The amount of fluid your ladies' incontinence underwear holds usually depends on the brand and design. However, most women's incontinence briefs should be able to hold anywhere from 16 and 40 ounces of liquid. This information is sometimes available in the product description or on the brand website. Keep in mind the human bladder can hold roughly 19 ounces of fluid, so your incontinence panties should be able to keep you covered regardless of any accidents.