Tools
Granny Square & Blanket Layout Calculator
Enter your finished square size and the blanket you want to make. The calculator gives you the exact number of columns, rows and squares, draws a color map where two squares of the same color never touch by their sides, and tells you how many meters, grams and balls to buy for each color and for the joining border.
Free · No sign-up · Runs in your browser
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No two squares of the same color touch by their sides; colors are balanced as evenly as possible.
Shopping list per color
| Color | Squares | Meters | Grams | Balls to buy | Check colors & stock on Amazon → |
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How it works: the math behind the tool
Columns and rows: each square plus its joining border takes up (square + join) of width, so columns = round((target width + join) ÷ (square + join)), and the same for rows. The finished size shown is columns × square + (columns − 1) × join.
Color layout: squares are placed row by row; each one gets the least-used color that differs from its left and top neighbours, with random tie-breaks. With 3 or more colors this always gives a valid layout where no two same colors share a side; with 2 colors it produces a checkerboard. Shuffle draws a new balanced layout.
Columns = round((W + j) ÷ (s + j)) · Meters per square = s² ÷ 100 × 0.82 × √ρ × 1.10
Yarn: each square uses the same calibrated model as our yarn calculator, L (m) = area (cm²) ÷ 100 × 0.82 × √(m per 100 g) × 1.00 for granny clusters, plus a 10 % safety margin. The joining border is the remaining area of the blanket. Balls are rounded up per color.
Last updated: November 7, 2026
Frequently asked questions
How many granny squares do I need for a blanket?
Divide the blanket width by the size of your finished square (plus any joining border) to get the columns, and do the same with the length to get the rows. For example, 12 cm squares for a 127 × 152 cm throw give 11 × 13 = 143 squares. The calculator does this for every standard blanket size.
How do I arrange granny square colors so the same colors do not touch?
Place the squares row by row and, for each one, choose a color different from the square on its left and the one above it, preferring the color you have used least. With three or more colors this always works; the calculator draws the map for you and lets you shuffle until you like it.
How much yarn does one granny square use?
It depends on the square size and the yarn thickness. A 12 cm square in DK yarn (about 230 m per 100 g) uses roughly 20 m including a 10 % margin; select your yarn in the calculator to get the exact meters, grams and balls for each color.
What are standard blanket sizes for granny square blankets?
Common sizes are Lovey 12 × 12 in (30 × 30 cm), Stroller 30 × 36 in (76 × 91 cm), Crib 45 × 60 in (114 × 152 cm), Throw 50 × 60 in (127 × 152 cm), Twin 66 × 90 in (168 × 229 cm), Queen 88 × 92 in (224 × 234 cm) and King 104 × 92 in (264 × 234 cm).