Picometer (pm)

One trillionth of a meter. Atomic diameters are typically a few hundred pm.

1 picometer = 1×10⁻¹² meters (exactly).

ValueFromTo

1 picometer = 1×10⁻¹² meters

About the picometer

One trillionth of a meter, the picometer (pm) is the SI length that sits below the nanometer and above the femtometer. It equals 0.01 angstrom, so a figure in angstroms converts by multiplying by 100. Wikipedia notes that the symbol mu-mu was once used for it, and the NIST list of SI prefixes gives pico as 10 to the power of minus 12.

In practice the unit belongs to chemistry and atomic physics, where distances between bonded atoms are expressed as a few hundred of them. A carbon to carbon single bond is about 154 pm long, and a helium atom is estimated at about 62 pm across, while atoms in general run from roughly 62 to 520 pm in diameter. Chemists who grew up with the angstrom increasingly quote the same distances in picometers, because the angstrom is no longer part of the SI. Gravitational-wave work pushes the scale further: the planned LISA detector is expected to resolve displacements of about 20 pm over a 2.5 million kilometer baseline.

Sources: Wikipedia: Picometre; NIST: metric (SI) prefixes; Wikipedia: Angstrom

Picometer conversion chart

1 picometer expressed in every other length unit:

Unit	1 picometer
Meters	1×10⁻¹²
Kilometers	1×10⁻¹⁵
Centimeters	1×10⁻¹⁰
Millimeters	1×10⁻⁹
Inches	3.937007874×10⁻¹¹
Feet	3.280839895×10⁻¹²
Yards	1.093613298×10⁻¹²
Miles	6.213711922×10⁻¹⁶
Micrometers	0.000001
Nanometers	0.001
Nautical Miles	5.399568035×10⁻¹⁶
Pixels (CSS)	3.779527559×10⁻⁹
Light-years	1.057000834×10⁻²⁸
Femtometers	1,000
Decimeters	1×10⁻¹¹
Hectometers	1×10⁻¹⁴
Decameters	1×10⁻¹³
Thou	3.937007874×10⁻⁸
Points	2.834645669×10⁻⁹
Picas	2.362204724×10⁻¹⁰
Twips	5.669291339×10⁻⁸
Astronomical Units	6.684587122×10⁻²⁴
Light-seconds	3.335640952×10⁻²¹
Light-minutes	5.559401587×10⁻²³
Light-hours	9.265669311×10⁻²⁵
Parsecs	3.240779289×10⁻²⁹
Megaparsecs	3.240779289×10⁻³⁵
Angstroms	0.01
Fathoms	5.468066492×10⁻¹³
Cable Lengths	5.399568035×10⁻¹⁵
Leagues	2.071237307×10⁻¹⁶
Nautical Leagues	1.799856012×10⁻¹⁶
Furlongs	4.970969538×10⁻¹⁵
Chains	4.970969538×10⁻¹⁴
Rods	1.988387815×10⁻¹³
Links	4.970969538×10⁻¹²
Hands	9.842519685×10⁻¹²
Barleycorns	1.181102362×10⁻¹⁰
Palms	1.312335958×10⁻¹¹
Spans	4.374453193×10⁻¹²
Cubits	2.187226597×10⁻¹²
Ells	8.748906387×10⁻¹³
US Survey Feet	3.280833333×10⁻¹²
US Survey Miles	6.213699495×10⁻¹⁶
Stadia	5.208333333×10⁻¹⁵
Roman Inches	4.06504065×10⁻¹¹
Roman Feet	3.378378378×10⁻¹²
Roman Cubits	2.252252252×10⁻¹²
Roman Paces	6.756756757×10⁻¹³
Roman Stadia	5.405405405×10⁻¹⁵
Roman Miles	6.756756757×10⁻¹⁶
Roman Leagues	4.504504505×10⁻¹⁶
Greek Feet	3.125×10⁻¹²
Royal Cubits	1.904761905×10⁻¹²
Egyptian Palms	1.333333333×10⁻¹¹
Egyptian Fingers	5.333333333×10⁻¹¹
Khet	1.904761905×10⁻¹⁴
Biblical Cubits	1.851851852×10⁻¹²
Sabbath Days' Journeys	9.259259259×10⁻¹⁶
Sun	3.3×10⁻¹¹
Shaku	3.3×10⁻¹²
Ken	5.5×10⁻¹³
Jō	3.3×10⁻¹³
Chō	9.166666667×10⁻¹⁵
Ri (Japanese)	2.546296296×10⁻¹⁶
Fen (Chinese)	3×10⁻¹⁰
Cun (Chinese)	3×10⁻¹¹
Chi (Chinese)	3×10⁻¹²
Zhang (Chinese)	3×10⁻¹³
Li (Chinese)	2×10⁻¹⁵
Vershoks	2.249718785×10⁻¹¹
Arshins	1.406074241×10⁻¹²
Sazhens	4.686914136×10⁻¹³
Versts	9.373828271×10⁻¹⁶
Lignes	4.43296×10⁻¹⁰
Pouces	3.694133333×10⁻¹¹
Pieds Du Roi	3.078444444×10⁻¹²
Toises	5.130740741×10⁻¹³
Lieues	2.56537037×10⁻¹⁶
Varas	1.196315349×10⁻¹²
Leguas	1.794473023×10⁻¹⁶
Wa (Thai)	5×10⁻¹³
Sen (Thai)	2.5×10⁻¹⁴
Scandinavian Mil	1×10⁻¹⁶

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