What is Product ID (PID) and Installation ID Explained in Detail

What is Product ID

Once you have installed Windows, your installation is assigned a Product ID (PID). This created in part from your product key. The PID is a number identifying your Windows installation.

The PID for Windows is needed when you obtain support from Microsoft – it is used to identify your Windows installation so that your support entitlement can be determined.

Where to find your PID?

Your product ID is provided in the Activation information in System Properties.


What is Installation ID

Windows is activated based on an evaluation of your installation ID. The Installation ID is specifically designed to guarantee anonymity and is only used by Microsoft to deter piracy. The Installation ID is comprised of two different pieces of information:

  • Product ID: This is the identifier shown above.
  • Hardware hash value: This is a number that the software licensing components use to determine if your hardware has changed.


These values are combined to produce the Installation ID, which Microsoft uses to evaluate your configuration to determine if your Windows installation is genuine.

What is Hardware hash Value

The hardware hash value is an eight byte value that is created by running ten different pieces of information from the computer’s hardware components through a one-way mathematical transformation  a hashing function. This means that the resultant hash value cannot be backwards calculated to determine the original values. Further, only a portion of the resulting hash value is used in the hardware hash in order to ensure complete anonymity.

How Hash works

A processor serial number is 96 bits in length. When hashed, the resultant one-way hash is 128 bits in length. Microsoft uses only six bits from that resultant hash in activation’s hardware hash. Due to the nature of the hashing algorithm, those six bits cannot be backwards calculated to determine anything at all about the original processor serial number.

Moreover, six bits represent 64 (2^6) different values. There were over 100 million PCs sold last year worldwide. From those 100 million PCs sold, only 64 different hardware hash values could be created as part of activation.

Microsoft developed the hardware hash in this way in order to maintain the user’s privacy.

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