Before you start: Chain · Double crochet
Filet: open spaces and filled blocks
Spaces and blocks
Every square of a filet chart is three stitches wide. A space is a double crochet followed by chain 2, skipping 2 stitches. A block is a double crochet followed by 2 more double crochets in the stitches or chain space below. Each row ends with one more double crochet, which closes the last square.
So a row of 10 squares has 31 double crochets and chains in total: 3 for each square and 1 to close.
Read the chart
Filet charts read from the bottom. Odd rows go from right to left and even rows from left to right for a right-handed crocheter, because you turn at the end of every row. Filled squares are blocks, empty squares are spaces.
Thin cotton thread and a steel hook make classic filet lace; medium cotton and a 4 mm hook make a quicker cushion or tote panel.
Draw your own
Choose Filet in the chart maker, draw your picture with blocks, and it lists every row as blocks and spaces.