As you know, the actual available space of storage devices usually is less than advertised. Hence, you need to calculate the real capacity based on the advertised capacity. The operation is complicated and time-consuming. To improve your work efficiency, you can use hard drive space calculators recommended by Partition Magic in this post.

It is a common phenomenon that USB/SSD/hard drive has less space than it should be. How to quickly calculate the actual available space after learning the advised storage space? Hard drive space calculators come into use. They can quickly calculate the real capacity based on claimed space.

This post collects several free online hard drive space calculators. You don’t have to install any program on your computer. Instead, you just need to navigate to the official website of the selected hard drive capacity calculator, type the advertised disk size of your storage device, choose the disk space unit (optional), and click the CALCULATE button (optional) to get the result.

You are only required to ensure that your network is stable and fast before starting the calculation.

Further reading:

MiniTool Partition Wizard is a multifunctional partition manager for Windows PCs. With this software, you can create/format/extend/shrink/merge/split/copy/delete/recover partitions, check disk space usage, perform hard drive speed tests, increase disk space, clean up computers, etc. It can be used as a USB speed tester, SSD optimizer, NTFS undelete software, bootable data recovery software, and so on.

MiniTool Partition Wizard FreeClick to Download100%Clean & Safe


The hard drive capacity calculator from is easy to use. You just need to type the claimed capacity in the left window and choose the unit for the result. Then the hard drive capacity calculator will show you the results in the right window in a few seconds.

The available units for claimed capacity and real capacity include TB and GB.
calculate the space
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The hard drive size calculator offered by can also help you calculate the actual capacity quickly. However, it doesn’t allow you to type the advertised hard drive size based on your specific situation. It only shows you the actual capacity for the listed advertised hard drive sizes as shown in the picture below.

Besides, the storage space unit is fixed, so you can’t customize it according to your needs. In a word, this hard drive capacity calculator lacks flexibility.

find the actual capacity
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The hard drive size calculator from is also capable of calculating the real capacity out of claimed capacity. Follow the steps below if you want to calculate the actual space via this hard drive space calculator.

Step 1: Go to this page.

Step 2: Manually type the advertised disk size in the corresponding field. Alternatively, you can click the up or down icon to input your disk size.

The unit for the disk size is set to TB which can’t be changed. You need to pay attention to that when you enter the number.

Step 3: Click on the CALCULATE button to get the result. After a while, the result will be shown in the Actual Available Capacity field.

figure out the actual available capacity

This website also lists the actual available space of advertised storage space ranging from 1 to 22TB. If you have that needs, you can refer to the table.

Are you looking for a hard drive space calculator? If so, you come to the right place. In this post, top 3 hard drive capacity calculators are collected. You can pick one from them to calculate the actual available disk space of your storage device.

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