Louisiana Civil Code Tit. VII, Art. 2494. Sale of immovable for lump price

When the sale of an immovable has been made with indication of the extent of the premises, but for a lump price, the expression of the measure does not give the seller the right to a proportionate increase of the price, nor does it give the buyer the right to a proportionate diminution of the price, unless there is a surplus, or a shortage, of more than one twentieth of the extent specified in the act of sale.

When the surplus is such as to give the seller the right to an increase of the price the buyer has the option either to pay that increase or to recede from the contract.