Granny Square Calculator
One weighed square tells you everything: how many squares the blanket takes, how much yarn it all needs, and how many skeins to buy.
How the granny square calculator works
- Lay out the grid. Columns = target width ÷ square edge, rounded up; rows do the same for height. A 127 x 152 cm blanket from 15 cm squares is 9 columns x 11 rows = 99 squares.
- Weigh the yarn. Total grams = squares x grams per square: 99 x 12 g = 1,188 g, covering a 135 x 165 cm finished blanket.
- Convert to skeins. Skeins = total grams ÷ grams per skein, rounded up. At 100 g per skein, 1,188 g means buying 12 skeins.
Granny square FAQ
How do I find yarn per granny square?
Crochet one full square, then weigh it on a kitchen scale accurate to the gram. That single number beats any estimate, because it captures your exact yarn, hook, and number of rounds.
How do I know how many squares I need?
Divide the target blanket width by one square's edge length and round up — same for height. For a 127 x 152 cm blanket from 15 cm squares: 9 columns x 11 rows = 99 squares.
How much joining yarn should I add?
Joining and edging typically add 10 to 20 percent of the square yarn, depending on the joining method. Whip stitch through back loops is frugal; a border of several rounds is not.
Why does the total use more squares than my target count?
The layout needs whole squares, so both dimensions round up. If your stated count is below what the layout needs, the calculator uses the layout number so you are not caught short mid-join.