Clear methods.
Useful answers.

ToConvert converts a value through a reference unit for its physical quantity. Most conversions use a scale factor. Temperature scales also need an offset; fuel consumption and wavelength can require reciprocal calculations.

Calculation methods

For a proportional conversion, the input is multiplied by the source unit’s reference factor and divided by the target unit’s reference factor. Absolute temperatures are converted through kelvin. Electromagnetic frequency and vacuum wavelength use λ = c / f, with c = 299,792,458 m/s.

Numeric calculations use decimal arithmetic with 40 significant digits internally. Results normally display 10 significant digits; the precision control allows 6, 10, 15 or 20. Display precision does not make an approximate or historical unit definition exact. Number-base conversion uses arbitrary-size integer arithmetic and accepts whole numbers in bases 2 through 36.

Sources and verification

The catalogue was inventoried against the public unit lists at UnitConverters.net. Its published numerical factors provide coverage for regional and specialist units. Common-unit definitions were checked and normalized using the references below. The interface, explanatory text and calculation implementation are original.

• NIST SP 811, Appendix B.8, conversion factors and unit conventions.
• BIPM SI Brochure, SI units, prefixes and defining constants.
• NIST SI prefixes, decimal-prefix notation.
• ExchangeRate-API documentation, the daily fiat reference-rate feed.
• Coinbase exchange-rate documentation, the BTC reference-rate feed.

The specialist and historical catalogue is a reference collection, not a claim of independent certification for every entry. Historical definitions may vary by region or period. Use the unit’s full label and confirm the applicable standard for a specification, contract or instrument.

Conventions that matter

• US liquid gallons and Imperial gallons are separate units. Dry measures have a separate converter.
• Decimal data units (kB, MB, GB) use powers of 1,000. Binary data units (KiB, MiB, GiB) use powers of 1,024.
• Temperature intervals omit the offsets used for absolute temperature readings.
• Calendar months and years are not fixed durations. Named time units use their reference definitions.
• Absorbed dose and equivalent dose are different physical quantities. Cross-conversion is blocked without a radiation weighting factor.
• Logarithmic sound levels require a reference before conversion to a physical amplitude or intensity.

Currency rates

The currency converter loads daily fiat rates from ExchangeRate-API and BTC reference rates from Coinbase. Fiat timestamps come from the provider; the BTC timestamp records retrieval time. Data is cached in your browser until the next daily fiat update or for five minutes for BTC. If a service fails, a recent browser cache is explicitly marked as stale; expired or missing data is not replaced with estimated rates. Fiat caches older than seven days and BTC caches older than one hour are rejected. Rates exclude spreads and fees. CUC, KPW and STD have no supported rate and remain unavailable.

Input and rounding

Use a period for decimals and optional comma grouping, such as 1,234.5. Fractions such as 1/2 and mixed numbers such as 5 1/2 are supported by quantity converters. Scientific notation such as 2.5e6 is also accepted. The calculator rejects malformed input, division by zero and absolute temperatures below 0 K.

Content and review

Conversion pages contain the working tool, the formula and a numerical table. The initial catalogue was assembled on October 14, 2026. Automated checks cover known reference values, inverse conversions, input validation and generated internal links. They do not replace a domain expert’s review of all specialist definitions.