Yarn Substitution Calculator
Compare your gauge to the pattern's and get adjusted cast-on stitches, row counts, and yardage — for crochet or knitting.
Standard yarn weight chart
Typical knitting gauge, stockinette stitch, for reference.
| Weight | Typical gauge |
|---|
About this yarn substitution calculator
Every knitting and crochet pattern is written around a specific gauge — how many stitches and rows fit into a set measurement, usually 4 inches or 10 centimeters. When you substitute a different yarn, or even just knit a bit tighter or looser than the designer did, your gauge shifts, and every count in the pattern (cast-on stitches, total rows, yarn needed) shifts right along with it. This calculator compares your actual swatch gauge to the pattern's stated gauge and scales the pattern's numbers to match, so a substituted yarn doesn't quietly produce the wrong size.
Enter the pattern's gauge and your own measured gauge, and the comparison updates immediately, showing how far off your stitches and rows run as a percentage. From there, fill in any of the pattern's actual numbers you want adjusted — cast-on count, total rows, or yarn yardage — and each one scales according to the measured gauge ratio. You don't need to fill in all three; leave anything blank that doesn't apply to what you're checking.
The standard yarn weight chart is included as a quick reference for typical gauge ranges across the eight standard weight categories, useful for sanity-checking whether a substitute yarn is even in the right general range before you swatch it at all.
Scaling by gauge ratio works well for straightforward stitch counts, but it's a linear approximation — complex stitch patterns, heavily shaped pieces, and anything with built-in ease may not scale perfectly this way. It's a strong starting estimate, not a substitute for swatching and checking fit as you go, especially for a garment that needs to fit a specific body.
Your entries are saved locally in your browser so they're still there next time you visit; nothing you enter is uploaded anywhere.
Frequently asked questions
Why does my substituted yarn change the pattern's numbers?
Every pattern is written around a specific gauge. A different yarn, hook, or even just your own tension can produce a different stitch and row count per inch than the designer's, which changes how many stitches and rows you actually need to reach the same finished size.
Do I need to fill in cast-on, rows, AND yardage?
No, fill in only what you need adjusted. Each of the three is calculated independently from whatever gauge numbers you've entered.
Does the "per 4 inches / per 10 cm" toggle change the math?
No, it's a label to match how you actually measured your swatch. As long as the pattern's gauge and your gauge are both stated over the same base measurement, the ratio between them is what matters, not which unit that measurement used.
Will this work for complex stitch patterns or shaped pieces?
It gives a solid straight-line estimate, but scaling by gauge ratio is linear, and complex stitch repeats or heavy shaping don't always scale perfectly that way. Treat the result as a strong starting point, then confirm with an actual swatch and fit check.
Is my gauge data saved or uploaded anywhere?
It's saved locally in your browser for convenience, so it's there next time you visit, but it's never uploaded anywhere.