How do I read a knitting gauge?

I’m starting a new project and i’m trying to be good and determing my stitches per inch before I start knitting.

So, I bought this Boye knitting gauge with holes to determine your needle size, some measurement marks that make no sense to me in the middle, and a sliding part at the bottom that says “stitches per inch.”

No instructions included. How do I use this thing to measure sts per inch in garter stitch.

See if these links help.

Forget the sliding sts per inch thing, and just use a ruler. You would want to knit about 6 to 10 more stitches than the pattern says for 4", and measure 4" worth of stitches in the middle of a row. Do that in several places to make sure it’s consistent. Don’t include edge stitches because they curl under and aren’t the same size as the ones in the center.

So if the gauge for the pattern is 19 sts per 4", CO about 24 sts, knit for about 3" then measure your piece. Count how many sts are in a 4" measurement across the row. The reason gauges are given as per 4" is because it’s really hard to measure a partial stitch which you would get at 4.75 sts per in the example of 19 sts I gave. Even 9½ sts per 2" would be hard to get accurate.

Is this what you have?

Lay your swatch flat, position the gauge so that 0 (zero) is at the left outside of the first stitch you are counting and move the slider over 10 stitches. The pointy part at the top will point the the number of stitches per inch.

Mine came with instructions, which of course I’ve misplaced and can’t quote verbatim, but that’s how it works. HTH

ETA: I had to find mine before I could answer your question. I don’t really use it if I need an accurate count rather than close-enough and had to look at it before I was sure I remembered how to use it.