Convert Square Meters to Barns - Area Converter
This converter transforms an area expressed in square meters (m²) into barns (b), a unit frequently used in nuclear and particle physics to express cross-sections. The relationship is fixed and exact: one barn equals 1×10⁻²⁸ square meters.
Use this tool for quick conversions, reporting, checking calculations in lab notebooks, or preparing figures and tables. Results are suitable for engineering and research workflows when you account for appropriate significant figures and instrument resolution.
Values and guidance here follow internationally recognized references for units and physical constants to ensure traceability and reproducibility in scientific and regulatory contexts.
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Methodology
The conversion factor comes from the accepted physics definition: 1 barn = 1×10⁻²⁸ m². This is an exact scaling factor used in nuclear and particle physics literature and reference databases.
We apply a straightforward multiplicative conversion (no approximations) and display results with configurable rounding in the UI. For lab-grade reporting, match the displayed significant figures to instrument uncertainty and experimental error budgets.
When using converted values in publications or compliance documents, reference authoritative sources for units and constants (for example, national metrology institutes and international SI publications).
Worked examples
Example 1: 1 m² → 1 × 10²⁸ barns.
Example 2: 0.000001 m² (1 μm²) → 1 × 10²² barns.
Further resources
External guidance
Expert Q&A
What is the exact conversion factor between square meters and barns?
Exactly 1 barn = 1 × 10⁻²⁸ square meters, so multiply square meters by 1 × 10²⁸ to get barns.
When should I use barns instead of square meters?
Barns are used primarily for microscopic cross-sectional areas in nuclear and particle physics. For macroscopic engineering or architectural work, square meters remain the standard SI area unit.
How many significant figures should I show after converting?
Match the number of significant figures to your measurement uncertainty or instrument resolution. The converter provides full-precision results; round only to reflect experimental or reporting accuracy.
Is the barn an SI unit?
The barn is not an SI base unit but is a conventional unit used in physics. Its value is defined with respect to the SI unit of area (square meter) and is widely accepted in the scientific literature.
Can I convert very large or very small values safely?
Yes. This conversion is a simple fixed-scale multiplication. For extremely large exponents, be mindful of display/precision limits in your browser or downstream software and use scientific notation when necessary.
Where does the conversion factor come from and how can I cite it?
The factor is defined by physics references and metrology authorities. For formal citations, refer to national metrology publications and the SI Brochure from the Bureau International des Poids et Mesures (BIPM) or NIST unit listings.
Sources & citations
- NIST - Units and Symbols for Conserved Quantities / Unit pages — https://physics.nist.gov/cuu/Units/barn.html
- BIPM - The International System of Units (SI Brochure) — https://www.bipm.org/en/publications/si-brochure
- MIT OpenCourseWare - Open educational resource for physics and measurements — https://ocw.mit.edu
- Particle Data Group (reference resource for particle physics data) — https://pdg.lbl.gov