How ThreadChart makes and estimates a chart

ThreadChart converts an image into a full-cross grid and helps you refine that result. This page describes the current method and its limits so you can decide whether a chart is suitable before buying materials.

Image and stitch dimensions

The image is sampled into the selected chart width and height. One occupied grid cell represents one full cross; an empty cell represents no stitch. The chart is not an instruction set for fractional stitches, backstitch, blended threads or machine embroidery. A source with more pixels may offer a cleaner starting point, but extra pixels do not guarantee a better composition or a more recognizable small chart.

Changing stitch dimensions changes the available detail and the possible number of crosses. Changing fabric count changes the physical size of the same grid. The maximum number of occupied positions is width multiplied by height; empty background cells reduce the actual count.

Palette selection and color approximation

The converter groups image colors, compares approximate display colors in a Lab color representation and maps the groups to entries in a limited DMC-reference palette. The selected color limit is a maximum, not a guarantee that every conversion will use that many distinct shades. Several groups can map to the same palette entry.

The bundled display palette is adapted from Sharla Gelfand's dmc reference dataset, distributed under the MIT License, copyright 2020 Sharla Gelfand. The application retains the dataset license notice. This is an independent color reference, not an official DMC measurement dataset.

Display colors come from an approximate reference dataset rather than measurements of your particular skeins under your room lighting. DMC shade identifiers do not make screen RGB values exact. Use real thread or an appropriate physical shade reference for important decisions. ThreadChart is independent of DMC.

Optional dithering distributes colors across nearby cells to suggest intermediate tones. It may preserve the impression of a gradient while increasing scattered stitches. Cleanup can replace certain isolated cells with a prevailing neighboring color; review eyes, small lettering and highlights after using it, because an isolated cell can be intentional detail.

Fabric dimensions

For Aida stitched over one square, width in inches is chart columns divided by fabric count, and height is chart rows divided by fabric count. Centimeters equal inches multiplied by 2.54. For example, 120 by 160 stitches on 16-count fabric measures 7.5 by 10 inches, or 19.05 by 25.4 centimeters. This is the design rectangle, excluding finishing allowances.

Add your own margin for framing, hoop grip, seams and edge treatment. For evenweave, use the effective stitches per inch for your chosen over-one or over-two technique. A fabric's threads-per-inch label is not automatically its stitches-per-inch value.

Thread estimates

The default estimate uses two strands and the selected fabric count. For each full cross, it models two diagonal legs on the front plus two fabric-square lengths on the back. Approximate strand-meters equal occupied crosses × (2√2 + 2) ÷ fabric count × 0.0254 × strand count × 1.2. The last factor adds an assumed 20 percent allowance.

Estimated skein equivalents divide strand-meters by 48 for an eight-meter, six-strand skein. DMC describes that product length and separable strands on its cotton floss product page. A partial skein equivalent is not a rounded shopping quantity; account for your usable stash and round purchases upward where necessary.

This is a geometric planning model, not measured consumption. Travel, starts, tails, tension, fabric thickness and confetti can change actual usage. It does not estimate specialty stitches or guarantee that the assumed allowance covers every design. Use a sample and purchasing judgment for critical projects.

Saving and printing

JSON is the editable ThreadChart project format. It is not OXS and is not advertised as interchangeable with other chart editors. PNG and SVG exports are visual outputs. The PDF includes a symbol key and tiled chart pages. Paper grid size is a readability choice; the fabric count determines the stitched dimensions. Keep the JSON project, final legend and source image together.