International driving permit

Yes you need one. Whether you will be required to produce it or not is another matter but it is still required. A small amount to pay to avoid a substantially greater fine.

Are you planning to drive the rental car from Germany to the Netherlands or rent a car in Netherlands?

Driving the rental from Germany to Netherlands.

To be clear: you need an IDP and your valid driver's license (presumably from a US state or Canadian province). The IDP isn't a license of any sort, it merely serves as an offically-recognized translation of the terms on your (valid and still needed) drivers license. There's no test, you just fill out a form, show your actual license, get your photo snapped, and hand over some money (around US$28 as I recall).

IDPs are cheap, quick and easy to get. You may not "need" one if all goes well, but (just like insurance) if something goes sideways, you're really going to want to have it (or wish that you did). To me, it's a no-brainer and is on my pre-travel task checklist for any trip where I might possibly rent a car. Having one with me probably saved me from a v-e-r-y expensive traffic ticket one time when I was in Japan...

Driving the rental from Germany to Netherlands.

Not sure if you are intending to return the car in the Netherlands or back in Germany, but presumably you know that renting in one country and returning the car in a different one usually comes with a very stiff fee (and if you are planning that, be sure to check the cost of doing so, it can be a big surprise).

Official info about validity of foreign driving licences in the Federal Republic of Germany.

We spent 13 days, without an IDP, driving around Germany during this past Summer. We thought an IDP was only required if your license is written in "Non-Roman alphabet" or alphabets using symbols. The idea being your license must be readable by police. Bottom line is we were not asked by the rental company. Although, countries other than Germany may require an IDP.

I have rented a car in Germany several times within the past year. In each case, the second item of documentation requested by the rental agent, after my passport, was my IDP. Have I rented cars in the past without being asked to produce one? Yes.

This is super simple: you can choose to not take the ten minutes and spend the couple bucks it takes to pick up an IDP before you leave on your trip. When you get to the rental counter, they may not ask you to produce it. But when they ask you for your IDP and you DON’T have one, then what is your plan? When they DID ask me, and I produced it, I was out the door with my keys three minutes later. When they deny you the rental car, are you prepared to take the train or bus?

I'd be less worried about not having an IDP if challenged at the rental car counter. I'd be a lot more concerned if stopped by a cop or, worst of all, if I were in some sort of accident. Then the cost of an IDP would seem like quite the bargain in retrospect.

Is there a particular reason you're using a car from Germany to the Netherlands? With such a very short Itinerary it would be much faster to use the high speed trains which will allow more touring time in each destination you'll be visiting. It would also avoid the hefty drop charge for renting a car in Germany and dropping it off in the Netherlands. There's also the issues of parking, tolls and high fuel costs.

Thank you all for your advice. I went and obtained the IDP to avoid any issues. To be clear, I am renting and returning the car in the SAME location. My brother is working in Germany, so I plan to explore the surrounding smaller towns during his hours of work. And We chose to drive to Amsterdam so we could stop in other towns along our way. Thanks!

lmnixon23 - I wouldn't advise you driving into the Netherlands from Germany to drop off car. The fees will be very steep. Take a train from your last stop in Germany to Netherlands then rent a car there for your second leg of your trip. Many of my fellow posters also share the same idea.

MarkK provided the best reference on the subject. Its not about what the rental agency wants or asks for, its about what is legal to drive with. Every police officer in Europe is not required to read and understand English, in latin alphabet or not, nor trained to recognize all the possible versions of local drivers licenses.

lmnixon23 - I wouldn't advise you driving into the Netherlands from Germany to drop off car.

The OP has confirmed that the car is being rented and returned at the same location in Germany.

This is probably a stupid question, but where do you get an IDP? Post office?

In the USA, at AAA (the "Auto Club" aka "triple A" or American Automobile Association). Quick, cheap, easy.

Good old American Automobile Association, AAA.

And, you don't have to be a AAA member. Here are all the details:

https://www.aaa.com/vacation/idpf.html

Some car rental agencies will not rent without it.