Too many undies

How many pairs of underwear does a person really need? As I was putting away some clean clothes just now I realised that my drawer was getting rather full. I've been in a decluttering place for a few days, so I pulled out the drawer and had a look. Ridiculous. So, I started culling. Some knickers I've had a bit too long. Some I will never be able to wear again due to baby-induced body changes. So, I tossed them. Although I'm normally quite happy to donate my second-hand clothes to the local op shop, I do NOT pass on my underwear, so they went into the rubbish.

How many pairs is too many?