Knitting Gauge Calculator: Stitches to Cast On for Any Size

How to use gauge to size a project

Gauge is how many stitches and rows you get over a measured distance, usually 4 in or 10 cm. Divide to get stitches per inch, then multiply by the width you want. The same works for rows and length, and for crochet as well as knitting.

Stitches per inch = stitches in swatch ÷ swatch width Stitches to cast on = width you want × stitches per inch Rows to work = length you want × rows per inch New count for a pattern = pattern count × your gauge ÷ pattern gauge

Example. 18 stitches and 24 rows over 4 in is 4.5 stitches and 6 rows per inch. For a piece 20 in wide and 24 in long, cast on 4.5 × 20 = 90 stitches and work 6 × 24 = 144 rows.

If a pattern asks for 20 stitches over 4 in and you get 18, its 100-stitch cast-on would come out 22.2 in wide instead of 20. Cast on 100 × 18 ÷ 20 = 90 stitches to keep the size, then round to the pattern's stitch multiple.

Typical gauge by yarn weight

The Craft Yarn Council's guidelines over 4 in (10 cm). Your pattern's gauge always comes first.

Yarn weight	Knitting, stockinette	Needle	Crochet, single crochet	Hook
0 Lace	33–40 sts	1.5–2.25 mm	32–42 dc	1.4–2.25 mm
1 Super fine	27–32 sts	2.25–3.25 mm	21–32 sts	2.25–3.5 mm
2 Fine	23–26 sts	3.25–3.75 mm	16–20 sts	3.5–4.5 mm
3 Light	21–24 sts	3.75–4.5 mm	12–17 sts	4.5–5.5 mm
4 Medium	16–20 sts	4.5–5.5 mm	11–14 sts	5.5–6.5 mm
5 Bulky	12–15 sts	5.5–8 mm	8–11 sts	6.5–9 mm
6 Super bulky	7–11 sts	8–12.75 mm	7–9 sts	9–15 mm
7 Jumbo	6 sts or fewer	12.75 mm and up	6 sts or fewer	15 mm and up

Source: Craft Yarn Council, Standard Yarn Weight System. Checked October 2026.

Getting a gauge you can trust

Make it bigger than 4 in. A swatch about 6 in square lets you measure the middle 4 in away from the uneven edges.
Use the project's stitch pattern. Ribbing, cables and lace all give different gauges from plain stockinette.
Wash and block it the way you will treat the finished piece. Many yarns grow or shrink in the first wash.
Count half stitches. 17.5 stitches over 4 in is a different sweater from 18.

Once you know the size, the yarn calculator estimates how many skeins it takes.

Questions

How do I calculate how many stitches to cast on?

Divide the stitches in your swatch by its width to get stitches per inch, then multiply by the width you want. At 18 stitches over 4 in, that is 4.5 stitches per inch, so a 20 in wide piece takes 90 stitches.

What if my gauge doesn't match the pattern?

First try a different needle or hook size: a smaller one if you have too few stitches per 4 in, a larger one if you have too many. If you keep your gauge, multiply the pattern's stitch counts by your gauge and divide by the pattern's gauge, then round to the pattern's stitch multiple.

How big should a gauge swatch be?

At least 6 in or 15 cm square, so you can measure the middle 4 in or 10 cm away from the edges. Work it in the stitch pattern of your project and wash and block it before measuring.

Does gauge matter for crochet?

Yes, in the same way. Count stitches and rows of your crochet stitch over 4 in or 10 cm. Crochet gauge varies a lot between people, so swatching matters even more for fitted pieces.

What does a multiple of 4 plus 2 mean?

The stitch count must be some multiple of 4 with 2 more added, such as 82, 86 or 90. The calculator rounds your cast-on to the nearest count that fits, so the stitch pattern comes out even.

Knitting and Crochet Gauge Calculator