Letdown doesn't happen on just one side. While your baby feeds on one breast, the other one is very often leaking at the same time — which usually means it's going into a muslin cloth, a nursing pad, or your shirt instead of anywhere useful.
Most people don't think about this as "lost" milk because there was never a plan to collect it. But over a full day of feeds, the amount that ends up in a cloth instead of a bottle adds up to more than most people expect — especially in the early weeks when supply and letdown are both strong.
A wearable milk collector doesn't do anything your body isn't already doing. It just sits on the side you're not actively feeding from and catches what would otherwise leak, so it ends up in a bottle in the fridge instead of a pile of damp cloths on the nightstand.
It's not a pump — there's no suction, nothing to switch on, nothing to assemble. You wear it, you feed, and at the end you pour out whatever collected. For a lot of people that turns out to be enough to skip a pumping session, or to start a small freezer stash without setting aside separate time for it.
Roughly how much are we talking about?
It varies a lot by person, stage, and time of day, but it's common for the non-feeding side to let down anywhere from half an ounce to two ounces during a single feed — more in the early months, less as supply regulates. Across eight feeds a day, even the low end of that range is most of a bottle, every single day, that would otherwise be soaking into a pad. It's not a number to hold yourself to; it's just context for why something with no moving parts can still add up to a meaningful amount over a week.
If leaking has just been something you deal with, our wearable milk collector is worth a look — one piece of silicone, nothing to clean but itself.
Related reading: A milk collector is not a pump. Here's the difference that matters. · Hands-free pumping without leaks: what actually helps between sessions