Knitting Gauge Calculator

Choose the reference swatch size (4 in, or 10 cm, which the tool treats as 3.937 in). Enter the pattern's gauge line, then the stitches and rows you actually counted over the same size on your washed swatch. Enter the finished width and length in inches, and optionally any stitch count from the pattern you want converted.

With the pattern at 20 stitches and 28 rows and your swatch at 22 and 30, the calculator reports the pattern at 5.00 st/in and 7 rows per inch, and you at 5.50 st/in and 7.50 rows/in. For a 20 in width: 20 × 5.5 = 110 stitches to cast on. For 24 in of length: 24 × 7.5 = 180 rows.

The gauge ratio is 5.5 ÷ 5 = 1.100, so a 100-stitch instruction becomes 110 stitches. It matches the cast-on because 100 stitches at the pattern's 5 st/in was always meant to measure 20 in. When the two numbers disagree in your own project, the pattern count was designed for a different width than the one you typed.

Gauge per inch: pattern st/in = pattern stitches ÷ swatch size; pattern rows/in = pattern rows ÷ swatch size; your st/in and rows/in are worked the same way from your swatch.

Cast-on: stitches = round(target width × your st/in).

Rows: rows = round(target length × your rows/in).

Gauge ratio: your st/in ÷ pattern st/in. Adjusted pattern count = round(pattern stitch count × gauge ratio).

All three counts are rounded to whole stitches or rows. Note that the ratio uses stitch gauge only, so the adjusted count is for widths, not row-based instructions such as "work 40 rows"; convert those yourself with your rows per inch.

A sweater pattern lists a gauge of 18 stitches and 24 rows over 4 in and tells you to cast on 180 stitches for a 40 in finished chest, knitting 15 in to the underarm.

Your swatch, straight off the needles, measures 19 stitches and 26 rows. Entered as-is, the calculator says cast on 190 stitches and knit 98 rows.

After washing and drying flat, the same swatch relaxes to 17 stitches and 23 rows. Now your gauge is 4.25 st/in and 5.75 rows/in, the ratio is 0.944, and the calculator says cast on 170 stitches and knit 86 rows. The pattern's 180 converts to the same 170.

The difference is not academic. Cast on the 190 stitches from the unwashed swatch and, once the sweater is washed, the chest measures about 44.7 in. Follow the pattern's 180 without converting and it measures about 42.4 in. Only the washed-swatch number gives the 40 in you wanted.

Knit it big enough. Aim for a swatch at least 6 in square, in the stitch pattern the garment uses, so you can measure 4 in in the middle away from curling edges.

Treat it like the finished piece. Wash it the way you will wash the garment, press out the water, and dry it flat without stretching. Wool, alpaca and superwash yarns often grow when wet; some cottons and acrylics barely change.

Count, do not stretch. Lay a ruler on the flat swatch and count stitches across 4 in in two or three places, and rows down 4 in. Include half stitches. If you knit the garment in the round, swatch in the round, since many knitters' tension differs between flat and circular work.

Sanity-check against the yarn. The Craft Yarn Council's Standard Yarn Weight System lists worsted-weight (category 4) yarn at 16-20 stitches over 4 in in stockinette. A worsted swatch at 26 stitches means a counting error or very tight knitting.

Gauge matters most where fit is the point: sweaters, cardigans, fitted hats, socks and mittens. Errors compound across the width. Take 200 stitches written for 5 st/in, which should measure 40 in. Knit at 4.5 st/in they measure about 44.4 in; at 5.5 st/in, about 36.4 in. Half a stitch per inch moves the result by roughly 4 in either way.

Scarves, shawls, dishcloths and most blankets forgive a gauge miss, because a slightly wider scarf is still a scarf. The catch is yarn: looser knitting makes a larger piece from the same stitch count, and a larger piece uses more yarn, so a gauge you ignore for fit can still leave you a skein short.

The calculator does flat, rectangular gauge arithmetic. It does not model shaping such as waist decreases, raglan lines or sleeve tapers, and it does not know about ease, so enter the finished measurement you want rather than a body measurement. Cables, lace and ribbing each have their own gauge and pull in or spread differently from stockinette, so swatch the actual stitch. Row-gauge conversions of pattern instructions are left to you.

Once you know your gauge, the Yarn Yardage Estimator turns the same stitch and row counts into yards of yarn to buy. Crocheters planning a throw can use the Crochet Blanket Dimensions Calculator, which does the equivalent sizing from crochet gauge. If you are pairing a knitted piece with a sewn lining or garment, the Sewing Fabric Yardage Calculator converts pattern yardage for your fabric width and nap.