PIECE IT TOGETHER

Granny square blanket calculator

Plan your grid, preview the colors and count the squares before you start.

.form-panel,.plan-actions{display:none}This is an example plan. Enable JavaScript to enter your own measurements. The calculation method below is readable without JavaScript.

Measurement units

Example measurements are filled in. Replace them with your own.

01Build your grid

Squares across

Squares down

Finished square side cmMeasure a complete blocked square.

Width added by each join cmUse 0 for a join that adds no width.

Border width on each edge cmUsed for dimensions only. Enter border yarn below.

02Estimate your materials

Yarn per complete square gWeigh a representative square, including all its colors.

Yarn for all joins and border gYour measured or pattern-based estimate. Not calculated from border width.

Weight per ball g

Yarn already owned g

Extra planning allowance %

03Play with colorPreview paletteA visual arrangement. It does not calculate yarn per color.

How to plan a granny square blanket

Choose whole numbers of squares across and down. The calculator multiplies them for the motif count, adds the space introduced by internal joins, then adds a border on both sides of each dimension. The grid shows an illustrative three-color layout.

Width = columns × square side + (columns − 1) × join width + 2 × border width

A 63-square example

Seven squares across by nine down makes 63 squares. With a 15 cm finished square, a 0.3 cm added join and a 5 cm border, the blanket measures 116.8 × 147.4 cm. At 12 g per square, the motifs use an estimated 756 g. Add your own 120 g finishing estimate and 10% extra to plan for 963.6 g overall.

Why enter joining and border yarn separately?

Dimensions do not determine stitch consumption. A narrow dense border may use a different amount from a wider open border. Enter a measured or pattern-based estimate for all finishing yarn. Setting a border width changes dimensions only.

How many balls of each color do I need?

The displayed yarn total combines all colors. The palette does not calculate per-color material use. Measure yarn used in each color of a sample square and estimate joins and border colors separately before buying.

Is this a written pattern?

No. It is a dimensions, materials and layout aid. Follow a suitable pattern for each square, the joins and the border. For the complete worked method, read granny square blanket math.

Method maintained by Loop & Yard. Published 2026-10-30. Examples illustrate the formulas; they are not measurements of a tested finished blanket.