Date.DayOfWeekName - Date Function

Date.DayOfWeekName is a function in the Power Query M language that returns the name of the day of the week for a provided date. An optional culture may also be provided.

Compatible with: Power BI Service Power BI Desktop Excel Microsoft 365

Syntax

Date.DayOfWeekName(
   date as any,
   optional culture as nullable text,
) as nullable text

Argument	Attribute	Description
date
culture	optional	The culture argument enables the specification of a Culture code (e.g., “nl-NL” or “en-US”) to align transformations with local formatting conventions. If this argument is omitted, functions default to Culture.Current, which reflects the system’s regional settings.

Description

Date.DayOfWeekName provides the day of the week name for a specified date. It can also accept an optional culture argument for localization (e.g., “en-US”).

So what do we mean by culture here? Essentially, we’re referencing the standardized text representations of locales from the .NET framework. These culture codes perform a comparison in line with the rules of a given culture or locale. For an exhaustive list of culture codes, check the provided link.

Examples

The Date.DayOfWeekName function works with date, datetime, and datetimezone values.

Day of Week Name for a Date Value

When you apply the Date.DayOfWeekName function to a date value, it returns the name of the day of the week for that date. For example, to find the day of the week for June 15, 2024:

// Output: "Saturday"
Date.DayOfWeekName( #date( 2024, 6, 15 ) )

This expression returns “Saturday”, as June 15th, 2024 falls on a Saturday.

We can apply this to a table with a date column containing multiple date values. To get the name of the day of the week for each date, use Date.DayOfWeekName as follows:

Date.DayOfWeekName returns the name of the weekday in Power Query

Using Culture Codes

When writing the above code, my machine language is on English. The output is therefore an English day of the week name. If you want to change that to a different language, you can make use of an optional culture code.

For instance, the Dutch word for “Saturday” is “zaterdag”. To return the Dutch value, you can pass the “nl-NL” culture code:

// Output: "Zaterdag"
Date.DayOfWeekName( #date( 2024, 6, 15 ), "nl-NL" )

When applying the Dutch culture code to a range of dates, this look as follows:

Date.DayOfWeek supports culture codes for swapping language in Power Query

Day of Week Name for a DateTime Value

The function also supports datetime values. To find the day of the week for a datetime value of June 16th, 2024, 12:00 AM:

// Output: "Sunday"
Date.DayOfWeekName( #datetime( 2024, 6, 16, 0, 0, 0 ) )

This expression returns “Sunday”, as June 16th, 2024 falls on a Sunday.

Day of Week Name for a DateTimeZone Value

Similarly, applying the function to a datetimezone value returns the name of the day of the week for that datetimezone:

// Output: "Monday"
Date.DayOfWeekName( #datetimezone( 2024, 7, 15, 0, 0, 0, 1, 0 ) )

This expression returns “Monday”, as July 15th, 2024 falls on a Monday.

Learn more about Date.DayOfWeekName in the following articles:

Create Date Table with Dynamic Language in Power Query
Want your Date Table in Multiple Languages? This post explains how to make your calendar dynamic to support any language or culture. » Read more
Create Date Table or Calendar in Power Query M
Learn how to create a dynamic calendar table in Power Query’s M language. Build your custom columns and claim your free Date Table Script. » Read more

Other functions related to Date.DayOfWeekName are:

Date.MonthName

Contribute » | Contributors: Rick de Groot
Microsoft documentation: https://learn.microsoft.com/en-us/powerquery-m/date-dayofweekname