How to recover the original disk size without losing data

If your hard drive shows less space than the capacity printed on the box, you may want to get back its original size. In most cases there is no need for drastic measures, but you should always have an up-to-date backup before changing anything.

Cloning or changing the partitions of a failing drive can make the case worse. If the files matter, first see how hard drive recovery works.

Some of the methods used to reclaim disk space, such as formatting or initializing the drive, erase the files stored on it, so back up all your data first whenever you can.

In this article, you will learn why your hard drive does not show its full capacity and how to recover the original size of your hard drive. Ready?

01Why doesn’t my hard drive show its real size?

Do you really need to recover the original size of your hard drive? First, you need to understand that the capacity Windows shows is almost never the number printed by the manufacturer – and that is not a fault, as you will see below.

It is not a system error or a defect in the drive: the difference comes from the way capacity is counted.

Why does this happen? Manufacturers state capacity in decimal units, where 1 GB is 1,000,000,000 bytes. Windows, on the other hand, counts in binary units, where 1 GB is 1,073,741,824 bytes. The number of bytes on the drive is the same; only the unit of measurement changes, which is why the operating system shows a smaller figure.

To make this clearer, here are the binary units used in computing (the ones Windows uses):

• 1 bit is a 0 or a 1;
• 8 bits equal 1 B (byte);
• 1,024 bytes equal 1 KB (kilobyte);
• 1,024 KB equal 1 MB (megabyte);
• 1,024 MB equal 1 GB (gigabyte);
• 1,024 GB equal 1 TB (terabyte).

Why 1,024 and not 1,000?

This is a common question, and the answer is simple. Computers work in binary, and 1,024 is the power of two closest to 1,000, because 2¹⁰ = 1,024. That is why, in binary, 1 KB is 1,024 bytes and not 1,000.

Understanding this is key to understanding why your hard drive does not seem to show its full capacity.

Manufacturers use the decimal system (1 MB = 1,000 KB), while Windows uses the binary system (1 MB = 1,024 KB). At the kilobyte level the difference is small, but it adds up with every unit: about 2.4% per KB, 7% per GB and almost 10% per TB.

Here is what that means in practice:

• How Windows counts: 1 GB = 1,024 × 1,024 × 1,024 = 1,073,741,824 bytes;
• How the manufacturer counts: 1 GB = 1,000 × 1,000 × 1,000 = 1,000,000,000 bytes.

So each gigabyte on the label is about 70 MB smaller than a gigabyte in Windows. On larger drives the gap grows: a 1 TB hard drive appears as roughly 931 GB, and that is perfectly normal.

However, the units are not the only reason the figures don’t match. Some drives come with preinstalled software (backup tools, for example) that takes up space. You can delete those files if you don’t need them. Formatting the drive also frees up that space, but it erases everything on it, so copy your data elsewhere first.

Another common cause, especially with an external hard drive, is space that does not belong to any visible partition: hidden partitions or unallocated space.

The drive seems smaller than it should be, but part of its capacity is simply sitting in a hidden partition or in unallocated space. To use it again, that space has to be reclaimed on the disk, by extending an existing partition or creating a new one.

02How do I check the capacity of my external hard drive?

Before you try to recover the original size of your hard drive, check how much space it actually has. There are a few ways to do this:

Through This PC (My Computer)

• Click Start;
• Open This PC (My Computer in older versions of Windows);
• Right-click the drive you want to check, for example Local Disk (C:) or your external drive, and choose Properties;
• On the General tab, check the capacity, used space and free space.

Through File Explorer

• Click Start;
• Go to All Programs, then Accessories, and open Windows Explorer (File Explorer in newer versions);
• Open This PC (My Computer in older versions of Windows);
• Right-click the drive you want to check, for example Local Disk (C:) or your external drive, and choose Properties;
• Right-click the drive, choose Properties and look at the capacity chart.

Through Computer Management

• Click Start;
• Press Windows + R, type compmgmt.msc and press Enter;
• Under Storage, click Disk Management. This is where you can also see hidden partitions and unallocated space.

03How do I recover the real size of my hard drive?

Once you know how much space your hard drive really has, you may decide to recover its original size. There are several ways to do this, but before any of them you must make a backup of your data so that nothing is lost.

Here are some options for reclaiming space on your hard drive.

Updating the hard drive driver

You may need to update the driver. In theory it should already be up to date, but sometimes you have to force the update. Follow these steps:

• Open Device Manager and expand Disk drives;
• Find the device you want to update;
• Right-click it and choose Update driver;
• Choose Search automatically for drivers, and Windows will look for the latest driver software.

Formatting the hard drive

Another way to recover the original size of your hard drive is to format it. Formatting erases all the data on the partition, so only do it after copying your files to another drive. Here’s how:

• Click Start;
• Go to Control Panel, then System and Security, then Administrative Tools;
• Open Computer Management;
• Under Storage, open Disk Management;
• Right-click the partition you want to format, choose Format and double-check that you have selected the right drive before confirming.

Converting MBR to GPT

• A disk with an MBR partition table can only use up to 2 TB; on larger drives, the rest of the capacity remains unusable. Converting the disk from MBR to GPT solves this. Tools such as EaseUS Partition Master can do the conversion without deleting partitions, but any change to the partition table carries some risk, so back up first:
• Once it is installed, open EaseUS Partition Master;
• Right-click the MBR disk you want to convert;
• Choose Convert to GPT;
• Click the pending operation button in the toolbar (Execute 1 operation) and then click Apply.

Initializing the hard drive

Finally, you can initialize the hard drive. This option is only for new drives, or drives with no data, that Windows shows as “Not initialized”. Initializing creates a new partition table and makes any existing data inaccessible. If a drive that contained files suddenly appears as “Not initialized”, do not initialize it: that is a sign of a fault, and the right step is a data recovery program or a specialized lab.

• Click Start, type compmgmt.msc and press Enter to open Computer Management;
• In the left-hand pane, under Storage, click Disk Management;
• Find the drive in Disk Management (a black bar means the space is unallocated, with no partition);
• Right-click the disk name and choose Initialize Disk.

Checking for physical faults

A less common possibility is that the missing capacity is caused by a physical fault in the hard drive. In that case, stop using it and, if the data matters, take it to a specialized data recovery lab.

04Every computer and device is different

In this article we have covered several ways of recovering the original size of your hard drive, but menus and options may have different names depending on the computer, device or version of Windows.

In other words, the steps won’t match every system down to the last detail, but in general they follow the instructions above.

If you can’t find the options you need and you are not used to this kind of task, avoid experimenting, because some options change settings or delete files.

In that case, it is better to ask professionals for help to recover the original size of your hard drive. It is the safer route, and it includes backing up all your data so that nothing is lost during the process.

05Conclusion

As soon as you connect a new hard drive, you will notice that the capacity shown by the operating system differs from the one stated by the manufacturer. This is standard across the industry and comes from the difference between decimal and binary units.

Available space can also be reduced by preinstalled software, hidden partitions or unallocated space.

If you need to recover the original size of your hard drive, there are several ways to do it, as described above – always with a backup made first.

If you still can’t solve the problem, or if you need data recovery, Bot can help.

You have two options: we collect your device free of charge (islands not included), or you drop it off at one of our reception points. Our technicians then diagnose the fault, free of charge in the standard service, and send you a quote for the data recovery.

Just fill in the form on our website and choose how you want to send us the device.

There are two ways to get your device to us: free collection or drop-off at one of Bot’s reception points in Lisbon, Coimbra, Porto and Braga.

Bot has reception points in Lisbon, Coimbra, Porto and Braga; use this link to find the one closest to you. Once you have filled in the form, you can hand the device in directly at Bot.

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This is the safest way to recover the original size of your hard drive while keeping all your data intact.

Need to recover the files? Bot runs a free diagnosis in its lab: see our hard drive data recovery service.