Cast-on calculator

Enter your stitch gauge and the finished width you want. The calculator returns the number of stitches to cast on, with an optional snap to a rib multiple.

Results update as you type.

How the calculation works

The cast-on count is a width multiplied by a density. Normalise your stitch gauge to stitches per centimetre, multiply by the finished width in centimetres, then round to a whole stitch:

stitches = (stitches ÷ gauge width) × finished width

If you measured 20 stitches over 10 cm and want a 50 cm piece, that is 2 stitches per centimetre × 50 cm = 100 stitches. A gauge of 20 stitches over 4 inches (10.16 cm) normalises to 1.969 stitches per cm, so the same 50 cm piece is 98.4 stitches and rounds to 98.

Worked example: a 2×2 ribbed hat

Your swatch gives 22 stitches over 10 cm. The hat should measure 48 cm around, and the brim is worked in 2×2 rib. First find the raw count: 2.2 × 48 = 105.6 stitches. A 2×2 rib needs a multiple of four, so choose 104 (26 repeats) or 108 (27 repeats). 104 gives slightly less ease; 108 gives a softer brim. The calculator snaps to the nearest multiple, but you decide which side to land on.

What this does not account for

  • Ease. Add or subtract ease from the body measurement before entering the width. A 96 cm bust with 5 cm positive ease becomes a 101 cm finished width.
  • Pattern repeats. Lace, cables and colourwork impose their own multiples. Use the rib snap as a starting point, then adjust to the pattern multiple.
  • Edge stitches. If you will seam the piece, add the two selvedge stitches your pattern requires. The checkbox adds them for you, but patterns differ.
  • Yarn behaviour. Superwash wool, cotton and alpaca all relax differently after washing. Measure gauge after blocking.
A long wooden knitting needle holding an even row of navy cast-on loops, with a ball of yarn at the right
Every stitch begins as a loop on the needle.

Questions

Do I cast on the rounded number or the exact number?

Cast on the nearest whole stitch to the exact figure. If the result falls between two stitches, round up for a tighter, more predictable edge, or round to your pattern's stitch multiple if one is specified.

Should I use my gauge or the pattern's gauge?

Use your own measured gauge. The pattern's gauge tells you what the designer intended; your swatch tells you what your hands and yarn will actually produce.

How much ease should I add before calculating?

Ease is a design decision, not a gauge correction. Add or subtract ease from the finished measurement first, then multiply by your stitch gauge.

Why does the calculator ask for a rib multiple?

Ribbing repeats over a fixed number of stitches. A 2×2 rib needs a multiple of four; snapping the cast-on to that multiple keeps the edge continuous.

Gauge conventions follow the Craft Yarn Council's standards. The arithmetic is shown above so you can reproduce every result by hand.

Next