They still refer to quarter acre plots here, even though NZ is now metric. These plots seem to be between 840 and 1100m2. Where I live these are not a standard size, they're all over the place, so I have no idea what corresponds to an acre, if any of them do!
Using the lower figure, a full acre would be 3640 m2.
A meter is about 39 inches, is 39/36 yds. So an acre would be 1.08 * 3640 or about 3950 square yards.