What is the capacity of period underwear?

You can wear period underwear for as long as your flow allows. AllMatters period underwear holds the equivalent of 1–2 tampons (10 ml) for light/moderate models and 3–4 tampons (15-20 ml) for moderate/heavy models.

Some prefer to use them as their primary period care, while others use them as a backup to a cup, disc, or tampon. They are also great for overnight use, spotting, or discharge.

It can be tricky at first to know how long you can wear them, but you will quickly get a sense of your flow and how long you can stay leak-free. You’ll know the underwear is full if you see blood reaching the seams of the gusset or if the fabric begins to feel damp. While we recommend changing into a fresh pair every 8–12 hours, the underwear themselves are designed to last for years.