Lightening fast tutorial for you today. This will show you how to knit squares of the same size regardless of yarn size or tension.
This is particularly useful if you are trying to use your stash up.
You will need:
Cast on 2 stitches
1. K1, KFB
2. K1, KFB, K to end
Repeat row 2 until the side has reached the required measurement.
3. K1, K2tog, K to end
Repeat row 3 until you have 2 stitches left.
Cast off. Leave a longish tail to sew to other squares.
Using this method, you can create squares with different yarn weights that will all be the same size. The pic below shows a 5cm square in DK (pink) and a 5cm square in chunky (claret).