A yottabyte (YB) is a unit of digital data equal to 1,000 zettabytes (ZB), or 10^24 bytes, as defined by the international system of units (SI). Its binary counterpart, the yobibyte (YiB), is 2^80 bytes, about 20.9% more. For about three decades it was the largest unit with an official SI prefix. Businesses do not buy storage in yottabytes; the unit is used mainly for global-scale and theoretical comparisons.
At a glance
- Decimal: 1 YB = 10^24 bytes = 1,000 ZB = one trillion TB. Binary counterpart: 1 yobibyte (YiB) = 2^80 bytes.
- The gap between the unit and its binary counterpart is about 20.9%, the largest of the common units.
- As a rough illustration, global estimates of all data stored worldwide are a small fraction of a yottabyte.
- Since 2022, two larger SI prefixes exist: ronna (10^27) and quetta (10^30).
What problem it solves
The yottabyte mostly serves as a ceiling for comparison. It lets writers, researchers and engineers describe theoretical limits, such as the maximum addressable size of a file system or storage design, and frame long-range projections about data growth. Some file systems and storage architectures state theoretical maximum capacities in units this large to show that capacity limits are not a practical concern.
For buyers, the unit is a reminder of how the scale ladder works: each step up multiplies by 1,000. Organizations buy in terabytes and petabytes; global totals are counted in zettabytes; the yottabyte is the next step beyond that.
How it works
Decimal and binary values. 1 YB = 1,000 ZB = 10^24 bytes; 1 YiB = 1,024 ZiB = 2^80 bytes. Because the binary gap grows with each step, at this scale a YiB is about a fifth larger than a YB.
Prefixes above yotta. In 2022 the 27th General Conference on Weights and Measures (CGPM), the body that maintains the SI, added the prefixes ronna (symbol R, 10^27) and quetta (symbol Q, 10^30). That makes the ronnabyte 1,000 yottabytes and the quettabyte 1,000 ronnabytes. They remain rare in everyday use.
Theoretical limits. Some storage designs, such as 128-bit file systems, describe maximum capacities far beyond a yottabyte. These figures describe what the addressing scheme allows, not what any hardware can hold.
When it matters for buyers
- Reading specifications. When a platform quotes a maximum capacity in yottabytes or larger, treat it as “no practical capacity limit” and look instead at per-volume, per-object and per-account limits.
- Reading marketing. Yottabyte projections about the future of data describe global trends, not your requirements.
- Keeping units straight. Knowing the ladder from KB to YB helps catch errors of a factor of 1,000 in quotes, plans and reports.
Our file and object storage page covers how we help buyers compare storage on the limits and prices that actually apply to them.
Questions to ask vendors
- Is the stated maximum capacity a tested, supported limit or a theoretical addressing limit?
- What are the practical limits per volume, file system, bucket and object?
- Are quoted capacities in decimal or binary units?
How it differs from a yobibyte (YiB)
A yobibyte is 2^80 bytes, about 20.9% more than a decimal yottabyte. Both are so large that the distinction mainly matters in technical documents that state exact limits. The glossary term Binary Prefixes covers the binary units in more detail.
The storage unit ladder
Each decimal step multiplies by 1,000; each binary step by 1,024.
- Kilobyte (KB): 10^3 bytes; kibibyte (KiB): 2^10 bytes.
- Megabyte (MB): 10^6 bytes; mebibyte (MiB): 2^20 bytes.
- Gigabyte (GB): 10^9 bytes; gibibyte (GiB): 2^30 bytes.
- Terabyte (TB): 10^12 bytes; tebibyte (TiB): 2^40 bytes.
- Petabyte (PB): 10^15 bytes; pebibyte (PiB): 2^50 bytes.
- Exabyte (EB): 10^18 bytes; exbibyte (EiB): 2^60 bytes.
- Zettabyte (ZB): 10^21 bytes; zebibyte (ZiB): 2^70 bytes.
- Yottabyte (YB): 10^24 bytes; yobibyte (YiB): 2^80 bytes.