10-^30 10-^45 atto a 10-^18 10-^36 10-^54 Equivalents Units Metric Equivalent US Equivalent acre 0.404 685 64 hectares 43,560 feet^2 acre 4,046,856 4 meters^2 4,840 yards^ 2 acre 0.004 046 856 4 kilometers^2 0.001 562 miles^2,statute are 100 meters^2 119.599 yards^2 barrel (petroleum, US) 158.987 29 liters 42 gallons (proof spirits, US) 151.416 47 liters 0.5 quarts, dry liter 1,000 milliliters 1.056 688 quarts, liquid meter 100
protectorates