27 CFR §4.72

1. (a)Authorized standards of fill. The standards of fill for wine are the following:
2. (b)Sizes larger than 3 liters. Wine may be bottled or packed in containers of 4 liters or larger if the containers are filled and labeled in quantities of even liters (4 liters, 5 liters, 6 liters, etc.).
3. (c)Tolerances. The tolerances in fill are the same as are allowed by § 4.37 in respect to statement of net contents on labels.