Knitting Colourwork Chart Maker

Turns a photo or drawing into a knitting or crochet colourwork chart. Enter your gauge (stitches and rows per 10 cm) and each cell is drawn in the real stitch shape, wider than tall, so the finished piece is not squashed. Colours are limited to 2 to 12, and the chart carries row numbers with reading-direction arrows, stitch counts per colour and a yarn estimate. Use it for Fair Isle or intarsia motifs and crochet graphgans.

How to use

1. A chart made from the heart-and-flower sample is shown first. For your own picture, click "Drop a photo or drawing here or click to choose" or paste it with Ctrl+V.
2. Under "Technique" choose "Knitting, flat", "Knitting, in the round" or "Crochet", then enter your swatch gauge in "Stitches per 10 cm" and "Rows per 10 cm". If you do not know it, pick the nearest yarn weight under "Starting gauge by yarn weight".
3. Under "Set the size by", enter "Stitches across" or "Finished width, cm". The number of rows follows the picture and the stitch shape.
4. Set the number of yarn colours with "Most colors". For a drawing keep "Sharp edges (each cell takes its main color)" on; raise "Tidy small specks" if many lone stitches remain.
5. Tap a colour in the key to show only its cells. Use "Save as PDF", "Print" or "Save PNG"; a large chart is split into sheets at the "Printed stitch width".

How it works

• Stitch width = 100 ÷ stitches per 10 cm (mm) and row height = 100 ÷ rows per 10 cm (mm). At 20 stitches and 28 rows one stitch is 5 × 3.6 mm, and the grid cells are drawn in that ratio: a square picture 60 stitches wide becomes 84 rows.
• Each cell takes its average colour (or its main colour) and k-means in the CIELAB colour space groups the colours into as many as "Most colors" allows. With the yarn colour names chart, each group gets the nearest yarn colour name.
• Rows are numbered from the bottom. In flat knitting, odd rows (right side) read right to left and even rows (wrong side) left to right; in the round every row reads right to left. Numbers and arrows sit on the side where reading starts.
• Yarn amounts are estimates: one stitch is taken to use 2 × row height + stitch width + 1 mm of yarn (single crochet 1.5 times that), plus 10 %. The picture is processed in this browser on this device and is never uploaded.

How a picture becomes a knitting colourwork chart

The picture is divided into as many columns as stitches across, and the number of rows is the picture's height ratio multiplied by the stitch ratio (stitch width ÷ row height). Each cell takes the average colour of its pixels, or its main colour when "Sharp edges" is on. Then k-means in the CIELAB colour space groups the colours, and each group keeps its own colour or takes the nearest name from the yarn colour chart.

"Tidy small specks" merges isolated patches smaller than the chosen size into the surrounding colour, so single-stitch colour changes disappear. Every colour change in stranded knitting adds ends to weave in, so even for a photo keep dithering off and 4 to 6 colours for an easy knit.

Reading the chart flat, in the round and in crochet

In flat knitting, row 1 (the bottom row) is knitted on the right side and read right to left; row 2 is a wrong-side row, read left to right and purled. The row number sits where you start reading and the arrow shows the direction. In the round the right side always faces you, so every row reads right to left.

A crochet graphgan in single crochet alternates direction by row like flat knitting. Single crochet stitches are closer to square than knit stitches, so the starting gauge is 14 stitches and 16 rows; enter your own swatch and the cell ratio follows.

Questions and answers

Why are the chart cells not square?

A knit stitch is wider than it is tall. At 20 stitches and 28 rows per 10 cm one stitch is 5 × 3.6 mm, so a picture charted on square cells comes out squashed when knitted. This chart draws cells in the gauge ratio, so it looks like the finished piece.

What if I do not know my gauge?

Pick your yarn weight under "Starting gauge by yarn weight" for a common value. When the finished size matters, knit a 10 × 10 cm swatch with the same yarn and needles and count the stitches and rows.

How many colours should a colourwork chart have?

Fair Isle usually uses 2 colours per row and 3 to 5 in all; intarsia can take 6 to 8. When "Longest run of one color" is over 5 stitches, the floats need catching.

Can I use it for crochet?

Yes. Choose "Crochet" under "Technique": a single-crochet gauge is filled in and the reading direction alternates by row. Yarn is estimated at 1.5 times the knitting amount.

How much yarn do I need?

The key lists stitches and an estimated length in metres for each colour. It depends on yarn thickness and tension, so allow one spare ball.