Stocks from Asia and Oceania countries will be available immediately and stocks from Europe and the Americas will be available at the end of March, the agency said on Sunday, four days after the agreement was announced.
Governments have committed to make available 271.7 million barrels of oil from government stocks, 116.6 million barrels from obligated industry stocks and 23.6 million barrels from other sources, the statement said.
The bulk of the pledged reserves - 195.8 million barrels - are from member countries in the Americas, 172.2 million of that from government stocks, the IEA said.
Asia and Oceania member countries have committed to contribute 108.6 million barrels, 66.8 million of that from government stocks, and Europe has pledged 107.5 million barrels, including 32.7 million from government stocks.
The IEA statement said that 72 per cent of planned releases are in the form of crude oil and 28 per cent are oil products.
Governments of 32 countries co-ordinate their strategic oil stockpiles through the IEA, which was formed in 1974 after the oil crisis.
This is the sixth co-ordinated stockpile release since the agency's creation.
The release is aimed at combating a spike in oil prices caused by disruptions to about a fifth of global oil and gas supply along the Strait of Hormuz since the war began February 28, according to the IEA.
Iran said on Wednesday the world should be ready for oil at $US200 a barrel as its forces continue to hit merchant ships on the strait.
IEA members hold emergency stockpiles of more than 1.2 billion barrels, with another 600 million in industry stocks held under government obligation.
