Help with cable and gauge

If I wanted to add a cable detail to a pattern that wasn’t written with a cable, how would I determine how this would affect my gauge, if at all? I am curious about adding some cable to a pattern for a hooded pullover in particular.

The best way to tell is to work 2 gauge swatches, one without the cable and one with. The cable will pull the knit fabric in. Are you thinking of a single cable or an overall cable pattern?

Although one cable on the front of a sweater may not have a major effect on the width, it’ll certainly affect the “local” width, say of a shoulder. (I found this out when I placed a cable one side of a sweater and over the shoulder. )