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Knitting Needle Size Converter

Convert knitting needle sizes between metric (mm), US and UK, with a full reference table.

Related tools

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Knitting Cast-On CalculatorCast-on stitches and total rows for a piece from your gauge and the width and length you want.Crochet Hook Size ConverterConvert crochet hook sizes between metric (mm), US and UK, with a full reference table.Cross-Stitch Size CalculatorFinished design size from stitch count and fabric count, in inches and cm, with an optional margin.Origami Paper Size CalculatorFind the starting square size you need for a target finished origami model, from built-in model ratios or your own test fold.Beading Pattern CalculatorTotal beads and finished size for a loom or peyote pattern from rows, columns and bead size.Candle Wax CalculatorTurn a container's volume into the wax weight and fragrance oil you actually need, for soy, paraffin, coconut, beeswax, palm or a blend — in oz, grams and pounds.Cross-Stitch Floss CalculatorEstimate how many skeins of floss a design needs from stitch count, strands and fabric count.Embroidery Thread Length CalculatorEstimate embroidery thread length from stitch count, average stitch length and a waste allowance.

Knitting Needle Size Converter works straight from this page — free, instant, nothing to install. It sits under Crafts & making in our catalogue, alongside Knitting Cast-On Calculator and Crochet Hook Size Converter.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Knitting Needle Size Converter do?

Convert knitting needle sizes between metric (mm), US and UK, with a full reference table.

When would I actually use this?

Buying the right amount before starting: how many skeins a jumper needs, how much wax fills the moulds you own, how much resin a bezel takes, how much fabric a quilt binding eats.

What is the most common mistake?

Sizing from the pattern's yarn rather than your own. Two yarns sold as the same weight can differ by a fifth in metres per hundred grams, and a hook or needle size converted between systems is a nominal diameter, not a promise about gauge — knit a swatch.

How is Knitting Needle Size Converter different from Knitting Cast-On Calculator?

They sit next to each other but answer different questions: Knitting Cast-On Calculator is the one to open when you need it to cast-on stitches and total rows for a piece from your gauge and the width and length you want. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Crochet Hook Size Converter is the closest one after this: Convert crochet hook sizes between metric (mm), US and UK, with a full reference table.

What else is worth having open alongside it?

Cross-Stitch Size Calculator and Origami Paper Size Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Hook and needle equivalences follow the Craft Yarn Council's metric table; the soap calculator uses published saponification values, which vary by oil batch, so the lye figure is a starting point that a superfat margin is meant to absorb.

Further reading

All guides →
ComparisonUS 8, UK 6, 5 mm: Three Needle Scales That Never AgreeThe American numbers count up as the needle gets fatter and the British ones count down. They cross exactly once, at 4.5 mm, where both read 7 — and that single coincidence is the trap.How-toCast On From Your Gauge, Not From the PatternTwo stitches per 10 cm is the difference between a 50 cm scarf and a 55 cm one. The pattern's cast-on number is only correct for the person who wrote it.ExplainerYarn in Metres, Yarn in Grams, and the Ball Band Between ThemA pattern asks for length and a shop sells weight. 400 yards of DK is 182 g and two balls; 400 yards of fingering is 100 g and one. The bridge is a single number on the label, and reading it wrong is the reason projects run out.ExplainerThe Aida Count Sets the Size, Not the ChartThe same 100 × 120 chart finishes 23 cm wide on 11-count and 11.5 cm wide on 22-count — twice the width, four times the area, from one number on the fabric label.How-toEstimating Embroidery Thread From a Stitch CountThirty thousand stitches at 3.5 mm with fifteen per cent waste is 120.7 metres. The stitch count comes from the file; the average length is an assumption, and doubling it doubles the answer.ExplainerHow Big Will This Puppy Get? The Size Class DecidesThe same 12.7 kg puppy at sixteen weeks predicts a 21.9 kg adult if it is a small breed and 38.5 kg if it is a giant one. The arithmetic is trivial; the class you pick is worth seventy-six per cent.