Terabyte (TB) - Unit Information & Conversion

Definition

A terabyte (TB) is a multiple of the byte unit for digital information storage. The prefix tera- (symbol T) is defined in the International System of Units (SI) as a multiplier of 1012 (1 trillion, or 1 followed by 12 zeros). Therefore, 1 terabyte = 1,000,000,000,000 bytes. This is equivalent to 1,000 gigabytes (GB).

History

The SI prefix 'tera-' (meaning 1012) was adopted for use in computing as storage capacities reached trillions of bytes. Historically, the term 'terabyte' was often used ambiguously to refer to either 1012 bytes (the strict SI definition) or 240 bytes (1,099,511,627,776 bytes), which is the power of 2 closest to a trillion. This ambiguity, particularly noticeable in how operating systems reported disk sizes versus how manufacturers advertised them, led the International Electrotechnical Commission (IEC) to introduce the distinct binary prefix 'tebi-' (Ti) for 240. Thus, tebibyte (TiB) specifically denotes 240 bytes, while terabyte (TB) formally refers to 1012 bytes.

Common Uses

Terabytes are widely used to measure large amounts of digital data storage capacity:

• Specifying the capacity of consumer and enterprise hard disk drives (HDDs) and solid-state drives (SSDs).
• Measuring the size of large files, databases, archives, and backups.
• Quantifying the storage space available in cloud storage plans and data centers.
• Describing the amount of data transferred over networks or used in monthly internet data caps.
• Indicating the capacity of personal computers, laptops, external drives, and network-attached storage (NAS) devices.

Unit FAQs

How many bytes are in a terabyte (TB)?

According to the standard SI definition, there are exactly 1,000,000,000,000 bytes (one trillion bytes, or 1012 bytes) in 1 terabyte (TB).

How many gigabytes (GB) are in a terabyte (TB)?

There are 1,000 gigabytes (GB) in 1 terabyte (TB). This follows the SI prefixes: 1 TB = 1012 bytes and 1 GB = 109 bytes. Therefore, 1 TB / 1 GB = 1012 / 109 = 103 = 1,000.

What is the difference between a terabyte (TB) and a tebibyte (TiB)?

• A terabyte (TB) uses the decimal SI prefix 'tera-' and equals 1012 bytes (1,000,000,000,000 bytes). It's commonly used in storage device marketing.
• A tebibyte (TiB) uses the binary IEC prefix 'tebi-' and equals 240 bytes (1,099,511,627,776 bytes). It's often used by operating systems to report storage capacity based on powers of 2. A tebibyte (TiB) is approximately 9.95% larger than a terabyte (TB) (1 TiB ≈ 1.0995 TB).

What is the difference between a terabyte (TB) and a terabit (Tb)?

• A terabyte (TB) measures data storage capacity in bytes and equals 1012 bytes.
• A terabit (Tb) measures data quantity or data transfer speed in bits and equals 1012 bits. Assuming the standard definition of 1 byte = 8 bits, 1 terabyte (TB) is equal to 8 terabits (Tb). Calculation: 1 TB = 1012 bytes = 1012 * 8 bits = 8 * 1012 bits = 8 Tb. Therefore, a terabyte represents 8 times more data storage capacity than the equivalent number of terabits.

Why is TB often used in marketing instead of TiB?

Storage manufacturers typically market drive capacities using the decimal prefix terabyte (TB) because 1012 bytes yields a larger, rounder number compared to the equivalent value expressed using the binary prefix tebibyte (TiB) (which is 240 bytes). For instance, a hard drive containing exactly 1,000,000,000,000 bytes is advertised as 1 TB. If measured in tebibytes, this same physical capacity would be approximately 0.909 TiB (since 1012 / 240 ≈ 0.909). Using TB allows manufacturers to present higher capacity figures, which is advantageous for marketing, even though operating systems might report the capacity using the smaller TiB value.