Tension square - rows ok but stitches off

Hi all,

I’m doing a tension square for a jumper pattern. In 1x1 rib, 8 sts x 10 rows should equal the 10cm square (using 12mm needles and super chunky yarn).

My rows measure up but the sts only equal 8.5cm.

I’m stuck as the next needle size is 15mm, which seems excessive? Please help!! Do I cast on a couple more stitches to account for this?

Thanks in advance,

Stella

What is the name and designer of your pattern?
It’s so difficult to measure stitch gauge in a rib pattern. Patterns often say, “slightly stretched” but that can mean many different things.
Are you measuring stitch gauge over the middle 10cm of the swatch? You don’t want to include the edge sts in a measurement because they are smaller. It would be better to measure over the middle 5cm and double the stitch number if you can do that.
If the stitch gauge is still off you could compensate by adding sts or even going up to the next size, depending on the pattern.