Head to head
Steel vs Aluminum Crochet Hooks
Two materials, two numbering systems that run in opposite directions, and one very easy mistake to make.
By Sawyer V. · Published September 27, 2026
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The short answer
Steel hooks are for crochet thread and aluminum hooks are for yarn, and they are not points on one scale - they use separate numbering systems that run in opposite directions. Steel sizes get smaller as the number gets bigger, so a steel No. 10 is 0.75mm while an aluminum size 10 is nothing of the sort. Buy steel only if you are working thread; buy aluminum for anything you would call yarn.
Why steel exists at all
Crochet thread is far finer than yarn, and the hooks that work it have to be correspondingly fine. Below about 2mm, aluminum starts to flex and bend under the tension thread crochet uses. Steel does not, which is the whole reason for the material.
So steel is not a premium version of aluminum. It is the material you move to when the hook gets so thin that aluminum stops being rigid enough.
The comparison
| Steel | Aluminum | |
|---|---|---|
| Intended for | Crochet thread | Yarn |
| Typical range | Sub-2mm | 2.25mm to 10mm and beyond |
| Numbering | Higher number, smaller hook | Letters, and bigger is bigger |
| Rigidity at fine sizes | Holds its shape | Flexes and can bend |
| Head | Usually in-line | In-line, tapered or rounded |
| Typical projects | Doilies, edgings, tablecloths, filet | Everything else |
The mistake nearly everyone makes once
Buying a steel set to crochet yarn with. The handles on some steel sets look identical to the yarn-weight sets from the same brand, and the number on the package looks reassuringly familiar.
Worsted yarn on a sub-2mm steel hook is close to impossible - the yarn is several times too thick for the head, and forcing it produces a fabric like wire. If you have bought a steel set by mistake it is not wasted; it is simply waiting for you to try thread crochet. Best steel crochet hooks covers the range properly.
What thread crochet is actually like
- Slower, by a lot. A doily is a project measured in evenings rather than hours.
- Worked at high tension, which is hard on the hands - a gripped steel hook is worth more here than at yarn sizes.
- Unforgiving of uneven stitches, because there is no loft to hide them.
- Transformed by blocking. A finished doily looks like a crumpled mess until it is pinned out and dried.
- Cheap to try. A single steel hook and one ball of size 10 thread is a very small outlay.
Sizes, and the overlap in the middle
The two ranges are not quite adjacent - they overlap slightly around 1.75mm to 2.25mm, which is the only place you will ever have a genuine choice of material for the same size.
| Range | Material | Typically used for |
|---|---|---|
| 0.75mm to 1.65mm | Steel only | Fine thread, size 20 and 30 |
| 1.75mm to 2.25mm | Steel or aluminum | Size 10 thread, or very fine yarn |
| 2.25mm to 6.5mm | Aluminum | Fingering through worsted yarn |
| 6.5mm to 10mm | Aluminum | Bulky and chunky yarn |
| Above 10mm | Plastic or resin | Super bulky and jumbo |
In that overlapping band, pick on what you are working rather than on the hook: thread wants the steel hook's finer head even at the same nominal diameter, and a fine yarn wants the aluminum one. Above 10mm the material changes again for a different reason - weight rather than rigidity - which best jumbo crochet hooks covers.
Which to buy
- Crocheting yarn of any weight: aluminum. This is almost everyone, almost always.
- Doilies, edgings, filet or thread lace: steel, in the size the pattern names.
- Not sure which your pattern means: check the millimeters, not the number.
- Buying one steel hook to try: get a gripped one. Thread tension is hard on fingers and a bare 1mm shaft is unpleasant.
- Amigurumi in thread: steel, and expect it to take a long time.
Crochet thread sizes explained covers the thread side, and best crochet thread the materials.
One of each
Susan Bates Steelite Steel Crochet Hook Set
Nickel-plated steel in the in-line Susan Bates geometry, intended for lace, doilies, tablecloths and edgings.
$7.95 - View on Amazon#ad disclosure - price as of September 27, 2026
Clover Amour Steel Crochet Hook Set
Steel hooks with the Amour elastomer grip, in the sub-2mm range - No. 10 is 0.75mm.
$35.00 - View on Amazon$39.0010% off · #ad disclosure - price as of September 27, 2026
Susan Bates Silvalume Aluminum Crochet Hooks
The aluminum comparison: anodized aluminum, in-line head, B-1/2.25mm to N-15/10mm.
$8.75 - View on Amazon$9.286% off · #ad disclosure - price as of September 27, 2026
Aunt Lydia's Classic Crochet Thread Size 10
What steel hooks are actually for: size 10 mercerized cotton thread, 3-ply, 350-400yd depending on color.
$9.99 - View on Amazon#ad disclosure - price as of September 27, 2026
Questions people actually ask
What is the difference between steel and aluminum crochet hooks?
Steel hooks are made for crochet thread and are mostly sub-2mm; aluminum hooks are made for yarn and start around 2.25mm. Steel stays rigid at sizes where aluminum would flex, which is the reason the material changes.
Why are steel crochet hooks numbered backwards?
It is a separate historical scale in which a higher number means a smaller hook - Clover's steel No. 10 is 0.75mm. Aluminum hooks use letters where bigger means bigger. Buy on the millimeter figure and the confusion goes away.
Can you use a steel hook with yarn?
Not practically. Worsted yarn on a sub-2mm hook is several times too thick for the head, and forcing it makes a fabric like wire. Steel hooks are waiting for thread, not for yarn.
Do I need a steel hook for lace?
For thread lace, yes. For lace-weight yarn, no - that is still aluminum territory. The material follows the thickness of what you are working, not the word lace.
Are steel hooks harder on your hands?
The work is, rather than the hook. Thread crochet is done at high tension for long stretches, which is why a gripped steel hook is worth more than a gripped aluminum one.