Convert Chain (ch) to Picometer (pm) instantly.
About these units
Chain (ch)
A chain is equal to 66 feet or 4 rods, and it was standardized by surveyor Edmund Gunter in the 17th century. "Gunter's chain," consisting of 100 metal links, became the backbone of land surveying in the English-speaking world for centuries. Its convenience stems from simple arithmetic: 10 square chains make an acre, making land area calculations straightforward. Railroads, farmland, and city parcels across the United States and the Commonwealth nations were once laid out using chains, so the unit appears in countless historical records. Even today, some legal property descriptions still reference chain-based measurements, making the unit relevant for modern surveyors who interpret old maps. Although high-precision digital equipment has replaced physical chains, the unit's structural role in land division ensures its lasting importance.
Picometer (pm)
At 10⁻¹² meters, the picometer occupies a scale close to the dimensions of atoms but slightly finer than typical atomic radii. Chemists use picometers to express covalent bond lengths, ionic radii, and atomic radii. For example, the radius of a hydrogen atom is about 53 pm. The unit also appears frequently in crystallography, where X-ray diffraction reveals lattice spacing on the order of a few hundred picometers. The picometer provides a numeric convenience: atomic structures are neither too large nor too small to measure accurately in this unit. In physics, picometer-scale distances become relevant when examining the interactions of electrons in tightly bound orbitals or in high-resolution measurements of electric dipole moments. It is a unit that bridges atomic size with the precision of modern measurement tools.