Yarn Weight, Ply & Metreage: The Hidden Maths Behind Your Knitting
When I first came back to knitting, I thought I understood yarn weight. I mean — 8 ply is 8 ply, right? Easy.
But then I started swapping yarns in patterns and suddenly, nothing fit quite right. A “chunky” yarn that looked perfect turned a fitted cardigan into a tent. Another time, my scarf came out half the size it was meant to be — and I couldn’t work out why.
The secret culprit? Metreage.
Weight (or ply) tells part of the story. But the number of metres per ball tells you the rest — and it’s what really determines how much fabric you’ll get from your yarn.
Let’s break it down.
1. Yarn Weight (or Ply): The Thickness
Yarn weight (in NZ and the UK, usually called ply) is the most common way to describe how thick the yarn is.
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2–4 ply = fine yarns for lace or baby garments
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8 ply (DK) = the versatile middle ground
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10–12 ply = chunky, quick-to-knit yarns
Each “weight” has its own typical tension or gauge, which tells you how many stitches and rows per 10 cm you’ll get.
👉 But here’s the catch: two yarns both labelled “8 ply” can behave very differently if their metreage doesn’t match.
2. Metreage: The Real Indicator of Size and Drape
Metreage (or yardage) is the number of metres of yarn in each ball or skein.
Think of it as the true measure of thickness and density.
Let’s say you have:
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Yarn A: 100g ball, 200m
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Yarn B: 100g ball, 280m
Both might say “8 ply,” but Yarn A is heavier and denser — you’ll get less fabric from it. Yarn B is finer and will knit up lighter and drapier.
If you substitute Yarn B into a pattern written for Yarn A, your finished garment could end up too small or with a looser texture.
💡 Pro tip: Always compare metres per 50g or 100g — that’s your real apples-to-apples number.
3. Why Weight Alone Can Mislead You
A ball of yarn might weigh the same, but fibres have different densities:
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Wool is light and springy.
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Cotton is dense and heavier.
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Alpaca and possum are airy and soft, so they go further metre for metre.
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Mohair adds loft and lightness — a ball may look small but covers surprising ground.
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Merino sits in its own category — superfine, soft, and elastic, it offers warmth without weight.
That’s why two yarns that both say “100g” can produce wildly different results — because the type of fibre changes how much length you get per gram.
4. How to Match a Substitute Yarn (Without Guesswork)
If you can’t get the exact yarn in your pattern, here’s what to look at:
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Check the metreage per 50g or 100g ball.
Aim for something within about 5–10% of the original pattern yarn. -
Compare fibre types.
Swapping wool for cotton or alpaca will change drape, warmth, and elasticity. -
Swatch, swatch, swatch.
Knit a small square and measure your gauge — it’s the easiest way to see if your substitute will work. -
Ask us!
Seriously, bring the pattern in (or email it) — we’ll help you find the best match from what we stock.
5. When Yardage Becomes Your Superpower
Once you start paying attention to metreage, you’ll spot patterns.
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Lightweight yarns = more metres per ball, drapier fabric.
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Dense yarns = fewer metres per ball, thicker fabric.
You’ll also find it easier to estimate how much yarn you’ll need — and avoid the dreaded “I ran out one ball short” moment.
6. Real-World Examples: How Metreage Changes Everything
Here’s a look at a few 8 ply (DK-weight) yarns from our range — all technically “the same weight,” but with very different metreage, fibre types, and results.
| Yarn Example | Fibre Type | Ball Size | Metreage | What That Means |
|---|---|---|---|---|
| Cleckheaton Country 8 Ply Wool | 100% Wool | 50 g | 95 m | Classic bounce and structure — great for garments that hold shape. |
| Sesia Jeans Cotton | 100% Egyptian Cotton | 50 g | 120 m | Finer, heavier drape — perfect for summer tops or baby knits. |
| Countrywide Merino Possum 8 Ply | 70% Merino / 30% Possum | 50 g | 130 m | Airy and warm; goes further metre-for-metre than wool, super-soft finish. |
| Heirloom Easy Care Acrylic 8 Ply | 100% Acrylic | 100 g | 200 m | Even texture, machine washable, affordable — ideal for everyday blankets. |
| Rowan Kid Classic (Merino/Mohair/Polyamide Blend) | 70% Wool / 22% Mohair / 8% Nylon | 50 g | 140 m | Light halo and subtle sheen from mohair — lovely for soft jumpers. |
💡 Notice how the metreage climbs as fibres get lighter or smoother? That’s why checking those numbers matters — it tells you exactly how far your yarn will go.
👉 You can browse our full 8 ply range and see metreage listed on product pages.
7. The Bottom Line: Don’t Just Look at the Label
Once you start noticing those little numbers on the label — the metres per ball — a whole new world opens up. You’ll understand why some yarns feel lighter, drape better, or last longer, even when they’re the same ply. It’s not just about the weight; it’s about what that weight does.
When you compare metreage, you’re not guessing anymore — you’re choosing yarns like a pro. You’ll save yourself frustration, wasted money, and a few “why is this sweater enormous?” moments along the way.
So next time you’re eyeing up a new project, flip the label, find that metreage, and give yourself a quiet pat on the back. You officially know more than most knitters do when they start.
👉 Need help comparing yarns or substituting for a pattern? Pop in and see us at The Wool Shop, or message us online — we’re always happy to help you find the perfect match.
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