The angstrom equals 10⁻¹⁰ meters or 0.1 nanometers. It is used in chemistry and crystallography for atomic and molecular dimensions. The Bohr radius — the characteristic size of a hydrogen atom — is 0.529 Å. Covalent bond lengths are typically 1–2 Å.
Real-world: A water molecule is about 1 Å across. The covalent bond in H₂ is 0.74 Å. X-ray wavelengths are 0.1–100 Å.
Read full angstrom reference →The yard equals 0.9144 meters exactly, or 3 feet. It is the standard field unit in American football (100-yard field) and British cricket (22-yard pitch). Fabric and textile in Anglo-Saxon countries is still sold by the yard. Historically the yard was said to be the length of King Henry I of England's arm.
Real-world: An NFL football field is 100 yards = 91.44 metres. A cricket pitch is 22 yards = 20.12 metres.
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