How to generate a random alphanumeric string with a formula in Excel (or Google Sheets or LibreOffice) - excel

Question

I'm trying to generate a random 8 character alphanumeric string in Excel (or Google Sheets or Libreoffice, which both have the same challenge) using a formula. I'd like to get something like this:
6n1a3pax
I've tried various formulae including ones like this which generate the ASCII characters for individual random numbers between an upper and lower number:
=CHAR(RANDBETWEEN(65,90)) & CHAR(RANDBETWEEN(65,90)) & CHAR(RANDBETWEEN(65,90)) &CHAR(RANDBETWEEN(65,90))& CHAR(RANDBETWEEN(65,90)) & CHAR(RANDBETWEEN(65,90)) & CHAR(RANDBETWEEN(65,90)) & CHAR(RANDBETWEEN(65,90))
However, they're lengthy, you have to repeat the RANDBETWEEN() function multiple times inside a formula, and you can't choose both "alpha" and "numeric" in the same RANDBETWEEN().
Is there any easy way to do this in Excel, Google Sheets or LibreOffice Calc? If a solution works in one and not in the others then great if you can mention which one(s).
(N.B. This is not a duplicate of questions about how to stop recalculation of randomisation functions in Excel)

Answer 1

in GS try:
=LAMBDA(x, x)(DEC2HEX(RANDBETWEEN(0, HEX2DEC("FFFFFFFF")), 8))
if that's not enough and you need
A-Z char 65-90
a-z char 97-122
0-9 char 48-58
=JOIN(, BYROW(SEQUENCE(8), LAMBDA(x, IF(COINFLIP(), IF(COINFLIP(),
CHAR(RANDBETWEEN(65, 90)), CHAR(RANDBETWEEN(97, 122))), RANDBETWEEN(0, 9)))))
frozen:
=LAMBDA(x, x)(JOIN(, BYROW(SEQUENCE(8), LAMBDA(x, IF(COINFLIP(), IF(COINFLIP(),
CHAR(RANDBETWEEN(65, 90)), CHAR(RANDBETWEEN(97, 122))), RANDBETWEEN(0, 9))))))
alternative (with better distribution):
=JOIN(, BYROW(SEQUENCE(8), LAMBDA(x, SINGLE(SORT(CHAR({
SEQUENCE(10, 1, 48);
SEQUENCE(26, 1, 65);
SEQUENCE(26, 1, 97)}),
RANDARRAY(62, 1), )))))
or frozen:
=LAMBDA(x, x)(JOIN(, BYROW(SEQUENCE(8), LAMBDA(x, SINGLE(SORT(CHAR({
SEQUENCE(10, 1, 48);
SEQUENCE(26, 1, 65);
SEQUENCE(26, 1, 97)}),
RANDARRAY(62, 1), ))))))
for more see: stackoverflow.com/questions/66201364

Answer 2

LibreOffice Calc 7.x:
A non-volatile option for LibreOffice Calc 7.x is the use of the RANDBETWEEN.NV() function:
Formula in A1:
=CONCAT(IF({1,2,3,4,5,6,7,8},MID("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",RANDBETWEEN.NV(1,62),1),))
Note that using ROW(1:8) would still force recalculation when any value in rows 1-8 have been made (thus volatile):
=CONCAT(IF(ROW(1:8),MID("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",RANDBETWEEN.NV(1,62),1),))
Excel ms365:
Unfortunately there is, AFAIK, not a non-volatile Excel equivalent to this function. If volatility is not a problem, then try:
=CONCAT(MID("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",RANDARRAY(8,,1,62,1),1))

Answer 3

Here's my take, for Google Sheets:
=lambda(_,
_
)(
lambda(
numWords, wordLength, charRegex, ascii,
lambda(
alphabet,
map(
sequence(numWords),
lambda(_,
concatenate(
map(
sequence(wordLength),
lambda(_,
mid(alphabet, randbetween(1, len(alphabet)), 1)
)
)
)
)
)
)(concatenate(filter(ascii, regexmatch(ascii, charRegex))))
)(10, 8, "[0-9a-zA-Z]", arrayformula(char(sequence(127))))
)
The formula will generate 10 passwords of 8 characters each from an alphabet that includes lower and upper case letters, and digits.
To choose which characters to include in the alphabet, replace [0-9a-zA-Z] with another regex like [0-9a-z!#$%&/] or [-!#$%&/\w]. Note that you may need to \escape any regex special characters there.
The pattern avoids the non-uniform distribution issues that plague some of the solutions presented in this thread. The ones that use coinflip() or isodd(rand()*N) will give results that overrepresent smaller sub alphabets like 0-9. The ones that use sort() will not repeat any chars in the result, which is not optimal.

Answer 4

It's possible to do this in Excel using a combination of the following functions:
SEQUENCE() VSTACK() RANDARRAY() CHAR() INDEX() TEXTJOIN()
Unfortunately this doesn't work in LibreOffice (at the moment) as it does not have the SEQUENCE() function. It does not work in Google Sheets as the RANDARRAY() function only takes 2 parameters and the VSTACK() function does not exist, although you can use braces and a semicolon, e.g. {SEQUENCE(26,1,97,1);SEQUENCE(10,1,48,1)}.
Here's the formula you need:
Upper-case e.g "413BK5S0": =TEXTJOIN("",1,INDEX(CHAR(VSTACK(SEQUENCE(26,1,65,1),SEQUENCE(10,1,48,1))),RANDARRAY(8,1,1,36,TRUE)))
Lower-case e.g. "b8etbno8": =TEXTJOIN("",1,INDEX(CHAR(VSTACK(SEQUENCE(26,1,97,1),SEQUENCE(10,1,48,1))),RANDARRAY(8,1,1,36,TRUE)))
The following explanation for each function:
SEQUENCE() - a sequence of e.g. 26 numbers, in 1 column, starting at number 65, increasing by 1 each time (with the second incidence of the function being 10 numbers starting at 48)
VSTACK() - combine the 2 SEQUENCE() formulae into 1 array (sequence) of numbers
CHAR() - the ASCII character associated with a decimal ASCII number (where the decimal number is generated by the SEQUENCE() function) - see https://www.asciitable.com/
RANDARRAY() - an array of 8 random numbers, 1 column wide, minimum number 1, maximum 36
INDEX() - the value from each element within the sequence of characters, where each of 8 element numbers is provided by RANDARRAY()
TEXTJOIN() - join the values in an array together into one cell, with no separator and ignoring empty values

Answer 5

What do you think of something like this?
=CONCATENATE(BYROW(SEQUENCE(8),LAMBDA(e,IF(ISODD(ROUNDUP(RAND()*10)),CHAR(RANDBETWEEN(65,90)),ROUNDDOWN(RAND()*10)))))
If you want to include lower case, you can do a similar logic:
=CONCATENATE(BYROW(SEQUENCE(8),LAMBDA(e,IF(ISODD(ROUNDUP(RAND()*10)),IF(ISODD(ROUNDUP(RAND()*10)),CHAR(RANDBETWEEN(65,90)),CHAR(RANDBETWEEN(97,122))),ROUNDDOWN(RAND()*10)))))
The logic is the next one: what I'm doing is with ISODD(ROUNDUP(RAND()*10) generating a random number between 1 and 10 and checking if it's odd. If it is, it generates a letter or else it generates a number. With CONCATENATE(BYROW(SEQUENCE(8)... I'm doing this 8 times and concatenating them. What I just added was a second "random and odd" time when it's time to generate a letter so you can have upper and lower case