Convert Barn to Square Inch
Convert barns to square inches instantly. 1 barn = 1.550003e-25 square inch — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Square Inch 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 Inch
A square inch is an imperial unit of area equal to exactly 0.00064516 m², the area of a square with sides of one inch. It is widely used in the United States for small-area measurements.
Derived by squaring the inch. The inch was standardized to exactly 25.4 mm via the 1959 International Yard and Pound Agreement.
Square inches are used extensively in US engineering, manufacturing, real estate (for floor plans), and everyday small-area measurements. Engine displacement is often expressed in cubic inches but cross-sections in square inches.
Inch dates to medieval English usage; modern exact value standardized in 1959.
Barn to Square Inch conversion formula
The relationship between barns and square inches:
To convert barns to square inches, multiply the value in barns by 1.550003e-25. To reverse, multiply square inches by 6.4516e+24.
How to use this converter
Type a value into the calculator. The result in square inches 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 Inch to Barn converter for the reverse direction.
Step-by-step: convert barns to square inches
- Write down the value in barns (b).
- Multiply that value by the factor 1.550003e-25.
- The product is the equivalent value in square inches (in²).
- To reverse, multiply the square inch value by 6.4516e+24.
Worked examples
Example 1 — Convert 1 b to in²:
1 × 1.550003e-25 = 1.550003e-25 in²
Example 2 — Convert 100 b to in²:
100 × 1.550003e-25 = 1.550003e-23 in²
Real-world example — Sub-visible-light wavelength
500 barns (the green-yellow visible band) equals 0.5 square inches — the canonical conversion in optics between wavelength specifications and micron-scale lens-coating thicknesses.
500 b × 1.550003e-25 = 7.750016e-23 in²
Real-world example — Spanning sub-micron to micron scale
Crossing from barns to square inches is the everyday workflow of microscopy and semiconductor engineering — a measurement of 1000 barns translates to a much more compact value in square inches that fits the scale of biological cells and process nodes.
1000 b × 1.550003e-25 = 1.550003e-22 in²
Barn to Square Inch conversion table
Standard reference values for converting barns to square inches:
| Barn [b] | Square Inch [in²] |
|---|---|
| 0.01 | 1.550003e-27 |
| 0.1 | 1.550003e-26 |
| 1 | 1.550003e-25 |
| 2 | 3.100006e-25 |
| 3 | 4.650009e-25 |
| 4 | 6.200012e-25 |
| 5 | 7.750016e-25 |
| 10 | 1.550003e-24 |
| 20 | 3.100006e-24 |
| 30 | 4.650009e-24 |
| 40 | 6.200012e-24 |
| 50 | 7.750016e-24 |
| 100 | 1.550003e-23 |
| 500 | 7.750016e-23 |
| 1000 | 1.550003e-22 |
Frequently asked questions
How many square inches is 1 barn?
How do I convert barns to square inches?
How do I convert square inches back to barns?
How many square inches is 100 barns?
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Metric / SI (5 units)
Imperial / US Customary (3 units)
Scientific / Physics (4 units)
Sources & references
Conversion factor (1 b = 1.550003e-25 in²) 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 Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.