Dimensional metrology —the measurement of dimensions, size, shape, form, texture, location— is a fundamental requirement for any manufacturing and trading economy. The SI unit of length, the metre, has recently been re-defined based on the speed of light, c. However the traceability route from c to practical measurements throughout all application fields is far from simple. This paper describes the traceability routes and solutions employed throughout the length scale, from nm to km, to deliver length metrology with traceability to the SI in a wide range of settings, from laboratory to factory.