How Many Football Fields Would the Monarchs Cover? Example: Using the 2010/2011 population estimate of 4.02 hectares, here is our calculation: 1 football field is roughly 1 acre. (The exact measurements of football fields vary.) 1 hectare = 2.47 acres 2.47 football fields in 1 hectare 4.02 hectares of monarchs 4.02 X 2.47 = 9.93 football fields of monarch trees this year. Just think: Monarchs flew to Mexico from across eastern North America. They are clustered in an area smaller than 10 football fields! 1 2 3 4 5 6 7 8 9 10           Search Journey North Copyright 1997-2012 Journey North. All Rights Reserved. Questions or comments? Contact us.