Computer memory and storage are measured in bits and bytes, with larger amounts described using either decimal units such as GB or binary units such as GiB. The difference matters: a gigabyte is 1,000,000,000 bytes, while a gibibyte is 1,073,741,824 bytes.
Bits and bytes
A bit, symbol b, is a binary digit. A byte, symbol B, is eight bits: 1 B = 8 bit. The uppercase and lowercase letters are not interchangeable, so MB means megabytes while Mb means megabits. NIST’s binary-prefix reference defines the byte as 8 bits.
Decimal and binary units of storage
Decimal prefixes use powers of 10; binary prefixes use powers of 2. For example, kB is 1,000 bytes, whereas KiB is 1,024 bytes. NIST’s guidance specifies the decimal prefixes, while its binary-prefix references define the binary values. NIST SI prefixes and NIST binary prefixes provide the underlying definitions.
| Decimal unit | Bytes | Binary unit | Bytes |
|---|---|---|---|
| kB (kilobyte) | 1,000 | KiB (kibibyte) | 1,024 |
| MB (megabyte) | 1,000,000 | MiB (mebibyte) | 1,048,576 |
| GB (gigabyte) | 1,000,000,000 | GiB (gibibyte) | 1,073,741,824 |
| TB (terabyte) | 1,000,000,000,000 | TiB (tebibyte) | 1,099,511,627,776 |
| PB (petabyte) | 1,000,000,000,000,000 | PiB (pebibyte) | 1,125,899,906,842,624 |
| EB (exabyte) | 1,000,000,000,000,000,000 | EiB (exbibyte) | 1,152,921,504,606,846,976 |
The prefixes scale by powers: k and Ki correspond to 103 and 210; M and Mi to 106 and 220; G and Gi to 109 and 230; T and Ti to 1012 and 240; P and Pi to 1015 and 250; and E and Ei to 1018 and 260. NIST’s glossary also lists 1 KiB as 1,024 bytes and 1 GiB as 1,073,741,824 bytes. NIST KiB definition; NIST GiB definition.
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How to read a capacity label
Check the symbol, its capitalization, and whether it contains an “i.” Then identify whether the unit is decimal or binary and compare the byte counts. For instance, 500 GB is 500,000,000,000 bytes under the decimal convention; a capacity expressed in GiB uses 1,073,741,824 bytes per GiB.
Older abbreviations have not always been used consistently. NIST notes that memory manufacturers commonly used megabyte for 220 bytes, while storage-device manufacturers usually used it for 1,000,000 bytes. This history helps explain why two labels that look similar may not represent the same number of bytes.
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- Designed to work with Windows or Mac computers, this external hard drive makes backup a snap just drag and drop. Reformatting may be required for Mac
- To get set up, connect the portable hard drive to a computer for automatic recognition no software required
- This USB drive provides plug and play simplicity with the included 18 inch USB 3.0 cable
- The available storage capacity may vary.
Why a drive may show less capacity than its label
A drive labeled in decimal GB or TB can appear to have a smaller number when a display reports capacity in binary-sized units. For example, dividing 1,000,000,000 bytes by 1,073,741,824 bytes per GiB gives about 0.93 GiB. That is a unit-conversion difference, not evidence by itself that the drive is missing capacity. Other factors may also affect the amount a particular device or operating system reports; the unit convention alone does not explain every display difference.
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- 【Versatile Storage Expansion – For Gaming, Work & Everyday Use】 Running out of space on your PS5 or Xbox Series X/S? This external hard drive lets you store and play PS4 / Xbox One games directly, instantly freeing up your console’s internal storage for next‑gen titles. At the same time, it handles work file backups, media libraries, and cross‑device data transfers with ease. One drive, all your needs. *（Note: PS5 / Xbox Series X|S games cannot be run or stored directly from the external hard drive. However, by offloading your PS4 / Xbox One games, you can free up valuable space for newer titles.）*
- 【Patented Silicone Sleeve – Data Protection You Can Count On】 Worried about drops? We’ve got you covered. The patented built‑in silicone sleeve acts like a shock‑absorbing armor, cushioning your drive against bumps and falls. Whether it’s important work documents, precious family photos, or hard‑earned game saves, your data deserves this level of protection.
- 【Plug & Play, Compatible with Computers & Consoles】 No complicated setup—just plug in and go. Works seamlessly with Windows, Mac, and Linux computers, as well as PS4, PS5, Xbox One, and Xbox Series X/S. Process files at the office, back up data at home, or enjoy gaming in your downtime—one drive handles all your devices, simply and hassle‑free.
- 【USB 3.0 Ultra‑Fast Transfer – No More Waiting】 Tired of watching progress bars crawl? With USB 3.0 speeds up to 5Gbps, large files transfer in seconds. Whether you’re moving work documents, transferring hundreds of gigs of games, or backing up a year’s worth of photos, you get more done in less time.
- 【Sleek, Lightweight, and Ready to Go】 Weighing just 0.16 kg—lighter than a can of soda—this compact drive features a stylish mirror‑and‑frosted finish. Toss it in your bag and go, whether you’re heading to the office, visiting a friend for a gaming session, or giving a presentation on the road.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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