Fit describes how a garment sits on the body: where it lies close, where it has room, and how it behaves when the wearer moves.
Horizontal lines run horizontal: waistline, hipline, hem. The grainline hangs vertical. Surfaces lie smooth, with no drag lines pointing at a spot that pulls. And the garment stays where it is when the wearer raises an arm or sits down. Something that sits beautifully standing still and binds at the first step does not fit.
Fit is not tightness, and it is not size. A wide coat can fit precisely and a close dress can fit badly. A size label describes a chart, not a person, which is why two garments in the same size can sit completely differently.
Three things make it: the block, which carries the body shape, the ease, which decides how much room there is to move, and the fabric, which behaves differently in every direction and can undo both. That is what a toile is for. It tests the three together, before the good fabric is cut.
Fit sits in the pattern, not in the garment. A pattern that once fitted is therefore the thing worth securing: digitally it stays exactly as it was, while paper yellows and the toile disappears into a cupboard.

Digitize sewing patterns without tracing.
Test PatternScan Pro free for 14 days with the full feature set. You need your smartphone, a printer and one pattern you always wanted digital.