Answer:  ConvertIt will recognize these measurement if you replace the dash ("-") with an asterisk ("*").  For example, enter acre-feet as acre*feet. 9/16/2000 (m/d/y) Update: ConvertIt will not recognize acre-foot and acre-feet as a valid measurements.

Explanation:  ConvertIt reserves the dash for use in negative exponents, as in the measurement m*s^-2 which is equivalent to m/s^2 and meters per second squared.