Something around 3,41 Km²
It will take about 35 to 40 minutes
Checkout the details here - http://www.centralparknyc.org/
If you do cycling, it will take around 35 minutes not including visiting the points of interest. I was amazed with the park which is quite big in the middle of the big apple like NYC. It's worthed to visit.
I didn't bring a tape measure with me, but I believe 50-something acres in total area.
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