RPM to KMH Converter

The RPM to KMH Converter computes vehicle speed in km/h from wheel rotational rate. It accepts wheel RPM and wheel size and returns a precise speed estimate suitable for engineering, testing, and educational use. The core assumption is that RPM refers to wheel RPM and that the wheel circumference is known via diameter or directly provided.
The tool supports two input methods: provide rpm and wheel_diameter_cm, or provide rpm and wheel_circumference_cm. If circumference is omitted, the tool derives it from pi times the diameter. This yields an exact linear speed in km/h under the stated assumptions; it does not account for drivetrain gear ratios, tire slip, or deformation.
Common use cases include drivetrain testing, vehicle dynamics analysis, and engineering prototyping where a quick speed estimate is needed from measured RPM. The unique value lies in combining both direct circumference input and diameter-based derivation in a single calculation, with clear validation rules and unit-consistent outputs. Core features include input validation, fallback calculations, and a precise formula for speed that is easy to audit and reproduce. Use cases span automotive labs, hobbyist testing, and educational demonstrations of rotational-to-linear speed relationships.