While I’ve done a tension gauge in a project done before - I’ve realized that I should perhaps create a post JUST on this topic to make it easier to find in the future.
I covered this in: 2023 May 14 - Cat Hammock
As I am reviewing a YouTube Video (at the 9 minute mark) I thought I’d include the directions noted there as the post above were from my machine manual.
A tension gauge tells us how many rows and stitches to create fabric within a 10cm square.
Arrange 35 needles on both sides of 0 and cast on (70 needles). Cast on. Now set the row counter to zero. Work 20 rows at your desired settings. Exchange yarn to contrast yarn and knit two rows. Cut contrast and switch back to prior yarn. Knit 30 rows with the main yarn. Take 21st needle on both sides of center and push both into D position. Place a piece of contrast yarn into each hook for marking and push both needles back into the B position by hand. At this point knit another 30 rows with the main yarn then work two rows with the contrast yarn. Then 20 more rows with the main yarn. Now remove the yarn and remove the carriage across to remove the swatch from the machine. Since the tube was stretched from side to side on the machine roll it into a tube f rom side to side then pull it lengthwise. Press as yarn dictates. Use the GREEN rules with STITCHES noted with S ruler. Example shown was 30 stitches. To measure ROW use the R ruler. Measure between contrast rows. The ruler says 41 rows. Note stitch dial and tension mast gauge.