Convert Barn to Millibarn
Convert barns to millibarns instantly. 1 barn = 1000 millibarn — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Millibarn 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.
Millibarn
A millibarn is a scientific unit of area equal to exactly 10⁻³¹ m² (1/1000 of a barn).
Derived from the barn using the standard SI milli- prefix.
Millibarns are widely used in particle physics for medium-strength interaction cross-sections. The total proton-proton inelastic cross-section is on the order of 70 mb at LHC energies.
Standard derivative of the barn unit.
Barn to Millibarn conversion formula
The relationship between barns and millibarns:
To convert barns to millibarns, multiply the value in barns by 1000. To reverse, multiply millibarns by 0.001.
How to use this converter
Type a value into the calculator. The result in millibarns updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Millibarn to Barn converter for the reverse direction.
Step-by-step: convert barns to millibarns
- Write down the value in barns (b).
- Multiply that value by the factor 1000.
- The product is the equivalent value in millibarns (mb).
- To reverse, multiply the millibarn value by 0.001.
Worked examples
Example 1 — Convert 1 b to mb:
1 × 1000 = 1000 mb
Example 2 — Convert 100 b to mb:
100 × 1000 = 100000 mb
Real-world example — Molecular dimensions
The diameter of small molecular structures (around 2 barns) is often converted into related sub-micron units when comparing measurements across different microscopy techniques or imaging modalities.
2 b × 1000 = 2000 mb
Real-world example — Wavelengths across the spectrum
Optical and atomic-scale phenomena are routinely cross-converted between sub-micron units. A photon of wavelength 800 barns can be re-expressed in millibarns for direct comparison with another instrument's calibration data sheet.
800 b × 1000 = 799999.9999999999 mb
Barn to Millibarn conversion table
Standard reference values for converting barns to millibarns:
| Barn [b] | Millibarn [mb] |
|---|---|
| 0.01 | 10 |
| 0.1 | 100 |
| 1 | 1000 |
| 2 | 2000 |
| 3 | 3000 |
| 4 | 4000 |
| 5 | 5000 |
| 10 | 10000 |
| 20 | 20000 |
| 30 | 30000 |
| 40 | 40000 |
| 50 | 50000 |
| 100 | 100000 |
| 500 | 499999.9999999999 |
| 1000 | 999999.9999999999 |
Frequently asked questions
How many millibarns is 1 barn?
How do I convert barns to millibarns?
How do I convert millibarns back to barns?
How many millibarns is 100 barns?
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Sources & references
Conversion factor (1 b = 1000 mb) 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.