Filet crochet chain calculator

Charted crochet needs the right starting chain for its technique, and a chart only looks right if each square comes out square. This calculator turns a chart's size into the starting chain and row 1 stitch count for filet (4-dc or 3-dc blocks), overlay mosaic or tapestry crochet, works out the finished size, and checks the shape of each square at your gauge.

How to use the calculator

1. Choose filet with 4-dc blocks (ch-2 spaces), filet with 3-dc blocks (ch-1 spaces), overlay mosaic or tapestry.
2. Enter the chart's squares across and down.
3. For filet, choose whether row 1 starts with a solid block or an open mesh.
4. Enter your stitch and row gauge.

How the calculator works

• 4-dc filet: each block is 3 stitches plus a closing dc it shares with the next block, so row 1 = 3 × squares + 1. Chain 2 more for a solid start (dc in the 4th chain from the hook), or 4 more for an open start (dc in the 8th chain).
• 3-dc filet: row 1 = 2 × squares + 1. Chain 2 more for a solid start (4th chain), or 3 more for an open start (dc in the 6th chain).
• Overlay mosaic: one sc per chart square plus an edge sc at each side, so row = squares + 2, plus 1 chain.
• Tapestry: one sc per square, plus 1 chain.

For an open start, the skipped chains make the first dc and the top of the first space: in 3-dc filet, 3 chains for the dc, 1 for the space and 1 skipped chain, so you work into the 6th chain and no chain is left over at the end of the row.

Finished width = row 1 stitches ÷ stitch gauge; height = chart rows ÷ row gauge

Square shape = square width ÷ square height. More than 10% off and the picture will look squashed or stretched; the calculator warns you.

Reading your results

• Chains to make and stitches in row 1.
• Finished size: width × height.
• Square shape: 1.00 is perfectly square.
• Start: the chain and the first stitch of row 1, written out.

Worked examples

• 4-dc filet, solid start: a 40 × 50 square rose chart. Row 1 is 3 × 40 + 1 = 121 stitches; chain 123. At 6 stitches and 2 rows per inch each mesh is 0.5 in square, and the piece is about 20.2 × 25 in.
• 4-dc filet, open start: the same chart needs 121 + 4 = 125 chains, with the first dc in the 8th chain from the hook.
• 3-dc filet, open start: a 30-square-wide chart has 2 × 30 + 1 = 61 stitches in row 1; chain 64 and work the first dc in the 6th chain from the hook.

Accuracy and limits

• The chain counts are exact and covered by our automated tests, including a check that an open start leaves no spare chain at the end of row 1.
• One chart row is one crochet row. Charts that pair two rows per square need their own allowance.
• In mosaic, the first and last stitches are edge stitches outside the chart.

Common mistakes

1. Using a stitch chart's chain count for filet. Filet blocks share their closing stitches, so the count is not simply 3 or 4 per square.
2. Ignoring the square shape. Double crochet rows are often shorter than a mesh is wide; the picture then looks squashed.
3. Starting row 1 in the wrong chain. Solid starts work into the 4th chain; open starts into the 6th (3-dc) or 8th (4-dc).

Tips for more accurate results

• If the squares come out wider than tall, try extended double crochet or a taller stitch for the posts, or a smaller hook.
• Mark every 10th square of the chart and every 10th block of your row with stitch markers.
• For corner-to-corner pictures, plan with the C2C crochet calculator instead.

Frequently asked questions