Standard Yarn Weight Chart & WPI Conversion Calculator

The complete guide to comparing yarn systems — convert Wraps Per Inch (WPI) to US weights, UK Ply, and recommended needle sizes.

Interactive Yarn Weight Converter

Select by name or enter your WPI to get full needle & gauge data instantly.

Convert by Name
Find by WPI
-- Choose a Weight --
    Category US Weight WPI Range Gauge (4") Recommended Needle UK Term Aus/NZ
    Lace030-40+33-40 stsUS 000-1 (1.5-2.25 mm)Lace2 Ply
    Super Fine114-3027-32 stsUS 1-3 (2.25-3.25 mm)4 Ply4 Ply
    Fine212-1823-26 stsUS 3-6 (3.25-4.0 mm)DK5 Ply
    Light311-1521-24 stsUS 6-8 (4.0-5.0 mm)DK8 Ply
    Medium49-1216-20 stsUS 8-10 (5.0-6.0 mm)Aran10 Ply
    Bulky56-912-15 stsUS 10-13 (6.0-9.0 mm)Chunky12 Ply
    Super Bulky65-67-11 stsUS 13-19 (9.0-16.0 mm)Super Chunky14 Ply

    How to Measure WPI (Wraps Per Inch)

    Don't have a label? Measuring Wraps Per Inch is the most accurate way to identify yarn weight at home.

    1. Find a tool: Grab a pencil, ruler, or dedicated WPI gauge.
    2. Wrap the yarn: Wind side-by-side — touching but not overlapping.
    3. Check tension: Natural tension — not too tight, not too loose.
    4. Mark one inch: Use a ruler to mark exactly 1 inch (2.54 cm).
    5. Count & enter: Count full wraps inside that inch, then enter into the calculator.

    Example: 14 wraps per inch = Worsted (Medium) weight.

    Note: Fiber content (cotton vs. wool) and material flexibility can slightly affect WPI tension. Always knit a gauge swatch to confirm.

    Understanding Ply (UK, Australia, NZ)

    Patterns from UK, Australia, or NZ use "Ply" as a weight category (not a literal strand count).

    • 4 Ply ≈ US Fingering / Super Fine
    • 8 Ply ≈ US DK / Light (most common in AU)
    • 10 Ply ≈ US Worsted / Aran (Medium)
    • 12 Ply ≈ US Bulky / Chunky

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    Why Yarn Weight Labels Can Be Misleading

    "Worsted" on the ball band is a starting point, not a guarantee. Different manufacturers, fibres, and even dye lots can cause the same labelled weight to knit up at wildly different gauges. A slippery silk-blend "DK" may have a WPI of 15 — technically Light — while a dense cotton DK might only measure 11. The WPI system cuts through the label ambiguity by measuring the yarn itself: wrap, count, and you know exactly what you're working with.

    Fibre content also affects how a yarn sits in the hand. Wool's elasticity allows a slightly looser wrap with natural bounce-back, while cotton and linen are inelastic and tend to wrap tighter for the same physical thickness. This is why our WPI calculator includes the disclaimer about fibre flexibility — and why a gauge swatch remains the gold standard for any project where sizing matters.