Convert Square Millimeters to Barns
Convert Square Millimeters (mm²) to Barns (b) instantly and accurately.
Conversion Formula
b = mm² × 1.000000000e+22
About Square Millimeters
A square millimeter (mm²) is a metric unit of area equal to a square with sides of one millimeter. It is commonly used in precision engineering, electronics, and measuring very small surfaces such as microchips or printed circuit boards. To visualise: a typical pinhead has an area of about 2-3 mm². This unit is essential in microscopy, medical imaging, and manufacturing where tiny, precise measurements are critical.
About Barns
A barn (b) is a unit of area used in nuclear and particle physics to measure effective cross-sections of atomic nuclei and particle interaction probabilities. Equal to 10⁻²⁸ m² (10⁻²⁴ cm²), it was humorously named during the Manhattan Project - physicists joked that uranium nuclei were 'as big as a barn' at the subatomic scale. Particle physics experiments at accelerators like CERN report cross-sections in millibarns (mb), microbarns (μb), nanobarns (nb), and femtobarns (fb).
Quick Reference Table
| Square Millimeters (mm²) | Barns (b) |
|---|---|
| 1 mm² | 1 × 1022 b |
| 2 mm² | 2 × 1022 b |
| 5 mm² | 5 × 1022 b |
| 10 mm² | 1 × 1023 b |
| 25 mm² | 2.5 × 1023 b |
| 50 mm² | 5 × 1023 b |
| 100 mm² | 1 × 1024 b |