Angstrom (Å)

ScientificTraditional unit (still used in some regions)

One ten-billionth of a meter (0.1 nm). Named after Anders Ångström and used for atomic and molecular sizes and bond lengths.

1 angstrom = 1×10⁻¹⁰ meters (exactly).

1 angstrom = 1×10⁻¹⁰ meters

About the angstrom

Swedish physicist Anders Jonas Angstrom (1814-1874) charted the solar spectrum in 1868 in multiples of one ten-millionth of a millimeter, and solar physicists later named that interval after him. It equals 10 to the minus 10 meter, 0.1 nanometer or 100 picometers. Atoms and bonds fit it well: hydrogen is about 0.5 angstrom in covalent radius, and visible light spans roughly 4000 to 7000 angstroms.

The unit's size was not always exact. In 1907 the International Angstrom was fixed as 1/6438.4696 of the cadmium red line wavelength, a definition the 7th CGPM endorsed in 1927. The 1960 redefinition of the meter by a spectral line made it exactly 10 to the minus 10 meter, and NIST lists the conversion as exact. A later X-ray version, the angstrom star of 1965, was obsolete within about ten years. The unit was listed as acceptable by NIST and BIPM until 2019 but is absent from the 9th SI Brochure, and nanometers and picometers are slowly replacing it.

Sources: Wikipedia: Angstrom; NIST Guide to the SI, Appendix B.8; Wikipedia: Picometre

Angstrom conversion chart

1 angstrom expressed in every other length unit:

Unit1 angstrom
Meters1×10⁻¹⁰
Kilometers1×10⁻¹³
Centimeters1×10⁻⁸
Millimeters1×10⁻⁷
Inches3.937007874×10⁻⁹
Feet3.280839895×10⁻¹⁰
Yards1.093613298×10⁻¹⁰
Miles6.213711922×10⁻¹⁴
Micrometers0.0001
Nanometers0.1
Nautical Miles5.399568035×10⁻¹⁴
Pixels (CSS)3.779527559×10⁻⁷
Light-years1.057000834×10⁻²⁶
Picometers100
Femtometers100,000
Decimeters1×10⁻⁹
Hectometers1×10⁻¹²
Decameters1×10⁻¹¹
Thou0.000003937007874
Points2.834645669×10⁻⁷
Picas2.362204724×10⁻⁸
Twips0.000005669291339
Astronomical Units6.684587122×10⁻²²
Light-seconds3.335640952×10⁻¹⁹
Light-minutes5.559401587×10⁻²¹
Light-hours9.265669311×10⁻²³
Parsecs3.240779289×10⁻²⁷
Megaparsecs3.240779289×10⁻³³
Fathoms5.468066492×10⁻¹¹
Cable Lengths5.399568035×10⁻¹³
Leagues2.071237307×10⁻¹⁴
Nautical Leagues1.799856012×10⁻¹⁴
Furlongs4.970969538×10⁻¹³
Chains4.970969538×10⁻¹²
Rods1.988387815×10⁻¹¹
Links4.970969538×10⁻¹⁰
Hands9.842519685×10⁻¹⁰
Barleycorns1.181102362×10⁻⁸
Palms1.312335958×10⁻⁹
Spans4.374453193×10⁻¹⁰
Cubits2.187226597×10⁻¹⁰
Ells8.748906387×10⁻¹¹
US Survey Feet3.280833333×10⁻¹⁰
US Survey Miles6.213699495×10⁻¹⁴
Stadia5.208333333×10⁻¹³
Roman Inches4.06504065×10⁻⁹
Roman Feet3.378378378×10⁻¹⁰
Roman Cubits2.252252252×10⁻¹⁰
Roman Paces6.756756757×10⁻¹¹
Roman Stadia5.405405405×10⁻¹³
Roman Miles6.756756757×10⁻¹⁴
Roman Leagues4.504504505×10⁻¹⁴
Greek Feet3.125×10⁻¹⁰
Royal Cubits1.904761905×10⁻¹⁰
Egyptian Palms1.333333333×10⁻⁹
Egyptian Fingers5.333333333×10⁻⁹
Khet1.904761905×10⁻¹²
Biblical Cubits1.851851852×10⁻¹⁰
Sabbath Days' Journeys9.259259259×10⁻¹⁴
Sun3.3×10⁻⁹
Shaku3.3×10⁻¹⁰
Ken5.5×10⁻¹¹
Jō3.3×10⁻¹¹
Chō9.166666667×10⁻¹³
Ri (Japanese)2.546296296×10⁻¹⁴
Fen (Chinese)3×10⁻⁸
Cun (Chinese)3×10⁻⁹
Chi (Chinese)3×10⁻¹⁰
Zhang (Chinese)3×10⁻¹¹
Li (Chinese)2×10⁻¹³
Vershoks2.249718785×10⁻⁹
Arshins1.406074241×10⁻¹⁰
Sazhens4.686914136×10⁻¹¹
Versts9.373828271×10⁻¹⁴
Lignes4.43296×10⁻⁸
Pouces3.694133333×10⁻⁹
Pieds Du Roi3.078444444×10⁻¹⁰
Toises5.130740741×10⁻¹¹
Lieues2.56537037×10⁻¹⁴
Varas1.196315349×10⁻¹⁰
Leguas1.794473023×10⁻¹⁴
Wa (Thai)5×10⁻¹¹
Sen (Thai)2.5×10⁻¹²
Scandinavian Mil1×10⁻¹⁴

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