ATM PIN Numbers in Amsterdam

I've heard the 4 digit pin is more likely to be accepted in Europe. Mine is 4 digits anyhow, so it's moot to me. However, if I were in your place, I'd change my pin to 4 digits if possible. Why risk being unable to use your card?

Wells Fargo messed me up by telling me I had to have a 5 digit pin for Europe. Wrong! It was four for Italy. I can't speak for The Netherlands. Call the bank and get a knowledgeable banker to answer your question. Thankfully my husband had a 4 digit pin so we were ok. I changed my 4 digit to 5 only because I was going to Europe and the bank person I saw (in person) told me I had to.
I have been all over Europe and had no problem using my 4 digit card. I just never used it in The Netherlands.

I think this is an Urban Myth, either that or ancient history. Banks in Europe issue cards with 6-digit PIN's, and I have had no problem using my 6-digit PIN anywhere in Europe.
Unless there is something fundamentally different about US-Issued cards (e.g. old technology, like not having chip-and-PIN) 6-digit PIN's will do fine.

Is there anybody out there who can say they had a 6-digit PIN and it didn't work (excluding other reasons such as exceeding the daily limit on the machine)?

I would be inclined to believe the person that actually lives in Europe and uses his 6 digit PIN all over the continent...

^^^ Just because their ATM card was rejected doesn't mean it had anything to do with the PIN. There LOTS of reasons a transaction might not go through. I've had my 4 digit ATM card rejected plenty of times. Never know why, it just happens sometimes. I go down the block to another machine with a different bank and it works just fine.

Two major US banks seem to think that a 4 digit PIN MAY be needed for "international" ATMs but didn't identify the countries or regions.

Bank of Ameria
https://www.bankofamerica.com/deposits/manage/how-to-pay-when-traveling-abroad.go

Some international ATMs support only 4-digit PINs. Be sure your PIN
does not start with a zero, and know your PIN by the numbers, as some
ATMs outside the United States do not have letters on the keypads. To
change your PIN prior to traveling, select “More Options”, select
“Change PIN” and follow the screen prompts at a Bank of America ATM.

Wells Fargo Bank
https://www.wellsfargo.com/help/faqs/debit-card/

Most foreign ATMs require a four-digit Personal Identification Number
(PIN). If your PIN doesn't meet this requirement, you can change it
before you leave on your trip — just call
1-800-TO-WELLS(1-800-869-3557) or visit any Wells Fargo ATM or
location.

I can use my 4 digit ATM card everywhere in the EU without any problem. For worldwide use always asked my bank about certain issues, but can´t remember something serious. Most important is if your card can operate on the same network like the much used Cirrus network here. I can make use of the ATM’s of ABN/AMRO, Rabo and ING, you can find them everywhere in the Netherlands, so also in Amsterdam.

If Chris says 6 digit cards can be used as well, I believe him, likely ATM’s are compatable with other networks too. But your bank in the US must make clear if your card is compatable or not and will function without a problem. Well as far as I know 4 digit cards work anyway, but it’s your bank that has to garantee that.