About Our Calculations

Turbo Unit Converter is an independent tool. It is not certified, audited, or endorsed by NIST or any standards body. Calculations are based on NIST standards for the International System of Units (SI), and conversion factors are taken from publicly published reference tables — primarily NIST Special Publication 811 Appendix B and IEEE/ASTM SI 10.

Where a unit has a defined exact value (for example, 1 inch = 0.0254 m exactly), we use the exact factor. Where a factor is conventional or experimentally determined, we use the value published by NIST or BIPM at the precision shown in the conversion table.

1. Every category defines a canonical SI base unit (metre, kilogram, second, kelvin, ampere, candela, mole, plus coherent derived units such as pascal, watt, joule).
2. Each supported unit stores an exact or NIST-published factor to the base unit. The input value is first converted to the base unit, then from the base unit to the target unit.
3. Temperature (°C, °F, K, °R) uses the additive offset formulas defined by the International Temperature Scale of 1990 (ITS-90), not a single multiplicative factor.
4. Math runs in IEEE 754 double precision in the browser. Displayed values are rounded for readability; the underlying calculation keeps full precision.
5. Derived units scale with dimension: a length factor f becomes f² for area and f³ for volume, per SP 811 §4.

We follow the rounding guidance in NIST SP 811 §7.9: results are rounded only at the final step and never carry more significant figures than the least precise input. For everyday use, 2–4 decimal places is usually appropriate; for engineering, scientific, or regulatory work, copy the full-precision value shown in the result field rather than the rounded display.

• NIST Special Publication 811 — Guide for the Use of the International System of Units (SI)
• NIST Reference on Constants, Units, and Uncertainty
• NIST — Writing SI (Metric System) Units
• BIPM — The International System of Units (SI Brochure, 9th ed.)
• IEEE/ASTM SI 10 — American National Standard for Metric Practice