0.00000000000000000000000000000000010000000000000001 km2
1 b (barn) is equal to 0.00000000000000000000000000000000010000000000000001 km2 (square kilometer). To convert from barn to square kilometer, multiply by 0.0000000000000000000000000000000001 or divide by 10,000,000,000,000,001,000,000,000,000,000,000.