Credits and licences

Last updated 2026-10-11

Our own code

The tools and page layouts are written for this site. The pages make no requests to other servers.

The calculators use published standards, public-domain data and textbook formulas, typed into our own code (no third-party libraries are used):

Thermocouple reference functions: NIST ITS-90 Thermocouple Database (NIST Monograph 175), public domain; coefficients transcribed from the public-domain thermocouples_reference package’s NIST module.
RTD equation and tolerance classes: IEC 60751 (Callendar–Van Dusen constants).
IP codes: the IEC 60529 coding system; NEMA enclosure types: NEMA 250 type definitions; NEMA → IP minimums: manufacturer cross-references (a NEMA type meets or exceeds an IP rating, it is not equivalent).
4–20 mA fault limits: NAMUR NE 43 signal ranges.
Resistor colour code and preferred values: IEC 60062 and IEC 60063 (E-series).
PCB trace width: the IPC-2221 curve fit (k = 0.048 / 0.024).
Physical constants: exact SI values (speed of light, Planck constant, elementary charge) and μ0 (CODATA).
Inductance: Wheeler’s formulas; 555 timer: the standard data-sheet formulas; crossovers, filters, op amps, motors and actuators: textbook formulas written out in each calculator’s steps.

None at present. If we add any library, font or data set, it will be listed here with its licence and a link (data/credits.json, rendered below).