100 gaj is exactly 100 square yards, because both units are the same size.
That is 900 square feet or 83.61 square meters.
In traditional south Asian land units that is 3.31 marla.
For context, this is roughly the size of a typical urban residential plot.
Next stepGaj is used widely in India and Pakistan for residential plot sizes. For legal documentation, always confirm the local definition in use as regional variants exist.