How to use the ISLOGICAL function

What is the ISLOGICAL function?

The ISLOGICAL function returns TRUE if value is boolean.

1. Introduction

What is a Boolean value?

A Boolean value in Excel is a value that can only be TRUE or FALSE. It represents binary logic and is the result of a logical expression using logical operators or a result of a few Excel functions that I'll discuss below.

Mastering Boolean logic and logical expressions is key to manipulating data and controlling workflow in Excel.

What is binary logic?

Binary logic refers to values having one of two states, TRUE or FALSE. This allows Boolean algebra in Excel using logical operators.

What is a logical expression?

A logical expression is a statement that evaluates to TRUE or FALSE. For example:

=A1<4

These expressions use comparison operators to evaluate a condition and produce a Boolean result.

What are the comparison operators?

= - equal sign
< - less than sign
> - greater than sign

These operators let you build more operators like this:

<> - not equal to
<= - less than or equal to
>= - greater than or equal to

These comparison operators let you create logical expressions like: A2<>5 meaning if the value in cell A2 is not equal to 5, the result is either TRUE or FALSE.

What are the logical operators?

The main logical operators in Excel are:

• AND - Returns TRUE if all conditions are true
• OR - Returns TRUE if any condition is true
• NOT - Negates a logical expression
• XOR - Returns TRUE if only one condition is true

Other IS functions

Excel Function	Description
ISBLANK(value)	Returns TRUE if the value is empty, FALSE otherwise
ISERR(value)	Returns TRUE if the value is any error value except #N/A, FALSE otherwise
ISERROR(value)	Returns TRUE if the value is any error value, FALSE otherwise
ISEVEN(value)	Returns TRUE if the value is an even number, FALSE for odd numbers
ISFORMULA(reference)	Returns TRUE if the cell contains a formula, FALSE otherwise
ISLOGICAL(value)	Returns TRUE if the value is a logical value (TRUE/FALSE), FALSE otherwise
ISNA(value)	Returns TRUE if the value is the #N/A error, FALSE otherwise
ISNONTEXT(value)	Returns TRUE if the value is not text, FALSE if it is text
ISNUMBER(value)	Returns TRUE if the value is a number, FALSE otherwise
ISODD(value)	Returns TRUE if the value is an odd number, FALSE for even numbers

2. Syntax

ISLOGICAL(value)

value

Required. The value you want to check for a boolean value.

What is a cell reference?

A cell reference lets you "fetch" and use values in other cells in a formula.

There are two types of cell references:

• A1-style reference
• R1C1 reference

The A1-style reference is the default style in Excel, it names columns by letters from A to Z. After Z it starts over with AA, AB, and so on until XFD. Rows are numbered from 1 to 1048576, older Excel versions use less row numbers.

The R1C1-style uses row number and column number like: R1C1, R2C5 and R10C15. Rows are labeled R1, R2, R3 and so on, columns are labeled C1, C2, C3 etc.

The A1-style reference notation is the most common one, here are some examples:

A1 - single cell reference on the same worksheet
A1:D5 - reference to a cell range on the same worksheet
Budget!Z3 - a single cell reference to worksheet Budget
'Budget 2050'!A3 - a single cell reference to a worksheet containing a space character

There are two types of cell references:

• Relative cell references
• Absolute cell references

The examples above are all relative cell references, they change accordingly if a cell is copied and pasted to another cell which absolute cell references do not.

The $ dollar character lets you an absolute cell reference meaning you can lock a cell reference horizontally, vertically or both. Here is one example:

A$1 has a relative column reference but an absolute row reference, this means that the column letter may change if the cell is copied and pasted to cells in another column than A.

3. Example

The image shows the results of using the ISLOGICAL function in Excel for different input values. The ISLOGICAL function checks whether a given value is a logical value (TRUE or FALSE) and returns TRUE if it is, and FALSE if it's not.

Formula in cell C3:

Cell B3 contains text value "A" which is not a logical value. The formula in cell C3 returns FALSE.

Formula in cell C4:

Cell B4 contains numerical value 1 which is not a logical value.The formula in cell C4 returns FALSE.

Formula in cell C5:

Cell B5 contains boolean value TRUE which is a logical value.The formula in cell C5 returns TRUE.

Formula in cell C6:

Cell B6 contains value #DIV/0! which is an error value and not a boolean value. The formula in cell C6 returns FALSE.

Formula in cell C7:

Cell B7 contains value #N/A! which is an error value and not a boolean value. The formula in cell C7 returns FALSE.

Formula in cell C8:

Cell B8 contains value #VALUE! which is an error value and not a boolean value. The formula in cell C8 returns FALSE.

Formula in cell C9:

Cell B9 contains value #NAME! which is an error value and not a boolean value. The formula in cell C9 returns FALSE.

Formula in cell C10:

Cell B10 contains value FALSE which is a boolean value. The formula in cell C10 returns TRUE.

The ISLOGICAL function only returns TRUE for the boolean values TRUE and FALSE. For all other types of input (text, numbers, errors), it returns FALSE. The ISLOGICAL function is very useful to identify error values in arrays. Most Excel functions return the same error value, however, this function returns FALSE if it encounters an error.

4. ISLOGICAL function not working

Note that Excel interprets a number not equal to 0 (zero) as TRUE and 0 (zero) as FALSE, for example, in a IF function. However, the ISLOGICAL function does not.

 

 

Functions in 'Information' category

The ISLOGICAL function function is one of 19 functions in the 'Information' category.

Excel function categories

Excel categories

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