The typical bottle of wine or champagne contains 750ml of fluid.
Common bottle sizes of champagne are measured as multiples of the standard bottle.
Magnum 2 * 750ml
Jeroboam 4 * 750ml
Rehoboam 6 * 750ml
Methusalah 8 * 750ml
Salmanazaar 12 * 750ml
Balthazaar 16 * 750ml
Nebuchadnezzar 20 * 750ml