Knitting Gauge Calculator
Free knitting gauge calculator: enter your swatch gauge and desired finished size to get the exact cast-on stitches and rows to knit, with the formula shown.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Knitting Gauge Calculator Works
This calculator converts your gauge swatch into the exact cast-on stitch count and number of rows for any finished size. Enter the stitches and rows in your swatch, the swatch’s measured size, and the finished width and length you want. It scales your gauge up to the full project so the piece comes out the right dimensions.
The Formula
Gauge is simply stitches (or rows) per unit of length, which you then multiply by your target size:
Stitches per inch = gauge stitches ÷ swatch size Cast-on stitches = finished width × stitches per inch Rows per inch = gauge rows ÷ swatch size Rows to knit = finished length × rows per inch
Most patterns quote gauge over 4 in (10 cm), but this calculator accepts any swatch reference size so you can use whatever you measured.
Worked Example
Your swatch measures 20 stitches and 28 rows over 4 in, and you want a panel 40 in wide × 24 in long:
- Stitches per inch = 20 ÷ 4 = 5 sts/in
- Cast-on = 40 × 5 = 200 stitches
- Rows per inch = 28 ÷ 4 = 7 rows/in
- Rows to knit = 24 × 7 = 168 rows
Getting an Accurate Gauge
Gauge errors are the number-one cause of garments coming out the wrong size, so accuracy matters:
- Swatch big. Knit at least a 6 in square and measure the central few inches, away from the looser edges.
- Block it. Wash and block the swatch exactly as you will the finished piece — fibers can relax or grow.
- Match the stitch pattern. Stockinette, ribbing and cables all knit up at different gauges.
| Stitch gauge (per 4 in) | Stitches per inch | Cast-on for 40 in |
|---|---|---|
| 16 (bulky) | 4 | 160 |
| 20 (worsted) | 5 | 200 |
| 28 (fingering) | 7 | 280 |
Frequently asked questions
How do I calculate how many stitches to cast on?+
Divide your swatch's stitch count by its measured size to get stitches per inch, then multiply by the finished width you want. If your gauge is 20 stitches over 4 in (5 per inch) and you want a 40 in width, cast on 40 × 5 = 200 stitches.
What is knitting gauge?+
Gauge is the number of stitches and rows in a measured area of knitted fabric, usually given over 4 in (10 cm). It depends on your yarn, needle size and tension, so a gauge swatch lets you size a project accurately.
Why does my gauge matter so much?+
Even a small gauge difference compounds across hundreds of stitches. Being off by half a stitch per inch over a 40 in sweater means a 20-stitch error, enough to change the finished size by several inches. Always swatch before casting on.
How do I make an accurate gauge swatch?+
Knit a swatch at least 6 in square in your project stitch pattern, then block it the same way you will treat the finished item. Measure the central few inches, avoiding the looser edges, and count the stitches and rows in that span.
How do I find the number of rows to knit?+
Divide your swatch's row count by its size to get rows per inch, then multiply by the finished length. A row gauge of 28 rows over 4 in is 7 rows per inch, so a 24 in length needs 24 × 7 = 168 rows.