To check the maximum RAM capacity in Windows 10, open Command Prompt and run wmic memphysical get maxcapacity, memorydevices. Divide the MaxCapacity number by 1,048,576 to get gigabytes, and MemoryDevices tells you how many slots the board has. Then confirm the figure in your motherboard or laptop manual, because the real limit is the lowest of three things: what the motherboard supports, what the processor supports, and what your edition of Windows supports.
Here’s how to find each of those numbers, how many slots you have free, and how to avoid buying RAM your PC can’t use.
Step 1: Check how much RAM you have now
- Press Ctrl + Shift + Esc to open Task Manager. Click More details if you see the small view.
- Go to the Performance tab and click Memory.
- Note the total at the top right, and look at Slots used (for example, “2 of 4”), Speed, and Form factor (DIMM for desktops, SODIMM for laptops).
You can also see installed RAM in Settings > System > About, next to Installed RAM.
Step 2: Find the maximum the motherboard reports
Using Command Prompt
- Press Windows + S, type cmd, and open Command Prompt.
- Run:
wmic memphysical get maxcapacity, memorydevices - MaxCapacity is in kilobytes. Divide it by 1,048,576 to convert to GB. For example, 67108864 means 64 GB.
- MemoryDevices is the number of memory slots.
Using PowerShell
WMIC is being phased out of Windows, so if it’s missing, open PowerShell and run:
Get-CimInstance Win32_PhysicalMemoryArray | Select-Object MaxCapacityEx, MemoryDevices
MaxCapacityEx is also in kilobytes. Use the same conversion.
Treat this number as a starting point. It comes from the BIOS and is sometimes out of date. Some boards support more RAM after a BIOS update than they report, and some report a theoretical figure higher than what’s tested.
Step 3: Confirm with the manufacturer
- Find your exact model. Press Windows + R, type
msinfo32, and look at System Manufacturer, System Model, and BaseBoard Product (the motherboard). - Search the manufacturer’s support site for that model and open the specifications or manual.
- Look for “Maximum memory,” along with the supported type (such as DDR4) and speed.
For laptops, also check whether any RAM is soldered to the board. Many thin laptops have some or all memory built in, which limits how much you can add.
Step 4: Check your processor’s limit
Every CPU supports a maximum amount of memory. Find your processor name in Task Manager > Performance > CPU, then look up its specifications on Intel’s or AMD’s website. Most modern desktop processors support 64 GB or more, but older and low-power chips can be much lower.
Step 5: Check your Windows 10 edition
| Windows 10 version | Maximum RAM |
|---|---|
| 32-bit (any edition) | 4 GB |
| Home, 64-bit | 128 GB |
| Pro and Education, 64-bit | 2 TB |
| Pro for Workstations and Enterprise, 64-bit | 6 TB |
To check yours, go to Settings > System > About and look at Edition and System type. If you’re on 32-bit Windows, anything above 4 GB is wasted until you move to 64-bit.
How to work out what to buy
- Your real maximum is the lowest of the motherboard, CPU, and Windows limits.
- Per-slot capacity is roughly the maximum divided by the number of slots. A board with a 64 GB maximum and four slots takes up to 16 GB per stick.
- Use matched pairs in dual-channel boards for best performance, and fill slots in the order the manual recommends.
- Match the type (DDR3, DDR4, DDR5) and form factor. They aren’t interchangeable.
- Speed can be faster than the board supports, but it’ll run at the supported speed.
Desktop vs. laptop upgrades
Desktops usually have two or four full-size slots that are easy to reach, so upgrading to the board’s maximum is simple. Laptops vary much more: some have two removable slots, some have one slot plus soldered memory, and many ultrabooks have no upgradeable RAM at all. Check the laptop’s service manual or the manufacturer’s support page before buying anything.
Why Windows might show less RAM than installed
- Hardware reserved memory is set aside for integrated graphics and devices.
- A stick isn’t seated properly or is faulty. Reseat it, or test with Windows Memory Diagnostic.
- The BIOS needs updating to recognize newer, larger modules.
- A boot setting limits memory. In
msconfig> Boot > Advanced options, make sure Maximum memory is unchecked.
Related: How to check memory on Windows 10.
Related: How to check RAM type in Windows 10 with CMD.
Related: check maximum RAM capacity in Windows 11.
Frequently asked questions
Is the wmic result always accurate?
Not always. It’s a good estimate, but the manufacturer’s specification is the more reliable source.
Can I add more RAM than the stated maximum?
Sometimes newer, higher-capacity modules work after a BIOS update, but it isn’t guaranteed. Stick to tested limits unless you can return the RAM.
How much RAM do I need for Windows 10?
8 GB is comfortable for everyday use, and 16 GB or more helps with gaming, photo or video editing, and many browser tabs.
How do I see how many RAM slots are free?
Task Manager’s Memory page shows Slots used, such as “2 of 4.”
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.