Shenandoah Valley
Fiber Festival
Tools for makers

Yarn substitution calculator

Standing at a booth with a pattern in one hand and a skein you love in the other? Work out how many skeins you actually need — and whether the swap is a sensible one — before you get to the register.

Knitting & crochet Works offline once loaded

What does your pattern call for?

Copy these numbers from the pattern and from the ball band of the yarn it was written for.

Craft
How does the pattern give the amount?
Use the number for the size you are making.
From the original yarn's ball band.
Lets us compare thickness properly, not just category.
Stitches across 10cm / 4in, in stockinette or as the pattern states.
Everything is calculated in your browser. Nothing is sent anywhere.

The yarn you want to use instead

All of this is on the ball band. If you are at the festival, the vendor can tell you anything the band leaves out.

Stitches across 10cm / 4in, from the ball band.
Covers swatching, your own tension, and small changes to the pattern. 10% suits most projects; go to 15–20% for colourwork or if you may lengthen sleeves.

Your result

Quantity is arithmetic and reliable. Compatibility is a warning system — the swatch is the final word.

Skeins to buy
Before you cast on: knit or crochet a generous swatch — at least 15cm square — wash it exactly as you plan to wash the finished piece, dry it flat, and only then measure. Alpaca, superwash and silk blends in particular can grow considerably once wet. A swatch costs one evening; a sweater that does not fit costs a season.
How it works

Three checks, one practical answer

01

Match the length, not the skeins

Patterns are really asking for a total length of yarn. Two yarns that both say “100g” can differ by hundreds of metres, so we convert your requirement into length and then back into whole skeins — always rounding up.

02

Compare the labels

Length per 100g is the single most useful number on a ball band. Together with the weight category and the label gauge it tells you whether two yarns are genuinely similar or just filed under the same name.

03

Then swatch anyway

Fibre content, ply construction and your own tension all change the fabric. A washed, dried swatch is the only test that counts — treat everything above as a way of avoiding obvious mistakes, not a guarantee.


Reference

Yarn weight categories

The Craft Yarn Council standard, with the names you will actually hear used at a festival. Gauge figures are worked over 10cm (4in) on the recommended needle or hook.

CategoryAlso calledKnit gaugeNeedle Crochet gaugeHookTypical yd / 100gWPI
0 — LaceCobweb, thread, 2-ply33–40 sts1.5–2.25mm32–42 dc1.6–1.4mm steel600–1,000+18+
1 — Super FineFingering, sock, 4-ply, baby27–32 sts2.25–3.25mm21–32 sc2.25–3.5mm380–48014–18
2 — FineSport, baby23–26 sts3.25–3.75mm16–20 sc3.5–4.5mm300–38012–14
3 — LightDK, light worsted, 8-ply21–24 sts3.75–4.5mm12–17 sc4.5–5.5mm230–30011–13
4 — MediumWorsted, aran, afghan, 10-ply16–20 sts4.5–5.5mm11–14 sc5.5–6.5mm160–2309–11
5 — BulkyChunky, craft, rug, 12-ply12–15 sts5.5–8mm8–11 sc6.5–9mm110–1606–8
6 — Super BulkySuper chunky, roving7–11 sts8–12.75mm7–9 sc9–15mm50–1105–6
7 — JumboGiant, arm-knitting6 sts or fewer12.75mm+6 sc or fewer15mm+under 50under 5

Yardage figures are typical ranges rather than rules — a lofty woollen-spun yarn and a dense worsted-spun yarn can sit in the same category and still differ by 20%. WPI (wraps per inch) is a handy check with no ball band: wrap the yarn snugly around a ruler for one inch, without stretching or overlapping, and count.


Shopping the substitute at the festival

More than 100 vendors bring hand-dyed yarn, farm yarn and millspun to Berryville every September. Bring your pattern and the numbers from this page — dyers know their own bases better than any calculator, and most will happily wind a swatch length so you can try before you commit to a sweater quantity.

Browse the vendor list

Questions

Substitution FAQ

Is matching the weight category enough?

No. The categories are deliberately broad — category 4 covers everything from a light worsted at 230 yd/100g to a dense aran at 160. Two yarns in the same category can produce noticeably different fabric. Compare length per 100g as well, and check the gauge on the band.

Why does the calculator round up and add a margin?

You cannot buy two thirds of a skein, so quantity always rounds up to whole skeins. The margin covers swatching, the fact that your tension is not the designer's, and the very common decision to add length to a body or sleeve. It also protects you against dye lots — a hand-dyed yarn you go back for in January may not match the one you bought in September.

Can I substitute a different fibre?

Sometimes, but expect a different garment. Cotton has almost no memory and will grow where wool springs back; alpaca and silk drape and can lengthen dramatically under their own weight; superwash wool behaves differently from untreated wool of the same thickness. Cables and textured stitches also lose definition in slippery or hairy fibres. Treat a fibre change as a design decision, not a like-for-like swap.

What if my pattern only gives a total yardage?

That is the easier case — switch the requirement toggle to “Total length” and enter it directly. You will not get a length-per-100g comparison unless you also enter the original yarn's weight per skein, but the quantity maths works fine without it.

Does this work for crochet?

Yes. The quantity arithmetic is identical. Bear in mind that crochet generally consumes noticeably more yarn than knitting for the same area, so if you are converting a knitting pattern to crochet, set the margin higher — 20% is a reasonable starting point, and more for dense stitch patterns.

Where do the reference figures come from?

The gauge, needle and hook ranges follow the Craft Yarn Council's Standard Yarn Weight System, which is the same system most published patterns and ball bands use. The yardage and WPI columns are typical ranges observed across commercial and hand-dyed yarns rather than part of the formal standard, so treat them as orientation.