Practical guide 3 min read
How many granny squares do you need for a blanket?
Work out the layout for any blanket size, allow for joins and a border, and see how much yarn each round's colour really takes.
New
Tool
Granny Square Blanket Calculator
Enter the blanket size and your square size to get the layout, the finished size with joins and border, and how much yarn each colour needs. Already have a pile of squares? Switch modes and it finds the best layout for those.
Loading Granny Square Blanket Calculator…
Runs in your browser. What you enter is saved on this device only.
How to use the Granny Square Blanket Calculator
- Choose a blanket size, or enter your own width and length.
- Measure one finished, blocked square and enter its size, the join you’ll use and the border width.
- Set the rounds in each square and how many colours you’ll rotate through. If you’ve made a square already, weigh it for an exact yarn figure.
- Read the layout and the yarn for each colour. Switch to “Squares I have” to lay out squares you’ve already made.
How it’s calculated
Squares across = (blanket width − 2 × border + seam) ÷ (square + seam), rounded to the nearest whole square (or up or down, if you choose), and the same for the length. The finished size is worked back from the whole squares. Yarn per square is its area × about 0.55 yards per square inch in worsted, scaled for thinner or thicker yarn, unless you weigh a square. Round n of a granny square with r rounds covers (2n − 1) ÷ r² of its area, which is how yarn is shared between colours. Joins use 1 to 8 times the seam length, depending on the method, and the border is worked out from its area.
Questions
How many granny squares do I need for a throw blanket?
With 6 inch squares joined as you go and a 2 inch border, a 50 × 60 inch throw is 8 squares across and 9 down: 72 squares, finishing at 52 × 58 inches.
How much yarn does one granny square use?
A classic 6 inch granny square in worsted weight uses about 20 yards (18 m). For your own yarn and tension, weigh one finished square and enter its weight; the calculator uses that instead.
Do joins and borders change the size?
Yes. Each seam adds a little width: nothing for join-as-you-go, about 1/8 inch for a slip stitch seam and up to 1/2 inch for a flat braid join. Across 10 squares that’s up to 4½ inches, so the calculator adds it in. A border adds its width to all four sides.
How do I get all my squares the same size?
Block them: pin each square to its finished size on a foam mat, mist or steam it and let it dry. Squares made with one hook in the same few weeks are closest in size. Measure a blocked square before you plan the layout.
Are my numbers saved?
On this device only. Each calculator remembers what you last entered, in your browser, so you can pick up where you left off; nothing is sent to our server. Reset puts the starting values back.
Do I need an account?
No. Every craft calculator is free to use without signing in, with no limits.
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- Crochet Yarn Calculator How much yarn a blanket, scarf, hat or sweater takes, in yards, grams and skeins.
- Yarn Substitution Calculator Swap the yarn a pattern calls for and see how many skeins of yours to buy.
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- Handmade Pricing Calculator Find a selling price that covers materials, your time, fees and a profit.
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8 free craft calculators: yarn for any crochet project, granny square blankets, yarn swaps, resin, candle wax, 3D print costs and handmade pricing.
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