Fit of a garment is a personal choice. You may like your sweaters skin tight (and have the figure to pull it off), but others feel they need a bit of "wiggle room" to be comfortable.
Knit it Now Sizing charts indicate the body measurements that are used to size our garments. The individual designers add ease to various sections of the garment to obtain the style they are creating.
The pattern description should have an indication of the amount of ease in a garment. Once you have built your pattern, you can compare the measurements on the piece legend and the sizing chart to determine the exact amount of ease the designer included.
Very fitted (0 ease to negative ease)
Fitted (+1 to 1.5 inches)
Semi Fitted (2.5 to 3 inches)
Loose (4 to 5 inches)
Oversized (6 to 8 inches)