Every converter on Units Verse is built on a single, auditable model. This page explains exactly how a value entered on one side becomes the value shown on the other.
1. Every category has a base unit
Within a category, all units are defined relative to one base unit drawn from the International System of Units (SI) wherever one exists — the metre for length, the kilogram for mass, the kelvin for temperature, the pascal for pressure, and so on. A conversion is always performed in two steps: convert the input to the base unit, then convert the base unit to the target.
2. Three kinds of unit relationships
- Linear units use an exact multiplicative factor. For example, one inch is defined as exactly
0.0254metres, so every inch-based conversion derives from that constant rather than a rounded approximation. - Affine units (temperature scales) use a multiplier and an offset, e.g.
°F = °C × 1.8 + 32. We derive these relationships programmatically so the classic formulas are reproduced exactly. - Reciprocal units (such as fuel economy in L/100 km) invert through the base unit so that, for example, kilometres-per-litre and litres-per-100 km round-trip without drift.
3. Exact factors, not rounded constants
Defined conversions — the inch, the pound, the US gallon, the BTU — are stored at full definitional precision. Derived units (for example, litres per minute) are composed from their parts (litres and minutes) so the resulting factor is exact by construction rather than transcribed by hand. This composition approach also means new units cannot introduce rounding errors.
4. Precision and display
Calculations are performed in double-precision floating point. Results are then formatted with adaptive precision: everyday magnitudes are shown with sensible decimal places and thousands separators, while very large or very small results switch to scientific notation. You can adjust the displayed precision up to ten decimal places on any converter; this changes only the display, never the underlying calculation.
5. Review and corrections
Factors are checked against the primary standards listed on oursources page. If you believe a value is wrong, pleasetell us — corrections are prioritised and every report is reviewed against the authoritative definition.