🧵 Sewing & Textiles Tools

A half circle skirt needs TWICE the radius of a full circle, and cut in one piece it needs more fabric width, not less.

A one-yard square of fabric gives about 16 yards of half-inch double-fold binding. The yield grows as the square of the side.

One stitch off across a 4-inch swatch puts a 40-inch garment nearly 2 inches out. The tolerance window is one stitch wide.

Unravel the swatch and measure it. That figure knows your yarn, your tension and your cables — no chart does.

Divide by what is left, do not add the percentage back. At 20% shrinkage that mistake leaves you 3.6 inches short.

Five buttonholes have four gaps. Dividing by the count instead leaves the last hole four inches short.

Substituting by weight matches grams and nothing else. On a 1000 yard pattern, the same weight of a denser yarn leaves you 150 yards short.

The amigurumi "six per round" is 2π rounded off. Work out the rate your own gauge wants, and why a bad one never settles down.

A baby hat and an adult hat decrease at the same rate per round — the circumference cancels out. Plan the crown from your own gauge.

Dividing leaves the remainder in a lump at the end of the row — up to k−1 stitches of it. This spreads them so no two gaps differ by one.

A raglan yoke asks for four things and can only give you three. The underarm cast-on is the slack that makes the sums work.

Corner-to-corner is worked on the diagonal, so a 40×50 chart is 89 rows, not 50. Plan blocks, yarn, rows and time.

The "stop 2 inches short" toe rule is exactly a 64-stitch sock at 12 rounds an inch. On a big foot the toe is 3.2 inches.

Stripe width does not change the yarn at all. It changes the finishing by a factor of 22 — 398 ends against 18.

A stitch repeat decides which widths exist. A 24-stitch lace repeat sizes in 4.8-inch steps — twelve times coarser than a rib.

Yarn goes as area, so 10% bigger costs 21% more. Backwards, 2.5× the yarn buys only 1.58× the size.

US numbers rise with size and UK numbers fall, so a size 13 is either 9mm or 2.25mm. Exactly one number means the same needle in both.

Tracks which row of the repeat you are on as well as the total, and warns when your target length will not land on a whole repeat.

A chart shows the fabric from the right side, so on a wrong-side row a knit square is purled. Three states, one of them inverts.

A stash total cannot answer "enough for a sweater" — a garment needs one dye lot. On a real stash the total overstates by 3.8x.

The ⅞-inch rule is 0.853553 rounded up. That slack is for trimming — skip the trim and 47 units gain a full inch.

Seam orientation is worth up to a yard, and it flips on most standard sizes. One inch of quilt can cost 2.4 yards of backing.

A fat quarter and a long quarter are the same area, and which cuts more genuinely flips with the size — fat wins 9 of 16, long wins 3.

Setting blocks on point makes the quilt exactly twice the area — and the side and corner triangles are cut differently on purpose.

Scaling the cut size is wrong by the same amount per patch whatever its size — so a five-grid block scales 2.5x worse than a four-patch.

A seamless lengthwise border costs more only up to about 8 inches wide. Past the crossing it is both seamless and cheaper.

Standard quilt sizes assume a 13-inch mattress. On the deep ones now sold, 14 of 30 combinations are short — and every one is short in length.

The dark half of a log cabin takes exactly 2 x log width x rounds more fabric than the light — 18% more on a typical block.

Averaging red, green and blue misranks one fabric pair in four. Yellow has 13x the luminance of blue; averaging says twice.

Halving the line spacing exactly doubles the stitching — and the angle makes no difference at all, only the spacing does.

A "1 inch hexagon" is 2 inches across the points. And exactly three regular shapes tile the plane — there will never be a fourth.

The minimum charge means the rate is not the rate — a baby quilt pays 1.6x list and a mug rug 34x. Below it, growing the quilt is free.

One asymmetric block tiled four-up makes exactly 70 distinct quilts under rotation — counted two independent ways.

The block size comes from your smallest design, so one small shirt shrinks every block. The quilt area peaks — dropping more is not better.

Elastic cut to the measurement does nothing. And "subtract two inches" is 2.2 times stronger on a cuff than on a waist.

Sewing an eighth narrow adds two inches over eight seams. And a 2in hem on a circle skirt has 12.6in of surplus, whatever size the skirt.

Wider fabric helps in steps, not proportionally. A 22in piece fits twice across 45, 54 and 60 inch fabric, so the wide bolt buys nothing.

A shop size 10 is a pattern size 16. Choose a top by high bust, not full bust — going by full bust can be two sizes too big in the shoulders.

Sewing is usually not cheaper. Work out the break-even fabric price, and what your hours are really earning if it is.

Needle size, type, stitch length and thread by fabric. The metric needle number is literally the blade width in hundredths of a millimetre.

A nest of loops underneath is a TOP thread problem, not a bobbin one. The stitch junction always moves towards whichever thread pulls harder.

Extra fullness is often free, because widths round up. And a 36in pattern repeat can waste less fabric than a 24in one.

The burn test tells you the family, not the fibre. It cannot separate cotton from linen from rayon — they are the same material chemically.