Crochet Thread Guide: Sizes, Steel Hooks and First Projects
Crochet thread is numbered backwards — size 30 is finer than size 3. Learn the sizes, which steel hook goes with each, and easy first thread projects.
Pattern at a glance
US terms- Skill level
- All levels
- Time
- 5 minute read
In this post
Crochet thread is fine, tightly twisted (usually mercerised cotton) yarn used for doilies, lace, edgings, jewellery and tiny details. It has its own numbering system that runs backwards: the higher the number, the finer the thread.
The rest of this post is just below — free, as always.
Thread sizes and hooks
| Thread size | Thickness | Usual hook | Used for |
|---|---|---|---|
| Size 3 | Thickest; close to fingering yarn | 2.25–2.75 mm | Bags, tops, mandalas, first thread projects |
| Size 5 | Fine | 1.75–2.1 mm | Doilies, edgings, garments |
| Size 10 | The standard | 1.5–1.75 mm | Doilies, snowflakes, lace, filet |
| Size 20 | Very fine | 1.25–1.5 mm | Fine lace, edgings |
| Size 30 and up | Finest | 1.0–1.25 mm or smaller | Heirloom lace, tatting-style work |
Hooks under about 2.25 mm are usually steel, with their own numbering (also backwards). Buy by millimetres to avoid confusion.
Tips for working with thread
- Start with size 3 or size 10 — size 10 is the most common in patterns.
- Good light and a contrasting background (dark cloth under white thread).
- Hold the hook loosely — steel hooks are thin and tempt you to grip.
- Add a grip to steel hooks for comfort on long sessions.
- Block everything: thread lace transforms when pinned and stiffened.
Easy first thread projects
- Snowflakes: three rounds in size 10 — snowflake pattern.
- Flat hearts: the magic-ring heart becomes a tiny charm — heart pattern.
- Bookmarks: a narrow strip with a picot edge — bookmark pattern.
- Earrings: mini acorns or flowers.
- Filet panels: see filet crochet.
Common questions
What size crochet thread is best for beginners?
Size 3 is the easiest to see; size 10 is the most common in patterns. Start with size 3 if size 10 feels too fine.
Can I use thread for amigurumi?
Yes, for micro amigurumi — tiny toys an inch or so tall. Use size 10 thread and a 1–1.5 mm hook.
Is crochet thread the same as embroidery floss?
No. Crochet thread is a single, tightly twisted strand; embroidery floss is six loose strands meant to be separated.
Have you tried thread crochet yet? It's addictive. 🧵
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