Convert Fathom (fath) to Petameter (Pm) instantly.
About these units
Fathom (fath)
A fathom is equal to 6 feet and is historically associated with maritime measurement. Its origins may lie in the approximate span of a fully outstretched human arms, which was convenient for measuring rope lengths by hand aboard ships. Sailors used the fathom to estimate water depth through weighted lines, giving rise to the practice of "sounding" the depths. The fathom became a cornerstone unit in nautical life because it fits the human scale while also being large enough to measure significant underwater distances. Charts, sonar readings, and older depth gauges frequently utilized fathoms, although modern equipment increasingly displays depths in meters. Still, many mariners—particularly in regions using imperial measurements—continue to think instinctively in fathoms when estimating safe anchoring or navigating shallow waters. The unit persists as an important piece of maritime history and remains in active use by traditional sailors, divers, and some fishing industries. Its survival reflects the enduring cultural heritage of nautical practice.
Petameter (Pm)
A petameter is 10¹⁵ meters and begins bridging the gap between solar system scales and the nearest stars. Distances between stars, the size of large cosmic structures, or the wavelengths of extremely low-frequency electromagnetic waves may be expressed in petameters. For example, a light-year is about 9.46 petameters. Petameters rarely appear in everyday astronomical writing because traditional units like light years and parsecs are more intuitive to astronomers and the public. However, the unit's alignment with SI conventions makes it essential in scientific computation and large-scale modeling, especially when dealing with cosmic distances while maintaining strictly metric consistency.