Knitting cast-on calculator

How to use this calculator

1. Enter the span and stitch count from a representative swatch.
2. Enter the target width in the same unit. Use a repeat of 1 and 0 edge stitches if there is no pattern constraint.
3. Enter the repeat size and total extra stitches across both edges, not the count for only one edge.

How many stitches should I cast on for my width?

Multiply the target width by your measured stitches per unit, then find totals that fit the stitch repeat plus all fixed edge stitches. The closest total may be narrower or wider than the target; compare the predicted widths before choosing.

Once the width is chosen, work out the row count for your target length. Rows to length →

The calculation

Ideal count = width × stitches per cm. Valid counts = repeat × positive whole number + total extra edges. We show adjacent valid counts and their predicted widths; ties choose the lower count.

A worked example

50 cm at 20 stitches per 10 cm suggests 100 stitches. With a 6-stitch repeat plus 2 edge stitches, choose 98 (49 cm) or 104 (52 cm).

Before you cast on

Edges mean the total extras across both sides. At least one full repeat is required; if your target is smaller than that minimum, both choices are the minimum and can exceed the target. Check the pattern’s cast-on and border conventions.

Measure a representative, washed and dried swatch without stretching it. See method sources and measurement guidance.

Display values round to 2 decimals; calculations keep full precision. Counts are whole numbers. No calculator can promise fabric behaviour.