#negative ease

Ease has to do with the difference between the size of the garment and the size of the person wearing it. Positive ease means the garment is larger (so it’s baggy), while negative ease means the person is larger (so it stretches to fit). 

'negative ease' is just the technical term for 'making it a bit small so it will cling'. anything that stretches to stay in place when it's on your bod has negative ease.

for example, the average adult head is 22-24 inches around. most hat patterns are 20 inches around. the hat is smaller than your head, which would be a problem if it was, say, a ball cap, but since it’s knit, it stretches, and that makes it stay on.

'positive ease', as you can guess, is when you make something larger than the body it’s supposed to fit. a jacket has positive ease, because you want to be able to slip it on and off easily and have room for other clothes underneath it. a skirt has negative ease at the waist so it’ll stay on, and then (unless it’s a clingy mini or pencil skirt i guess) flares out to have positive ease so you can move your legs freely.

i reckon this question comes in response to the one about the thigh-high stockings? the thing about negative ease is, it works best as a proportion rather than a flat number. so short socks, say up to around boot-sock height, only need about an inch of negative ease, but when you get up to thicker parts of the leg you might want an inch and a half or two inches, or even three if you’re a superhero with mighty thighs.

A quote from the book Socktopus by Alice Yu that I want to keep for future reference:

A well-fitting sock is usually 1 inch (2.5 cm) narrow and shorter than actual foot measurements, but you can adjust this to your preference.