since they sell name brand manufacturers/fabrics, i would think the widths would be somewhere between 42"-44". i order from them a lot and have gotten a lot of stonehenge or bali/hoffman batiks end of bolt pieces. today even if a fabric should measure a good 45" wof, it is not 45" of usable fabric due to the manufacturer's marking in the selvage. the selvages can take up at least 2" of fabric if not more.
i think the standard usable today is around 42".