Every flow is different! You can wear period-absorbing underwear for as long as your flow allows. And of course, the style you wear also plays a factor, as some underwear styles are more absorbent than others. We measure our underwear for periods by absorbency, with our highest absorbency styles holding up to 5 tampons worth of flow. For some customers, they will last the whole day, and others may need to carry an extra pair of SOQO period underwear as a backup. If you feel damp or notice your flow spreading to the seams, that is an indicator you should change into a fresh pair. We suggest bringing along a resealable bag, pouch, or wet bag — so that if you do need to change out of your first pair of SOQO undies, you've got a place to put them.