An import quota is a limit on the quantity of a good that can be produced abroad and sold domestically. It is a type of protectionist trade restriction that sets a physical limit on the quantity of a good that can be imported into a country in a given period of time. If a quota is put on a good, less of it is imported. Quotas, like other trade restrictions, are used to benefit the producers of a good in a domestic economy at the expense of all consumers of the good in that economy.

The primary goal of import quotas is to reduce imports and increase domestic production of a good, service, or activity, thus "protect" domestic production by restricting foreign competition. As the quantity of importing the good is restricted, the price of the imported good increases, thus encourages consumers to purchase more domestic products. In general, a quota is simply a legal quantity restriction placed on a good imported that is imposed by the domestic government.

Because the import quota prevents domestic consumers from buying a imported good, the supply of the good is no longer perfectly elastic at the world price. Instead, as long as the price of the good is above the world price, the license holders import as much as they are permitted, and the total supply of the good equals the domestic supply plus the quota amount. The price of the good adjusts to balance supply (domestic plus imported) and demand. The quota causes the price of the good to rise above the world price. The domestic quantity demanded falls and the domestic quantity supplied rises. Thus, the import quota reduces the imports.