The question, as stated, cannot be answered sensibly. An acre is a measure of area, with dimensions [L2]. A foot is a measure of distance, with dimensions [L]. The two measure different things and elementary dimensional analysis teaches that you cannot convert between measures with different dimensions such as these without additional information.
20.89 acres.
How many acres are 310 feet * 630 feet
48.21 acres.
About 17.2 acres.
Approximately 18.59504132231405 acres
1.18 acres = 51,400.8 sq feet.
3.09917 acres.
20.89 acres.
How many acres are 310 feet * 630 feet
108,000 square feet or 2.479 acres.
About 0.17 acres.
5.36 acres.
0.505 acres.
2.75 acres.
2.083 acres.
5.51 acres.
3.73 acres.