How big is an acre in terms of kilometers?

Answer 1

an acre is a measure of area whereas a kilometer is a measure of length, but a square kilometer is a measure of area, so I'll presume you meant square kilometers.

1 acre is approx 1/250 sq km = 0.004 sq km.

1 acre = 1/640 sq mile

1 mile ≈ 8/5 km

1 sq mi = 1 mi x 1 mi ≈ 8/5 km x 8/5 km = 64/25 sq km

→1 acre = 1/640 sq mi ≈ 1/640 x 64/25 sq km = 1/250 sq km = 0.004 sq km

Answer 2

One acre is equal to approximately 0.004 square kilometers.