The decimal system (SI) and the binary system (IEC)
Digital storage measurement operates under two distinct systems that often cause confusion. The International System of Units (SI) uses decimal-based prefixes where each step represents 1,000 units. This is the system typically used by storage manufacturers and in most consumer contexts. In contrast, the International Electrotechnical Commission (IEC) system uses binary-based prefixes where each step represents 1,024 units, reflecting how computers actually process data. This binary system is preferred in software contexts and computer science.
What is a yottabyte (YB) and a yobibyte (YiB)?
A yottabyte (YB) is the largest unit in the SI decimal system, representing:
To visualize this scale, storing 1 YB would require approximately 100 billion of today’s highest-capacity 10TB hard drives.
A yobibyte (YiB) is the binary counterpart in the IEC system:
The difference between these units becomes significant at such massive scales. The YiB is about 20.89% larger than the YB, meaning:
What is a petabyte (PB) and a pebibyte (PiB)?
A petabyte (PB) in the SI system represents:
This equals about 500 billion pages of standard printed text. In practical terms, major tech companies now manage multiple petabytes of user data.
A pebibyte (PiB) in the binary system is:
The PiB is approximately 12.59% larger than the PB:
Conversion formulas for data units
Within the same measurement system:
SI (decimal) conversions:
IEC (binary) conversions:
Cross-system conversions:
Between SI and IEC:
Data storage conversion table
Unit (SI) | Equivalent in PB | Unit (IEC) | Equivalent in PiB |
---|---|---|---|
1 YB | 1,000,000,000 | 1 YiB | 1,073,741,824 |
1 ZB | 1,000,000 | 1 ZiB | 1,073,741.824 |
1 EB | 1,000 | 1 EiB | 1,073.741824 |
1 PB | 1 | 1 PiB | 1 |
1 TB | 0.001 | 1 TiB | 0.000931323 |
Practical conversion examples
Example 1: Converting 3 YB to PB (SI system)
Using the SI conversion formula:
Calculation:
Thus, 3 yottabytes equals 3 billion petabytes.
Example 2: Converting 0.5 YiB to PiB (IEC system)
Using the binary conversion formula:
Calculation:
So 0.5 yobibytes equals 536,870,912 pebibytes.
Example 3: Converting 1 YB to PiB (cross-system)
Using the cross-system conversion:
Calculation:
Approximately 888,178 pebibytes.
Why do we need these conversions?
As global data generation explodes understanding massive storage units becomes essential for:
- Cloud infrastructure planning by tech companies
- Research institutions managing large datasets
- Archiving digital heritage for future generations
- Compliance with data regulations requiring precise storage reporting
- Accurate budgeting for storage infrastructure projects
Historical context of data measurement
The evolution of storage units reflects technological progress. “Petabyte” entered common usage around 2001 when internet traffic first exceeded 1 PB/month. “Yottabyte” was formally adopted in 1991, decades before technology could approach such scales. Interestingly, the binary prefixes (kibi-, mebi-, gibi-) were created in 1998 to resolve confusion between the two systems, though adoption remains inconsistent across industries.
Frequently asked questions
How many PB in 1 YB?
In the SI decimal system, 1 yottabyte equals exactly 1,000,000,000 petabytes. This conversion uses the formula:
Since:
Therefore:
Why do we have two different measurement systems?
The decimal system aligns with metric conventions familiar in science, while the binary system reflects how computers actually allocate memory in powers of two. This discrepancy creates about a 7.37% difference at the kilobyte level, growing to 20.89% at the yottabyte scale. The IEC created binary prefixes to eliminate confusion, though SI units remain prevalent in marketing.
Which system should I use for storage calculations?
Use SI units (YB, PB) when:
- Working with storage manufacturers’ specifications
- Comparing commercial storage solutions
- Calculating network transmission speeds
- Following scientific publications
Use IEC units (YiB, PiB) when:
- Managing file systems or operating systems
- Allocating memory in programming
- Working with storage actually reported by your computer
- Performing precise technical calculations