Begin with the fabric you want to make
A cast-on estimate connects three things: your measured stitch gauge, your desired finished width, and any stitch-count rule in the pattern. Measure a swatch made with your intended yarn, needles, and stitch pattern. Prepare it as you intend to care for the finished piece, then measure it after it has settled.
The width input is the intended width of the fabric. It is not automatically a body measurement, and it does not calculate ease, shaping, or a garment size. For a fitted item, follow the pattern’s construction and sizing guidance before deciding which width to use.
Example 1: a width without a repeat constraint
Suppose your swatch has 20 stitches across exactly 10 cm and you want fabric 30 cm wide. The raw estimate is 30 × 20 ÷ 10 = 60 stitches. With a repeat size of one and no extra stitches, the stitch calculator returns 60.
This estimate assumes the measured gauge applies across the finished width. A tight cast-on, a border in another stitch, or a change in tension can affect the result. Use the number as a planning aid and check the actual fabric as you work.
Example 2: a multiple of eight plus two
Now keep that 30 cm target and 20-stitch gauge, but use a pattern that requires a multiple of eight stitches plus two extra stitches. Valid counts follow 8 × repeats + 2. The nearby choices are seven repeats plus two = 58 stitches, or eight repeats plus two = 66 stitches.
At the same gauge, 58 stitches estimate to 58 ÷ 20 × 10 = 29 cm. The 66-stitch option estimates to 33 cm. The calculator chooses the nearest valid count, so it returns 58 in this example. Whether a slightly narrower piece is appropriate depends on the project; the closest number is not necessarily the right design choice.
Enter the extra stitches only once. If the instruction says “multiple of eight plus two,” the two stitches are outside the repeats. Do not also add the same two stitches to the width calculation or cast them on again after using the result.
Example 3: working in inches
In inch mode, measure your gauge across exactly four inches. A gauge of 20 stitches over four inches and a target width of 12 inches gives 12 × 20 ÷ 4 = 60 stitches before repeat constraints.
Four inches is 10.16 cm, so a count measured across 10 cm is not exactly the same measurement as a count across four inches. Choose one mode and measure over its stated span. Changing the selector does not convert the numbers already in the fields.
Know what this calculation leaves out
- Row gauge and the number of rows needed for length.
- Increases, decreases, shaping, and construction-specific cast-ons.
- Different gauges in borders and the main stitch pattern.
- Yarn quantity or whether a finished item will fit.
The calculator allows at least one full repeat. If that minimum produces a width far above your target, reconsider the repeat, yarn, or project size. For a closer look at measuring, read the gauge guide. For a first practice piece, try the garter-stitch square guide.