Sewing Machine Needles, Decoded

TL;DR:

The number tells you how thick the needle is, and the type tells you what shape its point and eye are. Match the thickness to the weight of your fabric, match the type to how your fabric is made, and change it more often than feels necessary. That's it. That's the secret to half the sewing problems people blame on their machine. For the full run-down, read on.

Skipped stitches? Puckered seams? Check the needle first.

Be honest. When did you last change your sewing machine needle? If the answer involves the words "I think it came with the machine", read on! (no judgement, we've all been there).

The needle is the cheapest part of your machine, and it does the most work. It punches through your fabric hundreds of times a minute and carries the thread down to the bobbin hook with split-second timing. When it's the wrong size, the wrong type or just plain worn out, you get skipped stitches, snagged knits, shredded thread and seams that pucker.

The good news? Most of those problems disappear the moment you put the right needle in. So let's decode the numbers on the packet, then work out which needle goes with which fabric.

80/12 looks like a maths problem, but it's not - promise!

Every machine needle packet carries two numbers separated by a slash, like 70/10, 80/12 or 90/14. They describe the same thing - the thickness of the needle - in two different systems, printed side by side so everyone around the world can find their size.

The first number is the metric size. It tells you the diameter of the needle's blade in hundredths of a millimetre, measured just above the eye. So an 80 needle is 0.80mm thick, and a 110 is 1.10mm thick. The bigger the number, the thicker the needle.

The second number is the American size. It runs on a much smaller scale (roughly 8 to 20) and doesn't convert neatly into any unit you'd recognise, so think of it as a label rather than a measurement. Thankfully it moves in the same direction: the higher the number, the thicker the needle.

The golden rule: light, fine fabrics want a fine needle and heavy, dense fabrics want a thick one. A fine needle leaves a smaller hole and won't stretch the weave of delicate fibres. A thick needle is strong enough to push through layers without bending, flexing or snapping (and sending a tiny metal needle tip flying off in to the distance).

The most common sizes you'll come across:

• 60/8 and 65/9: silk, chiffon, organza, fine lawn and voile
• 70/10: lightweight cottons, batiste, lingerie fabrics
• 75/11: lightweight knits, lycra, swimwear (usually in a stretch or ballpoint needle)
• 80/12: quilting cottons, shirting, linen blends, everyday dressmaking
• 90/14: medium-weight linen, light denim, canvas, poplin, fleece
• 100/16: heavier denim, upholstery, twill, several layers of quilting cotton
• 110/18 and 120/19: heavy canvas, thick denim seams, upholstery, leather

The size also needs to suit your thread. Thread should slide through the eye with a little room to spare, roughly filling half of the eye. Too tight and it shreds and breaks. If you're switching to a thick topstitching thread, go up a size or two (or grab a needle with a larger eye, which we'll get to).

Same size, different job

As if the numbering system isn't confusing enough, size is only half the story. Two 80/12 needles can behave completely differently, because the shape of the point, the size of the eye and the cut of the scarf (the little scoop on the back that lets the bobbin hook grab the thread) are all tuned for particular fabrics.

Woven fabrics like cotton, linen and denim are made of threads crossing over and under each other, and a sharp point slips cleanly between them. Knits are made of interlocking loops, and a sharp point can pierce those loops, snap the fibres and leave you with a ladder or a hole a week after you've finished the garment. A rounded point pushes the loops aside instead. 

Here's who's who in the needle drawer.

Universal. The all-rounder, with a very slightly rounded point that copes with most wovens and some stable knits. It's what comes in the machine and it's a fine starting place, but it's a jack of all trades. If your stitches are misbehaving, switching to a specialist needle is often the fix.

Ballpoint and Jersey. Rounded points that slide between knit loops rather than through them. Reach for these with t-shirt jersey, interlock, rib and sweatshirt fleece.

Stretch. A medium ballpoint with a specially shaped eye and scarf that stops skipped stitches on very stretchy, springy fabrics. This is your needle for swimwear, activewear, lycra, spandex and sewing on elastic.

Sharp (sometimes called Microtex). A very slim, very sharp point that pierces tightly woven fabrics cleanly. Brilliant for silk, microfibre, batiste, quilt piecing and any time you want dead-straight topstitching on a fine fabric.

Jeans (Denim). A strong, reinforced blade with a sharp point that won't deflect when it hits a flat-felled seam or the dreaded hem crossing. Use it for denim, canvas, duck and heavy twill.

Quilting. A tapered point designed to sail through multiple layers of cotton and wadding without dragging or leaving skipped stitches. Ideal for piecing and machine quilting.

Leather. A cutting point (shaped a little like a tiny blade) that slices through real leather and suede rather than punching a hole. Keep this one for genuine hides. On knits, wovens or synthetic leather it can cut fibres and weaken the seam, so a Microtex usually behaves better on faux leather and vinyl.

Embroidery. A larger eye and a special scarf that protect delicate rayon and polyester embroidery threads from fraying and breaking at speed.

Metallic. An elongated, polished eye that reduces friction on fussy metallic threads (which, let's be honest, are looking for any excuse to shred).

Topstitch. An extra-large eye and a deep groove for thick topstitching thread, or two threads through one needle. Your secret weapon for jeans-style topstitching that looks store bought.

Twin (and triple). Two or three needles on a single shank, for parallel rows of stitching on hems, pintucks and decorative work. They carry two numbers, like 4.0/80: the first is the gap between needles in millimetres and the second is the metric needle size. Use a stretch twin needle for hemming knits and your hems will flex instead of popping. (More numbers... sorry about that!)

The cheat sheet 

Treat this as a starting point, not gospel. Every machine and every fabric is a little different, so stitch a test scrap first. If it skips, puckers or snags, adjust the type before you adjust the size.

Needles don't last forever (sorry)

A needle blunts faster than you'd think. A good rule of thumb is a fresh needle every 6 to 8 hours of sewing (really!), or at the start of every new project, whichever comes first. Sewing through synthetics, batting, or anything with glue or fusible interfacing wears them down even quicker.

Your machine will also tell you when it's time, if you listen. A dull needle makes a soft popping or thudding sound as it forces its way through the fabric. You might notice skipped stitches, thread that frays or breaks, little pulls and snags in your fabric, or seams that suddenly start to pucker. And if you've hit a pin (it happens to the best of us), swap the needle straight away, even if it looks fine. A tiny burr on the point is invisible to the eye but will drag on every stitch.

When you change it, the flat side of the shank faces the back on most domestic machines. Push it all the way up before you tighten the screw, and pop the old one into sharps container or an old jar so it doesn't find it's way to the carpet, waiting for a bare foot.

So go on, check what's in your machine right now. We'll wait.