// conversions › 1 · Basic Converters
Convert length between metric, imperial and astronomical units — nanometres to light-years — via the metre.
result = value × (from→metre) ÷ (to→metre)
It converts convert length between metric, imperial and astronomical units — nanometres to light-years — via the metre by first normalising your value to the SI base unit (metre) and then scaling to your chosen target unit. This hub-and-spoke approach guarantees every unit pair is internally consistent.
100 metres to feet: 100 × 1 = 100 m (base), then 100 ÷ 0.3048 ≈ 328.08 ft.
Metric units step in powers of ten (1 km = 1000 m), so factors are round. Imperial units were pinned to the metre later, giving exact but odd factors like 1 mile = 1609.344 m. Both are exact; only the numbers look different.
Engineering drawings, navigation (nmi), astronomy (AU, light-years) and everyday DIY.
Conversions are exact ratios where the units are defined exactly (most SI and imperial units) and best-available constants otherwise. Extremely large or small magnitudes are shown in general (g) format; round-tripping through the base unit may introduce tiny floating-point differences in the final decimal places.