Many land parcels aren't perfect rectangles. If you have four side measurements and one diagonal, this works out the real area.
Label the plot corners A, B, C, D going around the boundary. Enter the four side lengths, plus the diagonal distance from corner A to corner C (splitting the plot into two triangles).
This uses the standard surveying method of splitting the plot into two triangles along the diagonal and applying Heron's formula to each. For plots with more than 4 corners, or where you don't have a diagonal measurement, consult a licensed surveyor for an accurate reading.
Many land parcels in India, especially agricultural plots, aren't neat rectangles — they follow old field boundaries, natural features or historical survey divisions. Measuring just length × width in these cases can significantly overstate or understate the real area.
The 4-sides-plus-diagonal method used here is a well-established manual surveying technique, but it assumes the plot is a simple quadrilateral (no concave corners). For plots with more than four corners, or where precision matters for a legal transaction, get a proper survey done by a licensed surveyor.