External HDD Won't Format to Full Size, How to Resolve?

I accidentally formatted my Seagate 3TB external hard drive using power ISO to make a bootable USB. When trying to format it using the standard NTFS again, it can only be formatted to a maximum of 2TB, leaving some space unallocated. How can I obtain the entire 3TB?

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Roxanne· Answered on Aug 30, 2023

Why your external hard drives won't format to full size? The reason is typically because the partition table on your hard drive was initialized incorrectly. As we all know, a disk volume greater than 2TB cannot be supported by an MBR. As a result, owners of 3TB and 4TB hard drives will probably see less hard drive space than there should be.

Two reliable solutions can fix this problem, including converting MBR to GPT and format MBR drive of more than 2 TB with third-party software. EaseUS Partition Master can cover you in the above two methods and ensure the success and smooth of them. Here are the complete tutorials:

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Method 1. Format MBR Drive to Full Size via EaseUS Partition Master

If you want to keep the MBR partition table, you can use a professional partition tool to break the limitations of 2 TB as below:

Step 1. Launch EaseUS Partition Master, right-click the MBR partition on your external HDD, and choose the "Format" function.

Step 2. Assign a new partition label, file system, and cluster size according to your need, then click "OK." (If there is a losing data warning, click "Yes" to continue.)

Step 3. Click "Execute 1 Task(s)" from the left corner to preview the changes, then click "Apply" to begin formatting.

Method 2. Convert MBR to GPT

If the disk data is your first priority, you can use EaseUS Partition Master to convert MBR to GPT effortlessly.

Step 1. Open the "Disk Converter" window, select "Convert MBR to GPT" and "Next" to move on.

Step 2. Select the target MBR disk and click "Convert" to apply the conversion.

Then, you can format your external drive referring to method 1. Here is a related post that you may like to check:

Learn More: Fixed: SSD Not Showing Full Capacity

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