Square metric area unit.
Square Millimeters to Barns Converter — mm2 to b
Convert Square Millimeter (mm2) to Barn (b) using the exact conversion factor (1 square millimeter = 1e+22 barn). See the formula, worked examples, and conversion table.
Square Millimeters to Barns converter
Converter
Area Converter
Convert land, construction, mapping, survey, and scientific area units.
Context values
Some unit families need one extra value for a physically accurate result.
A barn is a nuclear cross-section unit equal to 1e-28 square meters.
Result = input x 1e-6 / 1e-28.
Area uses the square meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Square Millimeters to Barns
Comparing Square Millimeter and Barn is common in agriculture and real estate, where US land is typically measured in acres and most of the rest of the world uses hectares. Specifically: Square metric area unit, and a barn is a nuclear cross-section unit equal to 1e-28 square meters.
Formula
barns = square millimeters × 1e+22
This factor comes from each unit's defined relationship to the category's base unit: 1 square millimeter equals 0.000001 base units, and 1 barn equals 1e-28 base units, so dividing one by the other gives the direct square millimeter-to-barn factor of 1e+22.
Simple example
1 mm2 × 1e+22 = 1e+22 b
1 square millimeter = 1e+22 barns.
Real-world example
10 mm2 × 1e+22 = 1e+23 b
10 square millimeters = 1e+23 barns.
Conversion table
| Square Millimeter (mm2) | Barn (b) |
|---|---|
| 1 mm2 | 1e+22 b |
| 5 mm2 | 5e+22 b |
| 10 mm2 | 1e+23 b |
| 25 mm2 | 2.5e+23 b |
| 50 mm2 | 5e+23 b |
| 100 mm2 | 1e+24 b |
Reverse conversion: Barn to Square Millimeter
1e+22 b × 1e-22 = 1 mm2
1e+22 barns = 1 square millimeter.
square millimeters = barns × 1e-22
For a page dedicated to this direction, see Barn to Square Millimeter.
Understanding the Square Millimeter (mm2)
Square metric area unit.
Understanding the Barn (b)
A barn is a nuclear cross-section unit equal to 1e-28 square meters.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many barns are in 1 square millimeter?
1 square millimeter equals 1e+22 barns, using the exact defined conversion factor rather than an estimate.
How do I convert square millimeter to barn?
Multiply the square millimeter value by 1e+22. The converter above does this instantly to whatever precision you set.
How do I convert barn back to square millimeter?
Use the reverse factor: 1 barn equals 1e-22 square millimeters. You can also use the swap control in the converter above to flip the direction instantly.
What is a square millimeter?
Square Millimeter (mm2) is a unit of area.
What is a barn?
Barn (b) is a unit of area.
Is the square millimeter to barn conversion exact?
Yes. Both square millimeter and barn are defined by fixed standards rather than physical artifacts, so the factor of 1e+22 used above is exact to as many digits as you choose to display.