ISO 80000-13: Quantities and Units of Information Science and Technology
ISO 80000-13 organises the vocabulary of information theory, computing and telecommunications so that data quantities stay compatible with the International System of Units. Whether you manage fibre links, cloud platforms or analytics models, these definitions keep requirements sheets, procurement specs and dashboards aligned across teams and vendors.
Use this article alongside the general principles volume and the SI base unit guide to keep log-based units, prefixes and rate measurements coherent. When you need tabular summaries for every discipline, open the ISO 80000 quick-reference tables for a panoramic view.
Information content
Defines the bit, byte and logarithmic units—shannon, hartley and nat—that translate probability into storage requirements and coding limits.
Digital infrastructure
Specifies rates, capacities and service levels for networks, processors and memory components so engineering teams can benchmark architectures consistently.
Binary prefixes
Clarifies when to use kilo vs kibi and the IEC binary prefix ladder so procurement, software and analytics all reference the same quantity of data.
Telecom performance
Anchors modulation rate, traffic intensity and quality-of-service measures in SI so service providers and regulators audit the same metrics.
Core definitions
Fundamental information quantities
ISO 80000-13 bridges theoretical and practical perspectives on information. It formalises how we quantify uncertainty, message content and algorithmic complexity so that storage engineering and communications research share the same baseline language.
| Quantity | Symbol | Unit | Definition | Usage |
|---|---|---|---|---|
| Information content | I | bit (b) | Amount of information conveyed by an event with probability p, measured as log2(1/p). ISO 80000-13 defines the bit as the coherent unit and recognises the byte (1 B = 8 b) for grouped binary digits. | Use for storage sizing, coding theory and sensor payload planning. Convert between kilobytes and megabytes with the KB to MB Converter before documenting interface requirements. |
| Information entropy | H | shannon (Sh) | Expected value of information content across all outcomes: H = −∑ pi log2 pi. One shannon equals one bit of uncertainty. | Reference when estimating compression efficiency or password strength. Pair with the Password Entropy Calculator to quantify user authentication policies. |
| Natural information content | I | nat | Information unit based on the natural logarithm: 1 nat = loge(1/p). Useful when equations leverage e-based exponentials. | Select when modelling thermodynamic analogies, machine learning loss functions or Poisson processes where e appears naturally. |
| Hartley information | I | hartley (Hart) | Logarithmic unit with base 10, defined as log10(1/p). One hartley corresponds to a decade of possibilities. | Employ in signal analysis or older telecommunications literature. Convert to bits using 1 Hart = log2(10) ≈ 3.3219 bits for interoperability. |
| Algorithmic complexity | K | bit (b) | Length of the shortest binary program that reproduces a dataset. ISO 80000-13 cites it to align information theory with computer science usage. | Frame discussions about compressibility, data governance and AI training corpus documentation. |
Prefix discipline
IEC binary prefixes for digital systems
ISO 80000-13 adopts the binary prefix system promoted by IEC 60027-2 to prevent ambiguity between decimal multiples (kB, MB) and binary multiples (KiB, MiB). Referencing the correct prefix keeps procurement invoices, firmware limits and analytics dashboards mutually intelligible.
| Prefix | Symbol | Factor | Decimal equivalent |
|---|---|---|---|
| kibi | Ki | 210 = 1 024 | ≈ 1.024 × 103 |
| mebi | Mi | 220 = 1 048 576 | ≈ 1.049 × 106 |
| gibi | Gi | 230 = 1 073 741 824 | ≈ 1.074 × 109 |
| tebi | Ti | 240 | ≈ 1.100 × 1012 |
| pebi | Pi | 250 | ≈ 1.126 × 1015 |
| exbi | Ei | 260 | ≈ 1.153 × 1018 |
| zebi | Zi | 270 | ≈ 1.181 × 1021 |
| yobi | Yi | 280 | ≈ 1.209 × 1024 |
When documenting systems, state whether capacities use decimal prefixes from the general ISO 80000 guidance or these IEC binary prefixes. The Compression Savings Estimator helps quantify differences when reporting deduplication or encoding results.
Dynamic performance
Rates, timing and transport metrics
Beyond bits and bytes, ISO 80000-13 documents the rates and timing parameters that determine how fast information flows. These quantities tie directly to the space and time and light and radiation volumes when you evaluate propagation or optical systems.
| Quantity | Symbol | Unit | Definition | Usage |
|---|---|---|---|---|
| Data rate | R | bit per second (bit/s) | Amount of binary information transmitted per second across a channel. ISO 80000-13 recognises byte/s as a derived convenience but preserves bit/s as coherent with SI. | Essential for network design, streaming services and storage replication. Use alongside the Live Streaming Bandwidth Calculator when planning broadcast workloads. |
| Symbol rate | rm | baud (Bd) | Number of modulation symbols transmitted per second. Each symbol can encode multiple bits depending on the modulation scheme. | Correlate with spectral efficiency and latency budgets. Combine with ISO 80000-7 radiometric conventions when analysing optical links. |
| Clock frequency | fcl | hertz (Hz) | Oscillation rate that drives synchronous circuits and serial interfaces. | Syncs digital logic, memory buses and communication protocols. Relate to the Data Transfer Time Calculator to translate clock speeds into throughput. |
| Latency | τ | second (s) | Elapsed time between initiating a data transfer and receiving the first bit. ISO 80000-13 treats it as a time quantity referencing ISO 80000-3. | Use with the Bandwidth-Delay Product Calculator to size transport buffers and TCP windows. |
| Throughput | T | bit per second (bit/s) | Volume of useful payload delivered per unit time after protocol overhead and retransmissions. | Benchmark data centres, content delivery networks and telemetry pipelines. Document units explicitly to avoid confusion with raw data rate. |
Quality metrics
Reliability, availability and service metrics
Service-level discussions rely on a common statistical baseline. ISO 80000-13 links communication engineering metrics to the dimensionless conventions outlined in ISO 80000-11 so ratios and probabilities remain comparable across industries.
| Quantity | Symbol | Unit | Definition | Usage |
|---|---|---|---|---|
| Bit error ratio | BER | dimensionless | Number of errored bits divided by total bits transmitted during a measurement interval. | Characterise link quality and align with quality-of-service targets. Compare with ISO 80000-11 dimensionless ratios for methodological consistency. |
| Packet loss probability | Ploss | dimensionless | Probability that a packet fails to arrive intact or within required latency bounds. | Important for streaming and control systems. Complement with the Server Uptime Percentage Calculator when translating reliability into service-level agreements. |
| Traffic intensity | A | erlang (E) | Average number of concurrent connections or calls supported by a system, equal to arrival rate times average holding time. | Plan voice and data switch capacity. Compare with queueing models to right-size infrastructure without overprovisioning. |
| Service availability | Av | dimensionless | Fraction of scheduled time that a service meets required performance criteria. | Translates uptime commitments into measurable targets. Use with ISO 80000-1 time units and reliability calculators when drafting maintenance contracts. |
Implementation guide
Putting ISO 80000-13 to work
Treat ISO 80000-13 as both a glossary and a specification playbook. Aligning units across the data lifecycle reduces integration friction and prevents silent performance regressions when teams assume different definitions.
Establish a common vocabulary
Audit documentation templates, monitoring dashboards and code repositories to ensure they use ISO 80000-13 symbols. Cross-link with the ISO 80000 overview and SI base unit primer for organisation-wide glossaries.
Align data lifecycle metrics
Map storage roadmaps, backup policies and telemetry pipelines to coherent units. Validate file sizing and replication jobs with calculators like the Compression Savings Estimator and Data Transfer Cost Calculator.
Instrument and verify
Configure observability tools to report bit/s, baud and erlang metrics with correct prefixes. Use the Ping Distance Estimator to relate latency to physical paths and the CPU Utilization Calculator when correlating compute load with throughput.
Keep exploring
Related references and tools
Continue cross-referencing ISO 80000-13 with neighbouring volumes and practical calculators to embed consistent units from design through operations.