Crochet Hook Size Chart, Yarn Weight Chart and How Much Yarn You Need
Find crochet hook sizes in mm, US and UK, the standard yarn weights with the hooks and gauge that suit them, how many yards a hat, scarf or blanket takes, and how to wash what you made, all in the Crochet Bobble Reference tab.
Hook sizes, yarn weights and yardage are the numbers you check over and over. They all live in the Reference tab, next to the stitch dictionary, and they follow the Craft Yarn Council standards.
Crochet hook size chart
Open Reference and tap Hook Sizes.
Each hook is listed by its size in millimeters, with its US letter and number and its old UK number beside it. For example, 5.5 mm is a US I-9.
Go by the millimeters. A hook's letter is the brand's label, not a measurement: a G hook is 4 mm from one brand and 4.25 mm from another. The UK numbers are for vintage patterns, since UK hooks have been sold in millimeters for decades.
Scroll down for Steel hooks, which use their own numbering and go with crochet thread and lace weight yarn.
Yarn weight chart
Tap Yarn to see everything about yarn.
- Yarn shows the yarn weights, yarn types, tips on choosing yarn, and how much yarn you need.
- Washing what you made — care by fiber →
- Reading a yarn label — what the symbols mean →
- What weight is this yarn? — wraps per inch →
- The topic list narrows the page to Weights, Yarn types, Choosing yarn or How much yarn.
Tap any yarn weight to open it. Each one shows what it's used for, its hook range in millimeters, the matching US and UK hooks, and the usual gauge over 4 inches.
The weights run from 0 (lace) to 7 (jumbo). Medium (4) is the most common, and the easiest to learn on.
How much yarn do I need?
Pick How much yarn from the topic list for a chart of about how many yards it takes to make a hat, scarf, socks, shawl, adult sweater, baby blanket or afghan, in each yarn weight.
On a phone, slide the chart sideways to see the heavier weights. These are starting points: your gauge, the stitch pattern and the yarn all change the real number.
Tip: for a pattern you're actually making, the pattern's own yardage is the better guide. The gauge tracker can tell you how much more or less you'll need at your gauge.
What weight is this yarn? Wraps per inch
For a ball with no label, open What weight is this yarn? Wrap the yarn snugly around a pencil, count how many wraps fit in one inch, and type the number into Your count.
The app tells you which weights match. Some counts fit two weights, because the standard ranges overlap. Wraps per inch narrows it down, and a gauge swatch settles it.
How to wash what you made
Open Washing what you made for care by fiber: acrylic, cotton, wool, superwash wool and more. Each one says how to wash it, how to dry it, and what to watch out for.
A blend follows its fussiest fiber, so a wool blend gets wool care. Making it as a gift? Open the WIP's Details on the WIPs tab and tap Print gift care tags (PDF)… to print tags with the same care instructions.
Read the symbols on a yarn label
Open Reading a yarn label to learn the little pictures on a ball band. The rule that covers most of them: a cross through a symbol means don't, and dots mean heat, so more dots mean more heat.
Frequently asked questions
What does "worsted" mean? It's a common name for medium (4) yarn. Search "worsted" in the Reference and it finds medium (4).
Why do my hook's letter and millimeters not match the chart? Letters vary by brand. Always go by the millimeters stamped on the hook.
Are these charts on the website too? Yes. See the crochet hook size chart and the yarn weight chart.
Ready to try it? Crochet Bobble opens right in your browser, on a phone or a computer.
Open Crochet Bobble