Square Feet to Barns (ft² to b)

1 square foot equals 9.290304×10²⁶ barns exactly.

1 square foot = 9.290304×10²⁶ barns

How to convert square feet to barns

To convert square feet to barns, multiply the number of square feet by 9.290304×10²⁶. This factor is exact. To go the other way, multiply barns by 1.076391042×10⁻²⁷ (rounded).

barns = square feet × 9.290304×10²⁶

Example: 10 square feet = 9.290304×10²⁷ barns.

About these units

Square Foot (ft²)

US & ImperialCurrent unit

Exactly 0.09290304 m². The standard unit for floor areas and real estate in the US, UK and India.

Feet came first, and they were not all the same length. As a body-based unit, the foot ranged historically between about 250 and 335 millimeters, with ancient Greek and Roman feet near 300 mm. In medieval England a statute foot was set at 10/11 of an older Belgic foot, and Charlemagne's attempt around 790 to standardize units largely failed. The square foot is simply that length squared, so its size changed along with the foot.

The 1959 international agreement fixed the foot at exactly 0.3048 meter, so one square foot is exactly 0.09290304 m², or 144 square inches. The United Kingdom adopted the new foot in 1964. Today the square foot is the usual way of listing property in the United States, Canada, the United Kingdom, India, Pakistan, Singapore and Hong Kong, although the measuring convention varies: agents may measure corner to corner, subtract unheated space, or add heated space that extends beyond the end-to-end measurement. The world's smallest park has been reported at 2.6 sq ft.

1 square foot = 0.09290304 square meters (exactly).

Sources: Wikipedia: Square foot; Wikipedia: Foot (unit); NIST Guide to the SI, Appendix B.8: conversion factors

Barn (b)

ScientificCurrent unit

Exactly 10⁻²⁸ square meters. Used in nuclear and particle physics for reaction cross-sections; the name is a joke about a target 'as big as a barn'.

Nuclear physicists coined this unit during the Second World War. Marshall Holloway and Charles Baker, working at Purdue on Manhattan Project problems, wanted a short name for the cross section of a nucleus and passed over names such as Oppenheimer and Bethe. They settled on a joke about a target that was really as big as a barn, and the word first appeared in print in a secret Los Alamos report of June 1943.

One barn is 10 to the power of minus 28 square meters, or 100 square femtometers, roughly the cross-sectional area of a uranium nucleus. NIST lists the conversion as exact. The barn was never an SI unit, though the BIPM acknowledged it in the eighth SI Brochure because particle physics relies on it. Prefixed forms dominate today: the femtobarn is the usual choice in high-energy physics, and the inverse femtobarn measures integrated luminosity. Informal names exist too, such as outhouse for a microbarn and shed for a yoctobarn.

1 barn = 1×10⁻²⁸ square meters (exactly).

Sources: Wikipedia: Barn (unit); NIST SP 811, Appendix B.8 conversion factors

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