Stitch gauge from swatch calculator

Zero or negative stitch counts, row counts, or measured sizes are rejected with a clear invalid_input error, because a non-positive count or length cannot define fabric density.

What swatch gauge means and how to measure it

This calculator never invents units; it only divides stitches_count by measured_width and rows_count by measured_length, so if you measured in inches your stitch_gauge is stitches per inch, and if you measured in centimetres it is stitches per centimetre.

How to call the API and what comes back

Every field must be strictly positive; values at or below one times ten to the minus fifteen are treated as non-positive and rejected, which covers the required zero and negative measurement errors as well as empty counts. Send a JSON body with four required finite positive numbers: stitches_count (aliases stitches, stitch_count, sts, sts_count, stitch_number), measured_width (aliases width, swatch_width, w, width_measured), rows_count (aliases rows, row_count, rws, row_number), and measured_length (aliases length, swatch_length, height, l, length_measured). Absolute values must stay within the published limit of one trillion so intermediate quotients remain finite in IEEE double precision on the Worker and in the browser. On success the response echoes rounded inputs, sets stitch_gauge and stitches_per_unit to the same rounded density, sets row_gauge and rows_per_unit to the same row density, adds stitches_per_4, rows_per_4, stitches_per_10, and rows_per_10 as scaled reports for common pattern quote windows, formula to a compact summary of the equations, message to a short English summary, and steps to an ordered array of substitution lines. Failed validation—missing fields, non-finite numbers, values outside absolute limits, or non-positive counts or measurements—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.

Practical tips, units, and how this differs from cast-on tools

Measure gauge after the same wash and block you plan for the finished fabric; wet gauge and dry gauge often differ, and this tool will faithfully scale whatever counts and lengths you feed it. Prefer a full four-inch or ten-centimetre window rather than two stitches across half an inch when you can, because small counting or ruler errors amplify when you divide and later multiply by a wide sweater front. Prefer sending numbers rather than pre-formatted strings when you control the client; string numbers are accepted only when they match a strict finite numeric pattern. When teaching, pair examples: twenty-two stitches over four inches and thirty rows over four inches yields five point five stitches and seven point five rows per unit; twenty-two stitches over ten centimetres and thirty rows over ten centimetres yields two point two stitches and three rows per centimetre; and measured_width zero demonstrates the hard invalid_input path on non-positive measurement. This landing targets people searching for a stitch gauge from swatch calculator, stitches and rows per inch from a sample, or how to calculate knitting gauge from measurements; it is not a cast-on planner, not a yarn-yardage estimator, and not a needle-size recommender. Prefer this capability when you have just finished measuring a physical swatch and need density first; once you know stitch_gauge and row_gauge, feed them with target width and length into a cast-on gauge calculator such as hobby.knitting_gauge to plan stitches to cast on and rows to knit. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately set measured_width to zero. Round-trip checks are easy: recompute stitches_count divided by measured_width by hand and confirm it equals stitch_gauge within the same twelve-decimal rounding, and confirm that stitch_gauge times four equals stitches_per_4.