You have probably experienced this at some point: you buy an external hard drive or a personalised USB flash drive, only to find when you get home that the product has less available storage than stated on the packaging. For example, it may be labelled as 16 GB, but when you plug it into your computer and check the storage, it shows that it only has around 12 GB of available capacity, without you having added a single document. This does not just happen with these storage devices; computer hard drives and smartphones are affected too. Below, we explain why this happens.
There are several reasons for this difference. To understand it, two key concepts need to be considered: marketing and the decimal system. The storage capacity shown on the packaging is expressed using the decimal system. In other words, in this system, one megabyte is one million bytes, while one terabyte is 1,000 gigabytes.
· Measuring storage correctly: from the decimal system to binary
If you have some knowledge of computing, you will know that computers, mobile phones and other devices do not measure storage in quite the same way as manufacturers advertise it. Instead, they use the binary system, as shown in the following conversion table:
- One megabyte is 1,048,576 bytes
- One gigabyte is equivalent to 1,024 megabytes
In more technical terms, the digital devices we use — including USB storage devices — work with a base-2 system that uses only the digits 0 and 1. This system of measurement produces the conversions mentioned above, where one kilobyte is 1,024 bytes, or 2 to the power of 10.
These figures may be starting to make your head spin, or perhaps you simply do not fancy getting out a calculator. So, let us make it easier to understand why USB flash drives appear to have less storage than advertised. For every gigabyte counted using the system we use when purchasing the storage device, converting it to the binary measurement results in roughly 70 megabytes less. To round off the explanation, here is what some of the most common storage capacities typically look like:
- 16 GB will actually contain around 14.9 GB
- 32 GB will actually contain around 29.8 GB
- 64 GB will actually contain around 59.52 GB
- 1 TB will actually contain around 931 GB
· Is This Practice Legitimate?
Are manufacturers doing anything illegal or immoral by advertising their products this way? No, not at all. To understand why, we need to turn to the classic concept of the small print. Somewhere on the packaging, there will probably be text in a smaller font explaining that the decimal system is being used to state the storage capacity. In short, the seller is making it clear that the storage capacity in gigabytes and terabytes is being stated using the decimal system.
The industry itself also makes efforts to be transparent about this. On the Seagate website, one of the world’s leading manufacturers of storage drives and external hard drives, the issue is explained clearly.
Another matter arises when we buy a computer, tablet or smartphone and find that it has less storage space than advertised in the product specifications. In this case, it is important to bear in mind that the operating system powering the device takes up some of the capacity that was initially advertised.
The situation is somewhat different with some mobile phone memory cards, as their storage uses NAND and eMMC technology. In these cases, the actual available storage percentage at the outset is higher, reaching up to 99%. However, as the memory is used, the integrity of its memory blocks can deteriorate, which can eventually reduce the available capacity.
Ultimately, what happens if you need a 2 GB personalised USB flash drive? Based on what we have explained here, it is better to make sure you buy a 3 or 4 GB drive. That way, you will not run into storage capacity problems.
As you can see, there is a lot of marketing behind what initially seemed like a mystery or an error. More critical readers might consider it misleading, but in reality, the packaging is simply displaying capacity using the decimal system. If you look at the details, the information is technically correct. Do you think manufacturers should provide the exact usable capacity, or is this simply a good way of marketing these products?