Do the math
before you cast on.
Knitting and crochet gauge, yarn and sizing calculators.
Gauge, yardage and needle sizes are the three places a project goes wrong. These tools turn your swatch into a number you can actually follow — no account, no app.
- 39
- yarns indexed
- 8
- standard weights
- 0
- sign-ups
01 — Tools
Four questions, answered with arithmetic.
No sign-up, no app. Each tool prints its formula so you can check the result by hand.
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01
Gauge → stitches
Cast-on calculator
Turn your gauge swatch and a finished width into the exact number of stitches to cast on.
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02
Metres → skeins
Yarn substitution calculator
Convert metres and skeins when the original yarn is discontinued, unavailable, or simply not in your stash.
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03
mm ↔ US ↔ UK
Needle & hook converter
Metric, US and UK sizes in one table — plus the steel hook sizes that run backwards.
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04
Gauge → category
Yarn weight finder
Work out which of the eight standard weights your yarn is, from gauge or wraps per inch.
02 — Reference
Needle sizes, without the guesswork.
US numbers are not standardised across manufacturers. Millimetres are. Use this table when a pattern gives you a number you don't recognise.
| Metric | US | UK |
|---|---|---|
| 2.25 mm | 1 | 13 |
| 2.75 mm | 2 | 12 |
| 3.25 mm | 3 | 10 |
| 3.75 mm | 5 | 9 |
| 4 mm | 6 | 8 |
| 4.5 mm | 7 | 7 |
| 5 mm | 8 | 6 |
| 5.5 mm | 9 | 5 |
| 6 mm | 10 | 4 |
| 6.5 mm | 10.5 | 3 |
| 8 mm | 11 | 0 |
| 9 mm | 13 | 00 |
03 — Library
Specs you can compare, not marketing copy.
Put-up, fibre, gauge and recommended tools for yarns people actually buy. Every record shows when it was last checked.
| Yarn | Weight | Put-up | Gauge | Needle |
|---|---|---|---|---|
| Lion Brand Wool-Ease | 4 · Worsted | 85 g · 180 m (197 yd) | 18 sts × 24 rows / 10 cm | 5 mm |
| Cascade Yarns 220 | 4 · Worsted | 100 g · 200 m (219 yd) | 18–20 sts / 10 cm | 4.5 mm / 5 mm |
| Stylecraft Special DK | 3 · DK | 100 g · 294 m (322 yd) | 22 sts / 10 cm | 4 mm |
| DROPS Lima | 3 · DK | 50 g · 100 m (109 yd) | 21 sts × 28 rows / 10 cm | 4 mm / 5 mm |
| Malabrigo Rios | 4 · Worsted | 100 g · 192 m (210 yd) | 18–22 sts / 10 cm | 4 mm / 5 mm |
| Bernat Blanket | 6 · Super Bulky | 300 g · 201 m (220 yd) | 8 sts × 13 rows / 10 cm | 8 mm |
04 — Guides
The reasoning behind the numbers.
51 guides, from measuring a swatch to buying the last skein.
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01
How to measure gauge properly
A swatch is only useful if you measure it the way you will wear it. Here is the sequence that produces a number worth calculating with.
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02
Why your gauge is off (and what to change)
Needle size is only one variable. Tension, fibre, stitch pattern and blocking all move the number — here is how to tell which one moved yours.
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03
How to measure row gauge (and when it matters)
Row gauge decides whether a raglan, sleeve cap or colourwork repeat fits. How to measure it, when it matters, and when to ignore it.
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04
Gauge in the round vs flat
Knitting in the round removes the purl rows, and that can change your gauge. How to swatch for circular knitting and what to do if the numbers differ.
Good fabric starts before the first stitch.
The calculators assume a swatch you trust, a yarn you can identify, and a quantity that accounts for swatching, seaming and dye lots. These guides cover the parts arithmetic cannot see.
- How to measure gauge5 min
- How to substitute yarn7 min
- How much yarn do I need?6 min
Method
Sizes follow the Craft Yarn Council's industry standards. Yarn specifications are recorded as facts — put-up, fibre content, gauge — and cross-checked against manufacturer and retailer listings.