LUHN_CHECK

Checks if a value passes the Luhn (MOD 10) checksum

Formula definition
Download 
=LET(
    s, REGEXREPLACE(TRIM(check_value), "[^0-9]", ""),
    n, LEN(s),
    IF(
      n<2,
      FALSE,
      LET(
        pos, SEQUENCE(n),
        adjusted, MAP(pos, LAMBDA(p,
          LET(
            d, VALUE(MID(s, p, 1)),
            fr, n - p + 1,
            x, IF(MOD(fr, 2)=0, d*2, d),
            IF(x>9, x-9, x)
          )
        )),
        MOD(SUM(adjusted), 10)=0
      )
    )
  )

Function details

This function checks whether a text value passes the Luhn algorithm, also known as the MOD 10 checksum. This is useful for quickly catching typos in numeric identifiers that use Luhn, such as payment card numbers or other ID strings that include a check digit. For example, if cell D2 contains 4242 4242 4242 4242, then =LUHN_CHECK(D2) returns TRUE, while if cell D3 contains 4242 4242 4242 4243, then it returns FALSE.

Use the inputs below to create LUHN_CHECK as a reusable custom function in Google Sheets.

Learn how to add custom functions to Google Sheets
Function name

LUHN_CHECK

Function description

Checks if a value passes the Luhn (MOD 10) checksum

Formula definition

=LET( s, REGEXREPLACE(TRIM(check_value), "[^0-9]", ""), n, LEN(s), IF( n<2, FALSE, LET( pos, SEQUENCE(n), adjusted, MAP(pos, LAMBDA(p, LET( d, VALUE(MID(s, p, 1)), fr, n - p + 1, x, IF(MOD(fr, 2)=0, d*2, d), IF(x>9, x-9, x) ) )), MOD(SUM(adjusted), 10)=0 ) ) )

Argument placeholder

check_value

Argument details

Argument description (check_value)

Text value to validate with the Luhn checksum

Argument example (check_value)

A1

Related functions

Other functions in the same category: Data Validation

IS_VALID_CC

Checks if a card number passes the Luhn (MOD 10) checksum

Data Validation

IS_VALID_EMAIL

Checks whether a text value matches a basic email address format

Data Validation

IS_VALID_IPV4

Checks whether a text value is a valid IPv4 address

Data Validation

IS_VALID_IPV6

Checks whether a text value is a valid IPv6 address

Data Validation

IS_VALID_ISBN10

Checks whether a text value is a valid ISBN-10

Data Validation

IS_VALID_ISBN13

Checks whether a text value is a valid ISBN-13

Data Validation

What is a named function in Google Sheets?

Named functions enable the creation of custom, reusable formulas that mimic built-in functions, streamlining calculations and data manipulations. These functions simplify complex formulas, making spreadsheets more readable and less prone to errors. By encapsulating intricate logic within a single function call, they enhance consistency across your data. Utilizing named functions reduces the need to write lengthy formulas repeatedly, thereby improving workflow efficiency and productivity in data analysis and management.

How to add custom functions to Google Sheets

Quick & dirty method

Download and import — fastest way to add the function but does not include argument descriptions and examples

Follow these simple steps to download and import a function into your spreadsheet. This method is the quickest and easiest way to add the named function to your Google Sheets document, but will not include the argument description and examples.

  1. 1
    Download the formula: Click on the download button next to the function to download a file with the formula.
  2. 2
    Open Google Sheets: Open your Google Sheets document, from the top menu select Data > Named functions. Click Import function.
  3. 3
    Import the function: Select Upload and select the file you downloaded with the function. Click Import all or select which function(s) to import and click Import.

Once added, the function will be ready to use in your document like any other built-in function. Simply type the function name and provide the required inputs to use it in your calculations.

Manual & detailed method

Copy and paste — copy and paste each property one at a time

Follow these simple steps to integrate a custom named function into your spreadsheet:

  1. 1
    Open Google Sheets: Open your Google Sheets document, from the top menu select Data > Named functions. Click Add new function.
  2. 2
    Enter the function details: For each input copy and paste the information for the function.
    • Copy the name of the function to the Function name input.
    • Copy the description of the function to the Function description input.
    • Copy each placeholder one at a time into the Argument placeholders input, if there are any placeholders.
    • Copy the formula of the function to the Formula definition input.
    Click Next.
  3. 3
    Add additional details: Optionally you can add a description and example for the placeholders.
  4. 4
    Save the function: Click Create to add the function to your document.

Once added, the function will be ready to use in your document like any other built-in function. Simply type the function name and provide the required inputs to use it in your calculations.

Tips

  • If you import a named function that has the same name as a named function that already exists in your active file, the imported one will override the existing named function.
  • If the named function that you selected to import depends on another named function, like formula definition, Google Sheets will warn you about that dependency and highlight the dependent functions.
  • If the named function that you selected to import uses a formula that interacts with an external source, like IMAGE, Google Sheets will warn you about that interaction.