In this tutorial, you will learn about Date and Time formats and how they are represented in LibreOffice Calc.

Let’s explain it with examples of a working problem.

Date and time formats in LibreOffice Calc

Date Formats

Open a blank Calc sheet and enter the items below – a date, a time, and a date-time.

"3/2/2018 6:00"

Once you enter, Calc will reformat them as below using default Calc formatting for each type.

Date Time Data
Date Time Data

Dates are stored as numbers in Calc, and each day represents a number counted from the date Dec 12, 1899.

However, you can change it from the menu Tools -> Options -> LibreOffice Calc -> Calculate. See below.


Right-click on the date at A1 cell and click Format Cells. The default format of the selected cell would open up as below. In the format list, you can use any format you want. The format code is displayed in the “format code” box in the below image.

Remember, the format changes based on the Language regional settings. For example, in India, the default date format is dd/mm/yy, whereas in the USA, it should be mm/dd/yy.

Format Cells-DD-MM-YY
Format Cells-DD-MM-YY

Convert the date to number

To convert the date to a number, simply choose Category=Number in the format cells window in Numbers tab, and you can see the numeric representation of the date.

For this example, 3/2/2018 is converted to the number 43134, which is nothing but the number of days that elapsed from Jan 0, 1900.

Format Cells-Date Numbers
Format Cells-Date Numbers

Time and Conversion

If you apply the same, i.e., format cells to numbers to the Time and Date Time, you can see the results below.

Converted to Number-All
Converted to Number-All

Time is represented on a scale of 0 to 1. So 6:00 AM is converted to .25, i.e. quarter of 24.

Custom Formatting of Date, Time

Calc provides a pre-defined set of date formats for general usage, which you can access from the Format list below (see at the bottom of this page under list format codes heading). However, if you want to customize your own format, you can use any of the codes below and create your own custom format.

To create a custom format, right-click any cell and open up the Format Cells dialog. In that dialog, start editing the Format Code (red arrow below). Once you modify it, you can see that a “user-defined” category is automatically created. Now, you can modify your format according to your needs. Refer to the format codes at the end of this article.

You can also rename the category = “User-defined” by clicking a small note icon (blue arrow below) and clicking the tick button to Add.

Format Cells-Custom Format
Format Cells-Custom Format

In this example, we have applied the custom date format, and it is applied to cell A1 below. It is worth noticing that though the representation is changed to “03/02/18Y”, the underlying value remains “03/02/2018”.

Custom Format Applied to a Date
Custom Format Applied to a Date

The same principle can be applied to Time formats as well.

Using text() function

LibreOffice features a powerful function =TEXT() which can also be used to convert dates. Syntax is follows:

text(Number, Format)

Number: Numeric value

Format: The text representing the format (as listed below table)

Now, let’s use the same example, i.e. 43134 as a number, to convert it to a date. To do that, you should use:

Using TEXT function to convert date
Using TEXT function to convert date

Likewise, you can play around with various format codes to get the desired result.

Various complex examples

Here are some of the number format codes (to add in the format cells window) and Text function codes for your easy understanding. It also includes the text function values with output:

The date used, for example, 1/25/2024 Thursday, has a value of 45316.

Number formattext function codesOutput
NNNNMMMM D, YYYY=TEXT(45316,”NNNNMMMM D, YYYY”)Thursday, January 25, 2024
NN, MMM D, YY=TEXT(45316,”NN, MMM D, YY”)Thu, Jan 25, 24
[NatNum12 D=ordinal-number]D MMM YYYY=TEXT(45316,”[NatNum12 D=ordinal-number]D MMM YYYY”)25th Jan 2024
[NatNum12 D=capitalize ordinal]D MMM YYYY=TEXT(45316,”[NatNum12 D=capitalize ordinal]D MMM YYYY”)Twenty-fifth Jan 2024
[NatNum12 D=capitalize ordinal]NNNN MMMM D=TEXT(45316,”[NatNum12 D=capitalize ordinal]NNNN MMMM D”)Thursday, January Twenty-fifth
[NatNum12 YYYY=title year,D=capitalize ordinal]D” of “MMMM, YYYY=TEXT(45316,'[NatNum12 YYYY=title year,D=capitalize ordinal]D” of “MMMM, YYYY’)Twenty-fifth of January, Two Thousand Twenty-Four
QQ YYYY=TEXT(45316,”QQ YYYY”)1st quarter 2024
“week” ww=TEXT(45316,'”week” ww’)week 4

List of Date Format Codes

Below are the format codes for dates that you can use in formatting cells.

FormatFormat Code
Month as 3.M
Month as 03.MM
Month as Jan-DecMMM
Month as January-DecemberMMMM
First letter of Name of MonthMMMMM
Day as 2D
Day as 02DD
Day as Sun-SatNN or DDD
Day as Sunday to SaturdayNNN or DDDD
Day followed by comma, as in “Sunday,”NNNN
Year as 00-99YY
Year as 1900-2078YYYY
Calendar weekWW
Quarterly as Q1 to Q4Q
Quarterly as 1st quarter to 4th quarterQQ
Era on the Japanese Gengou calendar, single character (possible values are: M, T, S, H)G
Era, abbreviationGG
Era, full nameGGG
Number of the year within an era, without a leading zero for single-digit yearsE
Number of the year within an era, with a leading zero for single-digit yearsEE or R
Era, full name and yearRR or GGGEE

If you change your locale of LibreOffice e.g. German, you need to use a different code as per below.

LocaleYearMonthDayHourDay Of WeekEra
English – en
and all not listed locales
German – deJ T   
Netherlands – nlJ  U  
French – frA J O 
Italian – itA G OX
Portuguese – ptA   O 
Spanish – esA   O 
Danish – da   T  
Norwegian – no, nb, nn   T  
Swedish – sv   T  
Finnish – fiVKPT  

List of Time format codes

To format time, use the format codes below:

FormatFormat Code
Hours as 0-23H
Hours as 00-23HH
Hours as 00 up to more than 23[HH]
Minutes as 0-59M
Minutes as 00-59MM
Minutes as 00 up to more than 59[MM]
Seconds as 0-59S
Seconds as 00-59SS
Seconds as 00 up to more than 59[SS]

Drop a comment if you have any questions/suggestions.


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How can I change the default date or time format in a spreadsheet or even globally in LibreOffice Calc?


Thank you very much !


you wrote “… day represent a number counted from the date Jan 0, 1900.”

That’s only correct, if you make a special setting in Tools -> Options -> LibreOffice Calc -> Calculate. The default is to count days since Dec 30, 1899 (which is day 0).

Wretched Vermin

I’m amazed that LibreOffice doesn’t support fractional seconds. Apparently this is too complicated for them.


For fractional seconds use “SS.00”


Probably I’m stupid, but I found all these replies incomprehensible. Here is how to convert a list of dates in the wrong format to the format you want.
Suppose you have a list of dates in an excel like:-

But, you want:
OCT 2019
JUN 2021
1. Copy all your list of dates into a text file and save it using a program like xed.
2. Cancel all the dates in your excel file
3. Right click over the column heading where you want to insert the list of dates.
4. From the dropdown menu select “Format Cells”.
5. Select the format you want. If the format you want doesn’t exist, you can create it as a user defined format. In my case, I selected Category Date and then Format Dec 1999 and the format code is MMM YYYY.
Then , click on the OK button.
6. Now, go back to your list of dates in your text file and select them all and copy them to your clipboard.
7. Then, click on cell 2 of the column in your excel where you want to put the dates. then EDIT then PASTE THEN ok.

Sidereal Libra

Thank you !!! You figure it out !!


How do change a date such as 1/1/20 to Friday January First?

Karim Hosein

Can we use PHP date types, such as,
1st, 2nd, 3rd, 4th, 5th,… 20th, 21st, 22nd, 23rd, 24th, 25th,… 30th, 31st?

In my region, long dates are written as such,
Tuesday, 3rd November 2020.

The best that I can see is
Tuesday, 3 November, 2020,
and that is not acceptable.

Matthew Andrews

How do I format cells to represent running times? For example, if a cell has 13:37, it’s because something happened for 13 hours and 37 minutes, not 1:37pm. Thanks.


How to format value 1.5 as “1 12” (1 day 12 hours)?
Another example 15.33333 as “15 8” (15 days 8 hours)?

Dave Rhodes

I have a list of bank transactions that are due, but how do I omit/change any Saturday or Sunday transactions to the following Monday?

Dave Rhodes

In my bank transactions, I would like any Sat or Sun dates to be moved to the monday. How would I format the column?

Dave Rhodes

Thank you.


I would like to know if there’s an easy way to convert dates that have 2021 into 2020. For instance, I am entering receipts from 2020 but the default (since it’s now 2021) is for my 03/25 to convert to 2021-03-25. Instead, I want 2020-03-25. I would love that to convert to 2020-03-25 without my having to write 2020/03/25 each time. Can I do that?

I thought one way might be to go ahead with them as 2021 and then switch to “General” format and subtract 365, then switch back to “Date.” But that seems clunky. Can’t I just have it autofill a chosen year if I’m entering the month and day?

Kai Hackemesser

If I have a cell containing a date, formated to the eye as YMD, and I want to use this formatted string in a formula, instead of its native value, how would I do that?

Bobby C

I have a column of start times and another of end times. In the third column I subtract the start from the end, and I want the display to be hours and minutes.

I used the custom format “H:MM” to get “1:43” with no leading zero, but I want a bit more control.

I want to add ‘h’ and ‘m’ to make clear what units are being shown, AND I want to exclude the hour altogether if it’s 0.

So it should display times like “1h 43m” or “17 m”.

Is that possible with a custom format string?

Bobby Cottle

So that requires a 4th column instead of just formatting the 3rd column cleverly. I suppose I could hide the 3rd column.

Not what I was hoping for, but it does solve my issue. Thanks!


This is lame. Many (most) parts of the world use YYYY MM DD as the default date and you can’t make this date the default format in LibreCalc. This is so 1990s.


Another Lame feature: Why calendar can not begin on 0. Jan 1900 as in excell. In such case you can directly display diference of dates in dd-hh:mm (00-12:33 for example). No one cares about not existing 0.1.1900 ancient day.

John Jeffrey

It would be useful if the same (or similar) techniques could be used to alter the format of dates in headers/footers, where there is no choice at the moment. Is this ever likely to be a feature?