How many granny squares do I need for a blanket?

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.

How much yarn does each granny square use?

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.

How do I join granny squares?

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.

Do I need extra yarn for joining and borders?

Yes. Joining uses approximately 1-2 metres per seam edge. A border can use 50-150m depending on width and blanket size. This calculator includes an estimate for joining yarn.

What size granny squares should I use?

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.

KnitCalcs

Granny Square Calculator — Squares & Yarn for Blankets

Calculate how many granny squares you need and total yarn required for a blanket or garment.

Blanket Width

Finished blanket width

Blanket Length

Finished blanket length

Square Size

Finished size of each square

Yarn Per Square

Metres of yarn per square

Ball Meterage

Metres per ball of yarn

Price Per Ball (optional)

How We Calculate This

This calculator divides your blanket dimensions by square size to find the grid layout, then multiplies by yarn per square.

The formula

Squares wide = Blanket width / Square size (rounded up)

Total squares = Squares wide x Squares long

Total yarn = (Squares x Yarn per square) + Joining yarn

Frequently Asked Questions

Related Calculators

Crochet Gauge Calculator

Calculate crochet gauge from swatch measurements for any stitch type.

Amigurumi Calculator

Calculate increase and decrease rounds for amigurumi spheres and shapes.

Circle Calculator

Calculate increases per round for flat crochet circles of any size.

Oval Calculator

Calculate foundation chain and increases for flat crochet ovals.

Crochet Blanket Calculator

Calculate yarn, chain count, and rows for crochet blankets.

Last updated: February 2026

All calculations are estimates based on standard yarn weights and gauge. Results may vary with individual tension, yarn brand, and needle size.