Knitting Calculator
Calculate knitting cast-on stitches and rows from your swatch, then compare width at the pattern gauge.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Measure and wash/block a swatch, then enter both your measured width and the pattern’s stated gauge width. The calculator estimates cast-on stitches, rows and width at pattern gauge; it does not account for stitch repeats, shaping or yarn quantity.
Worked example
calculated with the default values below
Stitches in your swatch 20 · Rows in your swatch 28 · Swatch size 4 in · Desired width 20 in · Desired length 24 in · Pattern stitches over the stated gauge width 18 · Width used for pattern stitch gauge 4 in Your stitches per inch 5.00 · Your rows per inch 7.00 · Cast on 100 · Rows needed 168 · Your gauge versus the pattern 11.1 % · Width at the pattern gauge 22.2 in
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
CO = round(W × G_s); R = round(H × G_r); W_p = CO ÷ (P ÷ patternGaugeSize)
- CO
- Cast-on stitches
- W
- Project width (in)
- G_s
- Stitch gauge (per inch)
- R
- Rows needed
- H
- Project height (in)
- G_r
- Row gauge (per inch)
- P
- Pattern stitch count
- patternGaugeSize
- Stated pattern gauge width
Gauge rates use the stated swatch and pattern widths: stitches per inch = stitches ÷ width. Width at pattern gauge = cast-on stitches ÷ (pattern stitches ÷ stated pattern gauge width).
Frequently asked questions
How does the pattern gauge affect the width estimate?
The calculator uses the pattern stitch count and the stated width you enter to calculate pattern stitches per inch, then divides your cast-on count by that rate. This compares gauge only; shaping and stitch repeats are not included.