The Best Thread for Filet Crochet — Sizes, Hooks, and How Big It Comes Out
Thread size decides everything in filet crochet — the hook, the gauge, and how big your chart finishes. Here's the size chart, the steel hook conversions, the threads worth buying, and how to work out finished size before you start.
Filet crochet is the one technique where the material choice is nearly the whole decision. Two stitches, one binary chart, and a thread size that silently determines whether your 100-block design finishes at eight inches or at thirty.
Thread sizes run backwards
From the Craft Yarn Council: "the smaller the number, the thicker the thread. The most common crochet threads are sizes 3, 5, 10, 20, and 30, though they are available in increments of 10 up to size 100, which is the finest."
DMC says the same on their own product page. So size 3 is chunky, size 10 is the workhorse, size 30 is fine, and size 100 is essentially spider silk. If you have ever bought size 30 expecting something substantial, this is why.
| Thread size | Typical hook | Use | | --- | --- | --- | | 3 | 2.75–3.5 mm | Bags, placemats, sturdy edgings | | 5 | ~2.0–2.5 mm | Doilies with body, table mats | | 10 | 1.5–1.75 mm | Curtains, runners, panels, bedspreads | | 20 | 1.25–1.5 mm | Detailed doilies, fine edgings | | 30 | 1.00–1.25 mm | Heirloom lace, miniature filet |
The hook ranges for 10, 20 and 30 are DMC's published figures for Cebelia; size 3 is from the Aunt Lydia's Fashion Size 3 listing. Size 5 is interpolated — treat it as an estimate.
The Craft Yarn Council puts "10-count crochet thread" in weight category 0 (Lace), with a crochet gauge of 32–42 double crochets to 4 inches on a 1.4–1.6 mm steel hook or a 2.25 mm (B-1) regular hook.
Steel hook sizes are not a reliable label
From the Craft Yarn Council's steel hook chart:
| mm | US steel | mm | US steel | | --- | --- | --- | --- | | 3.50 | 00 | 1.65 | 7 | | 2.75 | 1 | 1.60 | 6 | | 2.25 | 2 | 1.50 | 8 / 7 / 2 | | 2.00 | 4 | 1.40 | 9 / 8 | | 1.90 | 5 | 1.30 | 10 | | 1.80 | 6 | 1.15 | 10 | | 1.75 | 4/0 | 1.00 | 12 / 6 |
Look at the duplicates. US 00 is both 3.50 mm and 2.70 mm. US 10 is both 1.30 mm and 1.15 mm. US 12 is both 1.00 mm and 0.60 mm. The Craft Yarn Council's own warning is blunt: "there are variations in steel crochet hooks numbering. Regardless of the number or millimeter sizing, always complete a gauge swatch."
Buy steel hooks by millimetre. If a pattern gives only a US number, work out the mm from its stated gauge, not from a conversion chart. A steel crochet hook set (Amazon) covering roughly 0.9–2.0 mm is the sane purchase, because you will want to move a size either way after your swatch. Our crochet hook size guide has the equivalent table for regular hooks.
The three threads worth buying
Aunt Lydia's Classic Crochet Thread Size 10 — 100% mercerized cotton, 3-ply, bedspread weight. White, Ecru and Natural come in 400 yd (366 m) balls; solid colours 350 yd (320 m); multis 300 yd (274 m). Stated gauge is 32–42 dc over 4 inches on a B-1 (2.25 mm), machine washable. The default American filet thread and the one most vintage-derived charts assume — buy Aunt Lydia's size 10 (Amazon). One caution: when we checked in September 2026, the Yarnspirations listing carried a clearance/discontinued flag. Confirm your colourway is stocked before planning a bedspread around it.
DMC Cebelia — 100% cotton, combed, flame-singed and double mercerized, in 50 g balls across sizes 10, 20, 30 and 40. The nicer thread: harder finish, more sheen, better stitch edges, and DMC rates it for a 95°C machine wash and bleach, which matters for anything living on a table. DMC does not publish yardage per size; retailers list roughly 282 yd for size 10 and 416 yd for size 20 — retailer figures, not manufacturer specs.
Omega Crochet No. 10 — 100% mercerized cotton, 30 g (1 oz) balls at 174 yd (159 m), category 0 Lace, manufacturer-specified US size 6 steel hook. Saturated colours and easier to buy as a full palette. Note the smaller ball: two Omega balls are roughly one Aunt Lydia's.
Also worth knowing: Aunt Lydia's Fashion Size 3 (150 yd / 137 m in solids, 2.75–3.5 mm hook) for fast chunky filet, and Aunt Lydia's Fine Size 20 (400 yd / 366 m) for detail — no hook size is published for the 20.
Budget for blocking mats and T-pins (Amazon) too. Unblocked thread filet looks like a crumpled net; blocked filet looks like cut paper.
How big will my chart come out?
There is one honest anchor for this. Aunt Lydia's own Quilt Block Filet Pillow pattern, in Classic Size 10 on a 1.65 mm (US 7) hook, states a gauge of 12 filet blocks or mesh = 4 inches; 12 rows = 4 inches. That's exactly 3 mesh per inch. Qualifier: that pattern uses extended double crochet rather than standard dc, so it's one published data point, not a universal size-10 filet gauge — no manufacturer publishes one of those.
Taking 3 mesh per inch as the anchor and scaling by hook diameter, here is what a 10-block-wide section of chart measures:
| Thread / yarn | Hook | Mesh per inch | 10 blocks wide | | --- | --- | --- | --- | | Size 10 thread | 1.65 mm | 3.0 (verified) | 3.3″ | | Size 20 thread | 1.25 mm | ~3.9 (estimated) | ~2.6″ | | Size 3 thread | 3.0 mm | ~1.7 (estimated) | ~6.1″ | | Worsted yarn | 5.0 mm | ~1.0 (estimated) | ~10″ |
Only the first row is a published figure. The other three are ours, scaled linearly from hook diameter — an approximation, and your tension moves it more than the arithmetic does. The worsted row lands on the familiar "one block per inch" rule of thumb, which is a sanity check, not a proof.
Instead of trusting any table, ours included: crochet a 10 × 10 block swatch in your actual thread on your actual hook, block it, measure, and divide 10 by the measured width. Multiplied into your chart's block count, that is your finished size.
The filet crochet pattern maker shows finished dimensions as you change the block count, so you can drive the design from the size you need rather than discovering it at the end. Generate the chart from a photo in the converter or draw it cell by cell in the designer.
When worsted yarn filet works
Thread filet is a multi-month object. Worsted filet is a weekend.
Worsted-weight filet works for blankets, throws, cot covers and wall panels — the graphic block-and-mesh look at furniture scale, where the lace needn't be delicate. A 5 mm hook gives roughly one block to the inch, so a 50-block chart is a 50-inch blanket and the planning arithmetic is trivial.
Use a firm, tightly-plied worsted. Bernat Super Value and Knit Picks Brava Worsted hold the mesh open; a soft haloed acrylic lets the open squares close up and the picture disappears. The blanket yarn guide covers the trade-offs, and how to substitute yarn gets you from a thread pattern to a yarn one — noting that jumping two or three weight categories changes finished size threefold or more.
Yardage for a curtain or a runner
No manufacturer publishes a yards-per-square-inch figure for filet, so here is our method and our number, labelled as an estimate. The Aunt Lydia's pillow above uses 2 balls of Classic Size 10 for an 18″ × 18″ cover. Reading that as a two-face cover — 648 in² of fabric — gives roughly 1.1 yards of size 10 thread per square inch. A planning figure, not a spec.
| Project | Size | Area | Thread (est.) | Balls to buy (350 yd) | | --- | --- | --- | --- | --- | | Table runner | 14″ × 40″ | 560 in² | ~620 yd | 3 | | Café curtain | 24″ × 30″ | 720 in² | ~790 yd | 4 | | Full window panel | 36″ × 60″ | 2,160 in² | ~2,380 yd | 8 |
Buy one more ball than the table says, in one dye lot — a dye lot change shows badly in flat lace, and running out at 90% is how large filet pieces get abandoned. Run your dimensions through the yarn calculator; how much yarn do I need has the general method.
The small kit that matters
- A magnetic chart keeper (Amazon). Filet charts are dense grids of near-identical squares, and losing your row costs an hour of unpicking.
- Locking stitch markers every ten blocks along the foundation. Miscounting the foundation chain by two is the classic filet disaster.
- A Clover Amour 5.0 mm hook (Amazon) for the worsted-weight version.
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