Understanding file sizes | Bytes, KB, MB, GB, TB, PB, EB, ZB, YB

In the digital world, data is stored, processed, and transferred using a binary system based on bits and bytes. Understanding memory and storage units is important for learning how computers manage information and perform tasks efficiently. Different units are used to measure data size and storage capacity in digital devices.

• Bit and Byte: A bit is the smallest unit of data represented as 0 or 1, while 8 bits together form a byte.
• Storage Units: Kilobyte (KB), Megabyte (MB), Gigabyte (GB), and Terabyte (TB) are used to measure digital storage and file sizes.
• Importance: These memory units help computers organize, process, and store information efficiently.

Computer Memory and Storage Units

• A computer processor is made up of many electronic circuits that can be either OFF or ON. These two states are represented in binary form as 0 and 1, which are called bits or Binary Digits.
• A group of eight bits is known as a Byte. One byte can represent values from 00000000 to 11111111, giving a total of 256 possible combinations.
• Computers use bytes to store and represent all types of information, including characters, numbers, and symbols. Multiple bytes can also be combined together to represent larger values and complex data.
• Memory is commonly measured in units such as Kilobytes (KB) and Megabytes (MB). A Kilobyte equals 1024 bytes, and a Megabyte equals 1,048,576 bytes, because computers follow the binary number system.
• Both RAM (main memory) and disk storage are measured using these units, but they have different purposes. RAM is used for temporary data processing, while disk storage is used for permanently saving files, applications, and other information.

Basic Units of Data Storage

Bit: The Smallest Unit of Data

A bit is the smallest unit of memory in a computer. It can either be 0 or 1, representing the binary system that all computers rely on. This binary system forms the foundation of all digital data.

Nibble: A Step Up from a Bit

A nibble is made up of 4 bits, which is half of a byte. Nibbles are sometimes used in computing, though they're not as common as bytes. A nibble can also be represented as a single hexadecimal digit.

Byte: The Basic Unit for Data Storage

A byte is a unit of data that consists of eight bits, and it is used to represent characters like letters, numbers, or symbols in a computer. One byte can store one character, such as "A" or "7." Storage in computers is typically measured in multiples of bytes, with common units like kilobytes (KB), megabytes (MB), and gigabytes (GB).

Historically, the term kilobyte (KB) was used to represent 1,024 bytes, but for simplicity, many people began referring to it as 1,000 bytes. This led to confusion, especially as file sizes grew larger. To address this, organizations like the IEC and NIST introduced new terms like kibibyte (KiB) for 1,024 bytes and mebibyte (MiB) for 1,048,576 bytes. However, the old terms like kilobyte and megabyte, still commonly used to mean 1,000 bytes and 1,000,000 bytes, have remained popular despite these changes.

Unfortunately, it seems that the actions of these regulators have not helped to clarify the difference between the kilobyte and the kibibyte. The fact that word "kilobyte" has simply become too deep-rooted in international culture.

Larger Units of Data Storage

As data sizes increase, we move into larger units that can handle more information.

Kilobyte

The kilobyte is the smallest unit of memory measurement but greater than a byte. A kilobyte is 10³ or 1,000 bytes abbreviated as ‘K’ or ‘KB’. It antecedes the Mega Byte, which contains 1,000,000 bytes. One kilobyte is technically 1,000 bytes, therefore, kilobytes are often used synonymously with kibibytes, which contain exactly 1,024 bytes (2¹⁰). 
Kilobytes are mostly used to measure the size of small files. For example, a simple text document may contain 10 KB of data and therefore it would have a file size of 10 kilobytes. Graphics of small websites are often between 5 KB and 100 KB in size. Individual files typically take up a minimum of four kilobytes of disk space. 

1 KB = 1,024 Bytes

Megabyte

One megabyte is equal to 1,000 KBs and antecedes the gigabyte (GB) unit of memory measurement. A megabyte is 10⁶ or 1,000,000 bytes and is abbreviated as "MB". 1 MB is technically 1,000, 000 bytes, therefore, megabytes are often used synonymously with mebibytes, which contain exactly 1, 048, 576 bytes (2²⁰). 
Megabytes are mostly used to measure the size of large files. For example, a high-resolution JPEG image might range in size from 1-5 megabytes. A 3-minute song saved in a compressed version may be roughly 3MB in size, and the uncompressed version may take up to 30 MB of disk space. Compact Disk’s capacity is measured in megabytes (approx 700 to 800 MB), whereas the capacity of most other forms of media drives, such as hard drives and flash drives, is generally measured in gigabytes or terabytes. 

1 MB = 1024KB = 1,048,576 Bytes

Gigabyte

One gigabyte is equal to 1,000 MBs and precedes the terabyte(TB) unit of memory measurement. A gigabyte is 10⁹ or 1,000,000,000 bytes and is abbreviated as "GB”. 1 GB is technically 1,000,000,000 bytes, therefore, gigabytes are used synonymously with gibibytes, which contain exactly 1,073,741,824 bytes (2³⁰). 
Gigabytes, are sometimes also abbreviated as "gigs, " and are often used to measure a storage device's capacity. e.g., a standard DVD drive can hold 4.7 GB of data. Storage devices that hold 1, 000 GB of data or more are measured in terabytes. 

1 GB = 1024MB = 1,048,576 KB = 1,073,741,824 Bytes

Terabyte

One terabyte is equal to 1,000 GBs and precedes the petabyte(PB) unit of memory measurement. A terabyte is 10¹² or 1,000,000,000,000 bytes and is abbreviated as "TB". 1 TB is technically 1 trillion bytes, therefore, terabytes and tebibytes are used synonymously, which contains exactly 1, 099, 511, 627, 776 bytes (1, 024 GB) (2⁴⁰). 
Mostly the storage capacity of large storage devices is measured in TeraBytes. Around 2007, consumer hard drives reached a capacity of 1 TeraByte. Now, HDDs are measured in Terabytes e.g., a typical internal HDD may hold 2 Terabytes of data whereas some servers and high-end workstations that contain multiple hard drives may even have a total storage capacity of over 10 Terabytes. 

1 TB = 1024 GB = 1,048,576 
MB = 8,388,608 KB = 1,099,511,627,776 Bytes

Petabyte

One petabyte is equal to 1,000 TBs and precedes the exabyte unit of memory measurement. A petabyte is 10¹⁵ or 1,000,000,000,000,000 bytes and is abbreviated as "PB". A petabyte is smaller in size than a pebibyte, which contains exactly 1, 125 899 906, 842, and 624 (2⁵⁰) bytes. 
Most storage devices can hold a maximum of a few TBs, therefore, petabytes are rarely used to measure the memory capacity of a single device. Instead, PetaBytes are used to measure the total data stored in large networks or server farms. For example, Internet Giants like Google and Facebook store more than over 100 PBs of data on their data servers. 

1 PB = 1024 TB = 1,048,576 GB = 1,073,741,824 
MB = 1,099,511,627,776 KB = 1,125,899,906,842,624 Bytes

Exabyte

One exabyte is equal to 1, 000 PBs and precedes the zettabyte unit of memory measurement. An exabyte is 10¹⁸ or 1,000,000,000,000,000,000 bytes and is abbreviated as "EB". Exabytes are lesser than exbibytes, which contain exactly 1,152,921,504,606,846, and 976 (2⁶⁰) bytes. 
The exabyte unit of memory measurement is so large, that it is not used to measure the capacity of storage devices. Even the data storage capacity of the biggest cloud storage centers is measured in PetaBytes, which is a fraction of 1 EB. Instead, exabytes measure the amount of data over multiple data storage networks or the amount of data that is being transferred over the Internet for a certain amount of time. E.g., several hundred exabytes of data are transferred over the Internet every year. 

1 EB = 1024 PB = 1,048,576 TB = 1,073,741,824 
GB = 1,099,511,627,776 MB = 1,125,899,906,842,624 KB = 
1,152,921,504,606,846,976 Bytes

ZettaByte

One zettabyte is equal to 1, 000 exabytes or 10²¹ or 1,000,000,000,000,000,000,000 bytes. A zettabyte is a little bit smaller than a zebibyte contains 1,180,591,620, 717,411,303,424 (2⁷⁰) bytes, and is abbreviated as "ZB". One zettabyte contains one billion TBs or one sextillion bytes which means it will take one billion one-terabyte hard drives to store one zettabyte of data. Generally, Zettabyte is used to measure large amounts of data and all the data in the world is just a few zettabytes. 

1 ZB = 1024 EB = 1,048,576 PB = 1,073,741,824
TB = 1,099,511,627,776 GB = 1,125,899,906,842,624 MB = 
1,152,921,504,606,846,976 KB = 1,180,591,620,717,411,303,424 Bytes

Yottabyte

A yottabyte is the largest SI unit of data measurement. It is equal to 1,000 zettabytes and contains 1,000,000,000,000,000,000,000,000 bytes, which is abbreviated as "YB." In decimal terms, 1 yottabyte (YB) contains 1,000,000,000,000,000,000,000,000 bytes or 10^24 bytes.

In binary terms, however, the yottabyte is slightly larger, corresponding to 1,024 zettabytes and 1,208,925,819,614,629,174,706,176 bytes. This is called a yobibyte (YiB) and contains exactly 2^80 bytes.

While the yottabyte is a massive measurement, it’s rarely used in practical contexts since the total amount of data in the world is far smaller than this. However, for completeness: 

1 YB = 1,000 ZB
1 YB = 1,048,576 EB
1 YB = 1,073,741,824 PB
1 YB = 1,099,511,627,776 TBz 1 YB = 1,125,899,906,842,624 GB
1 YB = 1,152,921,504,606,846,976 MB
1 YB = 1,180,591,620,717,411,303,424 KB
1 YB = 1,208,925,819,614,629,174,706,176 Bytes

So, 1 yottabyte (decimal) contains 10^24 bytes, while 1 yobibyte (binary) contains 2^80 bytes.

Bronto Byte, Geop Byte, and Sagan Byte are not real units of data storage that we use today. They are theoretical or hypothentical terms to imagine how much data we could store in the future, way beyond what we can handle now.

Right now, the biggest unit we use is a yottabyte, which is still much smaller than these made-up terms. So, these large units like Bronto Byte or Sagan Byte don’t really exist or get used for storing data at the moment.

Some Important Notes:

• The size of a disk with one KB is typically 1024 Bytes although 1,000 Bytes of data might be mentioned
• The download speed Kbps is typically 1,000 Bits per second, not 1,024 Bits per second.
• In general it is a good idea to consider 1KB as around 1000 bytes and 1MB as around 1000 KBs. Please note there is only a difference of just 5% between 1024 and 1000

Tabular Representation of Various Memory Sizes 

Data Transfer Speeds

When transferring data between devices, speed is an important consideration. Data transfer speed can be measured in bits per second (bps) or bytes per second (Bps). Here’s a breakdown of common data transfer rates:

• 1 bit per second (bps) is the smallest unit of data transfer speed.
• 1 byte per second (Bps) is equivalent to 8 bits per second.
• 1 kilobyte per second (KBps) = 1,024 bytes per second.
• 1 megabyte per second (MBps) = 1,024 kilobytes per second.
• 1 gigabyte per second (GBps) = 1,024 megabytes per second.

The fastest data transfer speed recorded was 1.84 petabits per second (Pbps) in October 2022, which translates to a speed of approximately 14.7 billion megabits per second (Mbps).