To find the maximum RAM your Windows PC supports using Command Prompt, open CMD as administrator and run: wmic memphysical get maxcapacity. Divide the resulting number (in Kilobytes) by 1,048,576 to get the maximum capacity in Gigabytes. For example, a result of 33,554,432 KB equals 32 GB.

Steps to Check Max RAM via CMD:

  1. Open the Start menu, type cmd, and select "Run as administrator".
  2. Type wmic memphysical get maxcapacity and press Enter.
  3. Convert the output: The number provided is in KB. To convert to GB, divide by

    1,0241 comma 024

    1,024 twice (or by

    1,048,5761 comma 048 comma 576

    1,048,576).
    • Example: 16777216 KB /

      10241024

      1024 /

      10241024

      1024 = 16 GB

This video shows how to check the maximum RAM capacity of your computer:

https://www.youtube.com/watch?v=_vMn2qkO6r4
 

Alternative Commands:

  • wmic memphysical get maxcapacityEx: Sometimes provides more accurate or detailed output for modern systems.
  • wmic memphysical get memorydevices: Shows the total number of RAM slots available on your motherboard.

Notes:

  • The command reflects the maximum capability of your motherboard, not necessarily the current OS limitations.
  • Some older or specific manufacturer models may report incorrect values, so verifying with the manufacturer's specification sheet is recommended. 


To determine your motherboard's supported DDR type using the Command Prompt (CMD), you can use the wmic utility. This allows you to check the RAM currently installed, which matches your motherboard's physical slots.

Method 1: Direct Memory Type Code

This is the fastest way to get a specific numeric code representing your DDR version

  1. Open Command Prompt as an administrator.
  2. Type the following command and press Enter:
    wmic memorychip get memorytype
  3. Identify the Result: Match the number returned to these standard codes:
    • 21: DDR2
    • 24: DDR3
    • 26: DDR4
    • 0: Unknown (Often indicates DDR4 or DDR5 on newer systems where the command is outdated).

Method 2: SMBIOS Type (For Newer Systems)

If Method 1 returns "0" or "Unknown," try this command which uses updated SMBIOS definitions:

  1. In CMD, enter:
    wmic memorychip get SMBIOSMemoryType
  2. Identify the Result:
    • 26: DDR4
    • 34: DDR5

Method 3: Part Number Lookup (Most Reliable)

Since software commands can sometimes be outdated, looking up your specific RAM model is the most accurate manual check.

  1. Run this command:
    wmic memorychip get partnumber
  2. Copy the Part Number displayed (e.g., M471A1G43EB1).
  3. Search for that part number on a search engine or the manufacturer's website to see its exact DDR specifications.

Method 4: Identify Motherboard for Full Compatibility

To find what your motherboard supports beyond what is currently installed (e.g., max speed or capacity)

  1. Run this command to find your motherboard model:
    wmic baseboard get product,Manufacturer
  2. Use the Crucial Advisor tool or Newegg Memory Finder with that model name to see all supported RAM upgrades.

These guides offer methods for identifying your motherboard's supported DDR type:

https://learn.microsoft.com/en-us/answers/questions/5598658/how-can-i-find-my-laptop-memory-is-ddr4-or-ddr5

https://www.crucial.com/articles/about-memory/is-my-ram-compatible-with-my-motherboard#:~:text=There%20are%20a%20couple%20ways%20to%20determine,manufacturer%2C%20or%20run%20a%20RAM%20compatibility%20checker.

 

💡 About the Author:
Sana-Allah Kheiri, known as Sasan Ace, is the founder of Paratopic Technologies LLC and leads the company’s research and development in AI, cybersecurity, and digital freedom initiatives. Through his blog and technology campaigns, he advocates for the decentralization of digital rights in authoritarian-leaning environments. Refer to his LinkedIn for more insights.