## How to calculate a date based on specific weekday in a month

**Question:**

How to calculate the date of the third Monday of a given month?

### Answer:

Column B contains dates of the first date of a month, however, they are formatted as Month and year. This makes it possible to use the corresponding cell value in our formula.

**Array formula in cell C3**

To enter an array formula, type the formula in cell C3 then press and hold CTRL + SHIFT simultaneously, now press Enter once. Release all keys.

The formula bar now shows the formula with a beginning and ending curly bracket telling you that you entered the formula successfully.

Don't enter the curly brackets yourself, they appear automatically.

### Explaining array formula in cell C3

#### Step 1 - Create an array of numbers corresponding to days in month

The EOMONTH function calculates the last date in a given month, the DAY function then returns the day of that date.

ROW(INDIRECT( "$1:$"&DAY( EOMONTH(B3, 0))))-1)

becomes

ROW(INDIRECT( "$1:$"&DAY( EOMONTH(39814, 0))))-1)

becomes

ROW(INDIRECT( "$1:$"&DAY( 39844)))-1)

becomes

ROW(INDIRECT( "$1:$"&DAY( 39844)))-1)

becomes

ROW(INDIRECT("$1:$"&31))-1

The INDIRECT function converts a text string to a cell reference that an Excel function then can use.

ROW(INDIRECT($1:$31))-1

becomes

ROW($1:$31)-1

The ROW function then returns the row numbers of each cell in the cell reference.

ROW($1:$31)-1

becomes

{1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31} - 1

and returns {0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30}

#### Step 2 - Check if date is a Monday

The array in the step before is now going to be added to the first date in the given month.

WEEKDAY(B3 +ROW(INDIRECT( "$1:$"&DAY( EOMONTH(B3, 0))))-1)=2

becomes

WEEKDAY(B3 +{0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30})=2

becomes

WEEKDAY({39814; 39815; 39816; 39817; 39818; 39819; 39820; 39821; 39822; 39823; 39824; 39825; 39826; 39827; 39828; 39829; 39830; 39831; 39832; 39833; 39834; 39835; 39836; 39837; 39838; 39839; 39840; 39841; 39842; 39843; 39844})=2

It is worth mentioning that Excel treats dates as numbers. For example, number 1 is 1/1/1900 and 1/1/2000 is 36526. 1/2/2000 is 36527. The numbers you see above in the array are dates.

The WEEKDAY function converts the dates to their corresponding weekdays in numbers. 1 is Sunday and 7 is Saturday.

WEEKDAY({39814; 39815; 39816; 39817; 39818; 39819; 39820; 39821; 39822; 39823; 39824; 39825; 39826; 39827; 39828; 39829; 39830; 39831; 39832; 39833; 39834; 39835; 39836; 39837; 39838; 39839; 39840; 39841; 39842; 39843; 39844})=2

becomes

{5;6;7;1;2;3;4;5;6;7;1;2;3;4;5;6;7;1;2;3;4;5;6;7;1;2;3;4;5;6;7}=2

To identify Mondays in this array I will compare the numbers with 2.

{5;6;7;1;2;3;4;5;6;7;1;2;3;4;5;6;7;1;2;3;4;5;6;7;1;2;3;4;5;6;7}=2

returns the following boolean array:

{FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE}

Boolean values are TRUE and FALSE.

**Step 3 - Return corresponding date if Monday**

The IF function lets you evaluate a logical expression and if TRUE one thing happens and if FALSE another thing happens.

The logical expression in this example evaluates to TRUE if date is a Monday.

IF(WEEKDAY(B3+ROW(INDIRECT("$1:$"&DAY(EOMONTH(B3,0))))-1)=2,B3+ROW(INDIRECT("$1:$"&DAY(EOMONTH(B3,0))))-1,"")

becomes

IF({FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE},B3+ROW(INDIRECT("$1:$"&DAY(EOMONTH(B3,0))))-1,"")

If the value is TRUE then return the corresponding date. Since months have different number of days we must build an array that takes that into account.

It works just like the array we created in step 1.

IF({FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE},B3+ROW(INDIRECT("$1:$"&DAY(EOMONTH(B3,0))))-1,"")

becomes

IF({FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE; FALSE; TRUE; FALSE; FALSE; FALSE; FALSE; FALSE},{39814; 39815; 39816; 39817; 39818; 39819; 39820; 39821; 39822; 39823; 39824; 39825; 39826; 39827; 39828; 39829; 39830; 39831; 39832; 39833; 39834; 39835; 39836; 39837; 39838; 39839; 39840; 39841; 39842; 39843; 39844},"")

and returns

{""; ""; ""; ""; 39818; ""; ""; ""; ""; ""; ""; 39825; ""; ""; ""; ""; ""; ""; 39832; ""; ""; ""; ""; ""; ""; 39839; ""; ""; ""; ""; ""}

**Step 3 - Filter third Monday**

The SMALL function lets you return the third largest number in array because we are looking for the third Monday in a given month.

SMALL(IF(WEEKDAY(B3 +ROW(INDIRECT( "$1:$"&DAY( EOMONTH(B3, 0))))-1)=2, B3+ROW( INDIRECT("$1:$"&DAY( EOMONTH(B3, 0))))-1, ""), 3)

becomes

SMALL({""; ""; ""; ""; 39818; ""; ""; ""; ""; ""; ""; 39825; ""; ""; ""; ""; ""; ""; 39832; ""; ""; ""; ""; ""; ""; 39839; ""; ""; ""; ""; ""}, 3)

and returns 39832 in cell C3 which is the same as 1/19/2009 if formatted as a date in Excel.

### Download Excel *.xlsx file

Question: I am trying to create an excel spreadsheet that has a date range. Example: Cell A1 1/4/2009-1/10/2009 Cell B1 […]

Find latest date based on a condition

Table of contents Lookup a value and find max date How to enter an array formula Explaining array formula Download […]

Formula for matching a date within a date range

Table of contents Match a date when a date range is entered in a single cell Match a date when […]

The image above demonstrates an array formula in cell E4 that searches for the closest date in column A to the […]

Identify overlapping date ranges

The formula in cell F6 returns TRUE if the date range on the same row overlaps another date range in […]

Highlight records based on overlapping date ranges and a condition

adam asks: Hi, I have a situation where I want to count if this value is duplicate and if it […]

Lookup min max values within a date range

This article explains how to find the smallest and largest value using two conditions. In this case they are date […]

How to calculate overlapping time ranges

I found an old post that I think is interesting to write about today. Think of two overlapping ranges, it may be dates, […]

List all unique events in a month

Question: I have a table with four columns, Date, Name, Level, and outcome. The range is from row 3 to […]

Convert dates into date ranges

The array formula in cell D4 extracts the start dates for date ranges in cell range B3:B30, the array formula […]

### Leave a Reply

### How to comment

**How to add a formula to your comment**

<code>Insert your formula here.</code>

**Convert less than and larger than signs**

Use html character entities instead of less than and larger than signs.

< becomes < and > becomes >

**How to add VBA code to your comment**

[vb 1="vbnet" language=","]

Put your VBA code here.

[/vb]

**How to add a picture to your comment:**

Upload picture to postimage.org or imgur

Paste image link to your comment.

**Contact Oscar**

You can contact me through this contact form