| 0b | 0km² |
| 1b | 1 × 10⁻³⁴km² |
| 2b | 2 × 10⁻³⁴km² |
| 3b | 3 × 10⁻³⁴km² |
| 4b | 4 × 10⁻³⁴km² |
| 5b | 5 × 10⁻³⁴km² |
| 6b | 6 × 10⁻³⁴km² |
| 7b | 7 × 10⁻³⁴km² |
| 8b | 8 × 10⁻³⁴km² |
| 9b | 9 × 10⁻³⁴km² |
| 10b | 1 × 10⁻³³km² |
| 11b | 1.1 × 10⁻³³km² |
| 12b | 1.2 × 10⁻³³km² |
| 13b | 1.3 × 10⁻³³km² |
| 14b | 1.4 × 10⁻³³km² |
| 15b | 1.5 × 10⁻³³km² |
| 16b | 1.6 × 10⁻³³km² |
| 17b | 1.7 × 10⁻³³km² |
| 18b | 1.8 × 10⁻³³km² |
| 19b | 1.9 × 10⁻³³km² |
| 20b | 2 × 10⁻³³km² |
| 21b | 2.1 × 10⁻³³km² |
| 22b | 2.2 × 10⁻³³km² |
| 23b | 2.3 × 10⁻³³km² |
| 24b | 2.4 × 10⁻³³km² |
| 25b | 2.5 × 10⁻³³km² |
| 26b | 2.6 × 10⁻³³km² |
| 27b | 2.7 × 10⁻³³km² |
| 28b | 2.8 × 10⁻³³km² |
| 29b | 2.9 × 10⁻³³km² |
| 30b | 3 × 10⁻³³km² |
| 31b | 3.1 × 10⁻³³km² |
| 32b | 3.2 × 10⁻³³km² |
| 33b | 3.3 × 10⁻³³km² |
| 34b | 3.4 × 10⁻³³km² |
| 35b | 3.5 × 10⁻³³km² |
| 36b | 3.6 × 10⁻³³km² |
| 37b | 3.7 × 10⁻³³km² |
| 38b | 3.8 × 10⁻³³km² |
| 39b | 3.9 × 10⁻³³km² |
| 40b | 4 × 10⁻³³km² |
| 41b | 4.1 × 10⁻³³km² |
| 42b | 4.2 × 10⁻³³km² |
| 43b | 4.3 × 10⁻³³km² |
| 44b | 4.4 × 10⁻³³km² |
| 45b | 4.5 × 10⁻³³km² |
| 46b | 4.6 × 10⁻³³km² |
| 47b | 4.7 × 10⁻³³km² |
| 48b | 4.8 × 10⁻³³km² |
| 49b | 4.9 × 10⁻³³km² |
| 50b | 5 × 10⁻³³km² |
| 51b | 5.1 × 10⁻³³km² |
| 52b | 5.2 × 10⁻³³km² |
| 53b | 5.3 × 10⁻³³km² |
| 54b | 5.4 × 10⁻³³km² |
| 55b | 5.5 × 10⁻³³km² |
| 56b | 5.6 × 10⁻³³km² |
| 57b | 5.7 × 10⁻³³km² |
| 58b | 5.8 × 10⁻³³km² |
| 59b | 5.9 × 10⁻³³km² |
| 60b | 6 × 10⁻³³km² |
| 61b | 6.1 × 10⁻³³km² |
| 62b | 6.2 × 10⁻³³km² |
| 63b | 6.3 × 10⁻³³km² |
| 64b | 6.4 × 10⁻³³km² |
| 65b | 6.5 × 10⁻³³km² |
| 66b | 6.6 × 10⁻³³km² |
| 67b | 6.7 × 10⁻³³km² |
| 68b | 6.8 × 10⁻³³km² |
| 69b | 6.9 × 10⁻³³km² |
| 70b | 7 × 10⁻³³km² |
| 71b | 7.1 × 10⁻³³km² |
| 72b | 7.2 × 10⁻³³km² |
| 73b | 7.3 × 10⁻³³km² |
| 74b | 7.4 × 10⁻³³km² |
| 75b | 7.5 × 10⁻³³km² |
| 76b | 7.6 × 10⁻³³km² |
| 77b | 7.7 × 10⁻³³km² |
| 78b | 7.8 × 10⁻³³km² |
| 79b | 7.9 × 10⁻³³km² |
| 80b | 8 × 10⁻³³km² |
| 81b | 8.1 × 10⁻³³km² |
| 82b | 8.2 × 10⁻³³km² |
| 83b | 8.3 × 10⁻³³km² |
| 84b | 8.4 × 10⁻³³km² |
| 85b | 8.5 × 10⁻³³km² |
| 86b | 8.6 × 10⁻³³km² |
| 87b | 8.7 × 10⁻³³km² |
| 88b | 8.8 × 10⁻³³km² |
| 89b | 8.9 × 10⁻³³km² |
| 90b | 9 × 10⁻³³km² |
| 91b | 9.1 × 10⁻³³km² |
| 92b | 9.2 × 10⁻³³km² |
| 93b | 9.3 × 10⁻³³km² |
| 94b | 9.4 × 10⁻³³km² |
| 95b | 9.5 × 10⁻³³km² |
| 96b | 9.6 × 10⁻³³km² |
| 97b | 9.7 × 10⁻³³km² |
| 98b | 9.8 × 10⁻³³km² |
| 99b | 9.9 × 10⁻³³km² |
The barn is a unit of area and is used in particle physics with the symbol b.
It represents approximately the area of the cross-section of a uraneum nucleus, so is very small compared to most other recognised units of area.
It is also used to measure the interaction of a nucleus with an electric field gradient in nuclear quadrupole and magnetic resonance.
The square kilometre is a unit of area and is a multiple of the square metre; an SI derived unit. It has the symbol km².
A square kilometre is equal to the area of a square with edges 1km long. There are 1,000,000 square metres in a square kilometre.
Square kilometres are often used to describe expansive areas of land due to the large unit size.