The National Convention adopted the blue-white-red Tricolor as the national flag by a Decree issued on 27 Pluviose of the Year II (15 February 1794), in the following terms: "The national flag shall be formed of the three national colours, set in three equal stripes, vertically disposed so that the blue is attached to the staff of the flag, the white in the middle, and the red flying in the air. The jack and the daily ensign shall be formed in the same way, observing the size proportions established by custom. The commissioning pennant shall also be formed of the three colours, with one-fifth blue, one-fifth white, and three-fifths red". Such design didn't survive the Congress of Viena, though; and the 'Ancien Régime' symbols were restored again until 1848.
Sources: Wikipedia(en):French ensigns | Flags of The World (FOTW) website:French Revolution (1789-1799):First Empire (May 1804-April 1814 & March-June 1815)
Sizes: large ensign W12 x L18 mm, small ensigns W8 x L12 mm, jack W6 x L9 mm, pennant W4 x L48 mm.