Granny Square Calculator — Squares & Yarn for Blankets

Divide the blanket width and length by the square size. A 120x150cm throw with 15cm squares needs 8x10 = 80 squares. Always make a few extras in case any turn out uneven.

A standard 15cm (6-inch) 4-round granny square in DK yarn uses approximately 10-12 metres. Larger squares or more rounds use proportionally more. The best way to find out is to crochet one square and measure the yarn used.

Popular methods include slip stitch join, dc join, whip stitch, mattress stitch, and join-as-you-go. Slip stitch creates a flat seam. DC join creates a raised ridge. Join-as-you-go attaches squares during the last round, saving seaming time.

Yes. A slip-stitch or whip-stitch join uses roughly 2-3 times the seam length in yarn, so a single 15cm (6-inch) square edge needs about 0.3-0.5 metres. A border can use 50-150m depending on width and blanket size. This calculator includes an estimate for joining yarn.

Common sizes are 10cm (4in), 15cm (6in), and 20cm (8in). Smaller squares create a more intricate look but require more joining. Larger squares are faster to make and join but offer less design flexibility. 15cm is the most popular size.