Inches to Picometers (in to pm)

1 inch equals 25,400,000,000 picometers exactly.

1 inch = 25,400,000,000 picometers

How to convert inches to picometers

To convert inches to picometers, multiply the number of inches by 25,400,000,000. This factor is exact. To go the other way, multiply picometers by 3.937007874×10⁻¹¹ (rounded).

picometers = inches × 25,400,000,000

Example: 10 inches = 254,000,000,000 picometers.

About these units

Inch (in)

US & ImperialCurrent unit

1/12 of a foot. Defined as exactly 25.4 millimeters since 1959, when the US and Commonwealth countries agreed a common international inch.

Latin uncia, meaning one-twelfth, is the root of both inch and ounce, and it passed into Old English as ynce. Roman measurers divided their foot into twelve unciae, and the English inch kept that twelfth. After 1066 an inch was reckoned as three barleycorns, and a 1324 statute attributed to Edward II spelled out the definition as three grains of barley, dry and round, placed end to end lengthwise. For centuries the inch was simply a twelfth of a foot, or a thirty-sixth of a yard, and the US and UK each kept their own copy of the standard yard.

Those copies differed slightly until the 1959 international agreement fixed the yard at exactly 0.9144 meter, which made the inch exactly 25.4 millimeters. The US adopted it in 1959 and the UK ratified it in 1963, effective 1964. Today the inch is still the customary unit in the United States and Canada, and the UK keeps it on road signs. Worldwide it also names display diagonals, wheel rims, tire codes and pipe sizes.

1 inch = 0.0254 meters (exactly).

Sources: Wikipedia: Inch; Wikipedia: Yard; NIST Guide to the SI, Appendix B.8: conversion factors

Picometer (pm)

Metric (SI)Current unit

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

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.

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

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

Related conversions

See all length units.