By Emily / Last Updated May 9, 2020

Why does SSD reports wrong size?

Thanks to the optimal reading&writing performance and low latency, SSD (solid state drive) is becoming increasingly popular, and it has been a prior choice for computer users. Some users even transfer OS to SSD for a quick boot time. However, some users find their just bought brand-new SSD drive showing wrong sizefor no reasons. So why the actual capacity does not match the described capacity? The following reasons can be accounted for the SSD not showing correct size

  • Vendor's capacity calculation is different from computer OS.

  • The Virtual Memory paging file is located on the SSD/HDD.

  • The SSD drive is larger than 2TB but initialized to be MBR.

Then, how to deal with these three problems? Read on to get the answers.

How to fix “SSD reporting wrong size” issue in Windows PC?

After figuring out possible reasons for SSD showing wrong space, it’s time to get a deeper understanding of each one and check the corresponding solutions.

Solution 1. Make a conversion between vendor and OS capacity calculating method

It is well known that computers operate in binary (or base-2), which is a numeric system that only use two digits: 0 and 1. As a result, in the operating systems, the capacity is calculated on a one-step basis every 1024, so every 1024MB is 1GB, and every 1024GB is 1TB. But the hard disk manufacturers calculate the capacity on a one-step per 1000, that is to say, every 1000MB equals 1GB and every 1000GB equals 1TB, which leads to the “reduction” of SSD capacity.

For example, we buy an SSD advertised as 120GB, but it will only show about 112GB available for usage in the computer operating system. Therefore, when you find the SSD descried capacity is not same as the actual one, you can convert the capacity according to following calculation method.

NOTE: actual capacity= byte/(1024*1024*1024 *1024)
Take 120GB as an example:
In manufacturer capacity calculating: 120GB=120,000MB=120,000,000KB=120,000,000,000 bytes
Actual capacity (in computer operating system)=120,000,000,000/(1024*1024*1024)≈111.8GB
So, the actual capacity of an SSD labeled as 120GB is just about 112GB.

Solution 2. Reset the Virtual Memory paging file

Storage/memory is quite important for computers. All programs running in the computer need to be executed in memory. So if the executed programs are too large or there are multiple programs running at the same time, the memory will run out quickly.

In order to fix this problem, Windows adopts “Virtual Memory” (also Virtual Storage) technology, which means taking out some space of hard disk to work as memory supporting programs’ running. Such space is called Virtual Memory. In the hard disk, the virtual memory exists as the PAGEFILE.SYS.

The size of the Virtual Memory in the computer is exactly how much space it takes up in the hard disk. So if you find the actual size of SSD is different from the described one, you can check and reset the size of the virtual storage in the computer taking the steps below.

Step 1. Right-click “My Computer/This PC” and choose “Properties”.

Step 2. Click “Advanced system setting” in the left panel--> “Advanced” in the next mini window--> “Settings” under “Performance”.

Virtual Memory

Step 3. In the “Performance Options” windows, locate “Advanced” and click “Change”.

Step 4. Locate the drive letter of SSD, deselect “Automatically manage paging file size for all drive”, tick “Custom size” and enter the initial size and maximum size, and then click “Set” and “OK”.

Reset Virtual Memory

Step 5. Finally, reboot your computer.

Then, you can allocate the size of Virtual Memory according to your computer's situation. Setting a certain size of virtual memory will greatly benefit the smooth operation of the system, so it is not advised to cancel virtual memory directly.

Solution 3. Convert MBR SSD to GPT

If your SSD drive is over 2TB but initialized to be MBR, there is a very strong chance that the SSD reports wrong size. That is because MBR partition style only works with disk up to 2TB in size and cannot recognize the surpassing space. The rest space will be shown as unallocated space in Disk Management and you cannot see it in Windows File Explorer.

That’s why you find the SSD shows wrong capacity. In this case, you will need to convert the SSD from MBR to GPT, which can support disk beyond 2TB. For this task, you can try the following two methods.

Method 1. Using Diskpart (data loss)

First of all, you can make use of DiskPart to convert the SSD reporting wrong capacity to GPT. But it can only convert an empty disk to GPT or MBR, so you have to delete all existing partitions, which means you will lose everything on the SSD drive. Therefore, please back up files that are important in advance.

After making a backup, then press “Win+R” simultaneously to open “Run”, type “diskpart” and hit “OK”. Then input the following command:

  • list disk

  • select disk 1 (replace “1” with the disk number of your SSD)

  • clean: delete all partitions on the chosen SSD drive.

  • convert gpt

Diskpart Convert GPT

Then, your MBR SSD is converted to GPT successfully, and the rest space over 2TB can be recognized now.

Method 2. Apply a free partition manager (Without Data Loss)

As mentioned above, the Diskpart will require you to delete all partitions first on the SSD, then you can convert it to GPT successfully. So, if you don’t want to clear the disk beforehand, you can turn to a free partition manager called AOMEI Partition Assistant Standard.

Different from DiskPart, this freeware can convert any data disk from MBR to GPT, or GPT to MBR without deleting partitions, so you don’t need to take a risk that you will lose everything important.

Warning: in order to avoid data loss caused by some uncontrollable factors such as sudden power failure, making a backup is always suggested at any time.

(1) Download the freeware, install and run it, right-click the SSD and select “Convert to GPT disk”

Convert 4TB To GPT

(2) It will pop out a window to confirm the operation. Click “OK”.

4TB OK

(3) Back to the main interface, you can confirm the operations again, if there is no problem, click “Apply” on the toolbar.

4TB Apply

If the SSD is a boot disk, you can upgrade to AOMEI Partition Assistant Professional to convert system disk between MBR and GPT without removing partitions.

Further reading: SSD reports wrong size after clone

The "SSD not showing full capacity" issue can also occur after you upgrade to a larger SSD by cloning the old hard disk. After clone, you may find the SSD has the same disk space as the old one, and the rest disk space is missing. That’s because you have cloned the partition size of the original disk to the SSD drive. Therefore, when the SSD is larger than the old one, the rest beyond capacity will shown as unallocated space and cannot be utilized for data storage.

In this situation, you can create a new partition on the unallocated space via Disk Management. Or use AOMEI Partition Assistant Standard to merge the unallocated space into another existing partition (especially the C drive).

Step 1. Launch this software. Right click the C drive and select “Merge Partition”.

Merge

Step 2. Tick the unallocated space and click “OK”.

Ok

Step 3. Hit on “Apply” to commit the pending operation.

Apply

Summary

Now, you are sure to know what to do when SSD reports wrong size under different situations. The recommended software (AOMEI Partition Assistant Professional) also has other amazing features for SSD drives such as aligning SSD partitions, securely erasing SSD drive, transferring OS to SSD drive, cloning SSD to SSD/HDD, etc.

If you are a Windows Server user, please switch to the Server partition manager, which is compatible with both Server and Windows PC.