Every factor on AllKindsOfConverters comes from a published international standard. This hub explains what those standards are, who maintains them and how they apply to the tools you use.
The metre, kilogram, second, ampere, kelvin, mole and candela. Every derived unit on the platform is built from these seven.
Modern imperial units are defined legally in terms of SI. The inch is exactly 25.4 mm; the pound is exactly 0.453 592 37 kg.
Kilo (10³), mega (10⁶), giga (10⁹) and friends scale base units cleanly. The kibibyte / mebibyte (2¹⁰, 2²⁰) live in IEC 80000-13.
ISO 80000 governs quantity symbols across engineering, ensuring a pascal is a pascal and a newton-metre is unambiguous.
The modern metric system. Defines the seven base units (metre, kilogram, second, ampere, kelvin, mole, candela) from which every derived unit on this site is built.
International standard governing the names, symbols and definitions of physical quantities and units used in science, technology and engineering.
Authoritative U.S. guide to SI usage, including conversion factors between U.S. customary units and SI units.
U.S. legal reference for commercial weights and measures. Underpins the pound, ounce and U.S. survey foot conversions.
Defines the modern Kelvin and Celsius scales using fixed reference points. All temperature conversions on this site follow ITS-90.
Defines the difference between decimal (kB, MB, GB) and binary (KiB, MiB, GiB) data units used by the data-storage converter.
Modern legal definition of the UK imperial yard, pound and gallon in terms of SI base units.
The Trust Center walks through how we derive each conversion factor, round results and review tools over time.
Visit the Trust Center →AllKindsOfConverters is built to be auditable. This page describes exactly how a number on this site gets from a primary standard to your screen.
Unit definitions are taken from BIPM (the SI Brochure), NIST SP 811, ISO 80000 and the relevant national metrology institutes. Where a unit has multiple historical definitions (e.g. US survey foot vs international foot), we document each.
Every conversion factor is encoded as an exact rational where possible, so 1 in = 0.0254 m is stored as that exact value rather than a rounded decimal. Factors are checked against the published reference table in the standard they come from before being added.
Unlike the fixed unit factors, currency moves. Rates are fetched from a live provider with a second provider as fallback, and refreshed hourly. If both are unreachable the converter falls back to a stored snapshot and labels the result a cached snapshot with the date it was taken, so you can see that the number is not live.
When a unit redefinition occurs (e.g. the 2019 SI redefinition) or a methodology changes, we publish a note and update the affected converters within one release cycle.
Internal calculations are performed in 64-bit floating point with rationally-defined constants. Display precision is configurable per converter (default: 6 significant figures for general use, 12 for scientific tools). We never silently round before the display step.
FX rates are pulled from a primary provider and cross-checked against a secondary reference at refresh time. Mid-market rates are shown by default; retail rates include broker spreads which vary by institution. A “rates updated” timestamp is shown on every currency tool.
Conversion math is rule-based, not AI-generated. AI tooling assists with editorial drafts and code review; every published explanation and formula is reviewed by a human editor before going live.
If you find an inaccuracy, email support@allkindsofconverters.com. We log every report and credit substantial corrections on the Editorial Standards page.
Every conversion on AllKindsOfConverters traces back to a published primary source. We list the references below so reviewers, educators and auditors can verify our work.
See our methodology for how these sources are encoded, validated and refreshed.
A high-level reference for the measurement systems supported across AllKindsOfConverters. For category-specific deep dives, see the matching converter pages and learning guides.
SI is the modern form of the metric system, maintained by the Bureau International des Poids et Mesures (BIPM). Since 2019, all seven base units are defined in terms of fixed physical constants:
Modern Imperial (UK) and US customary units are now defined in terms of SI. For example, the international yard equals exactly 0.9144 metres, the international pound equals exactly 0.45359237 kg, and the US survey foot has been phased out in favor of the international foot.
Be careful: the same name can mean different things. The US gallon (≈3.785 L) is not the Imperial gallon (≈4.546 L); a US fluid ounce differs from a UK fluid ounce; the short ton and long ton are not the same as the metric tonne.
SI prefixes scale a base unit by powers of ten — from quecto (10⁻³⁰) through quetta (10³⁰). The most common are: nano (10⁻⁹), micro (10⁻⁶), milli (10⁻³), kilo (10³), mega (10⁶), giga (10⁹), tera (10¹²), peta (10¹⁵).
Internally we follow the International Temperature Scale of 1990 (ITS-90) for high-precision use.
We follow IEC 80000-13:
Each of these categories has its own converter on the platform with full per-unit definitions, authoritative factors and worked examples. Visit the corresponding tool for the canonical reference.
AllKindsOfConverters bases its conversion factors and unit definitions on internationally recognized measurement standards. This page explains which standards we use and how we reconcile differences between them.
Where multiple standards address the same quantity, we follow this priority:
Measurement standards evolve. The 2019 SI redefinition replaced the artifact kilogram with a definition based on the Planck constant. The US survey foot was phased out in 2023 in favor of the international foot. We track these changes and update affected tools, with a public note where the change is material.
Following an international standard does not certify our calculations under that standard, nor does it guarantee fitness for a regulated use case. For regulated applications, consult the controlling authority and primary source documents.
This policy describes how AllKindsOfConverters represents numbers, applies rounding, and chooses display precision. Internal mathematics is always performed in double precision; only the displayed result is rounded.
All calculations use IEEE 754 double-precision floating point, providing roughly 15–17 significant decimal digits. Conversion factors are stored at full standard precision (e.g. 1 in = 0.0254 m exactly).
We use round-half-to-even (banker's rounding), which is the IEEE 754 default and reduces statistical bias compared with always rounding half up.
Where a unit category has a clear convention (e.g. currency uses decimal places), we follow it.
For tools used in engineering contexts (pressure, force, fuel economy) we preserve the underlying full-precision value and provide enough significant figures to support downstream calculations. For safety-critical engineering you should still apply your discipline's specific rounding and tolerance conventions.
The maximum error introduced by display rounding is less than half of the last displayed digit. Chained conversions performed inside a single tool do not accumulate display-rounding error because intermediate values stay at full precision.
Every reasonable effort is made to provide accurate conversions on AllKindsOfConverters.com. This statement explains the limits of that accuracy in plain language.
Independently verify any result that will influence a safety-of-life, regulated, scientific or financial decision. For more detail see the Measurement & Conversion Disclaimer.
If you believe a conversion is wrong, please use the Corrections Policy. Verified issues are fixed and date-stamped.