Convert Barn to Square Meter
Convert barns to square meters instantly. 1 barn = 1e-28 square meter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Square Meter to Barn converter for the reverse conversion.
Units explained
Barn
A barn is a scientific unit of area equal to exactly 10⁻²⁸ m² (100 fm²). It is used in nuclear and particle physics to express interaction cross-sections.
Named in 1942 at Purdue University by physicists working on the Manhattan Project. The name comes from the phrase 'big as a barn' — uranium nuclei have cross-sections this large, which physicists initially considered surprisingly large for nuclear targets.
Barns and their submultiples (millibarn, microbarn, nanobarn, picobarn, femtobarn) are the standard units for cross-section measurements in nuclear physics, high-energy physics, and accelerator experiments. The Higgs boson production cross-section at the LHC is in the picobarn range.
Named in 1942 during the Manhattan Project; adopted internationally in particle physics.
Square Meter
A square meter is the SI base unit of area, defined as the area of a square with sides of one meter. It is the universal scientific unit for area.
Defined by squaring the meter, which was redefined in 2019 in terms of the speed of light. The meter itself was originally proposed by the French Academy of Sciences in 1791 as 1/10,000,000 of the distance from the equator to the North Pole.
Square meters are the universal SI unit for area, used in real estate (most countries outside the US/UK), construction, physics, engineering, materials science, biology, and nearly all scientific contexts worldwide.
Meter adopted as SI base unit in 1960; current exact definition via speed of light dates to 2019.
Barn to Square Meter conversion formula
The relationship between barns and square meters:
To convert barns to square meters, multiply the value in barns by 1e-28. To reverse, multiply square meters by 1e+28.
How to use this converter
Type a value into the calculator. The result in square meters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Square Meter to Barn converter for the reverse direction.
Step-by-step: convert barns to square meters
- Write down the value in barns (b).
- Multiply that value by the factor 1e-28.
- The product is the equivalent value in square meters (m²).
- To reverse, multiply the square meter value by 1e+28.
Worked examples
Example 1 — Convert 1 b to m²:
1 × 1e-28 = 1e-28 m²
Example 2 — Convert 100 b to m²:
100 × 1e-28 = 1e-26 m²
Real-world example — Bridging nine orders of magnitude
500 million barns equals a value comfortably in the human-scale square meters range. Physics problems that span this gap are common when comparing the wavelength of light to the path length of an experiment.
5e+8 b × 1e-28 = 5e-20 m²
Real-world example — From sub-micron to human scale
One billion barns equals one square meter — the conversion that drives home the gulf between atomic-scale features and everyday objects in physics curricula.
1e+9 b × 1e-28 = 1e-19 m²
Barn to Square Meter conversion table
Standard reference values for converting barns to square meters:
| Barn [b] | Square Meter [m²] |
|---|---|
| 0.01 | 1e-30 |
| 0.1 | 1e-29 |
| 1 | 1e-28 |
| 2 | 2e-28 |
| 3 | 3e-28 |
| 4 | 4e-28 |
| 5 | 5e-28 |
| 10 | 1e-27 |
| 20 | 2e-27 |
| 30 | 3e-27 |
| 40 | 4e-27 |
| 50 | 5e-27 |
| 100 | 1e-26 |
| 500 | 5e-26 |
| 1000 | 1e-25 |
Frequently asked questions
How many square meters is 1 barn?
How do I convert barns to square meters?
How do I convert square meters back to barns?
How many square meters is 100 barns?
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Sources & references
Conversion factor (1 b = 1e-28 m²) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.