Useful values

Common UK fabric widths: quilting cotton 110 cm, dress cottons 115 cm, lining 140 cm, dressmaking 150 cm, upholstery 137–155 cm.

Typical shrinkage by fibre: cotton 3–5%, denim and linen 4–8%, wool 5–8%, silk 2–4%, polyester usually under 2%. If you're not pre-washing, use the higher end.

Standard seam allowances: 1.5 cm (5/8″) on commercial patterns, 1 cm (3/8″) on many indie patterns, 6 mm (1/4″) for quilting. A 10% allowance on the calculator above covers seams plus normal cutting waste.

Common sewing measurements

• 1/4″ = 6 mm (quilting seam allowance)
• 3/8″ = 1 cm (Burda and many indie patterns)
• 1/2″ = 1.3 cm
• 5/8″ = 1.5 cm (standard commercial pattern seam allowance)
• 1″ = 2.54 cm exactly
• 36″ = 91.4 cm (1 yard)
• 45″ = 114 cm (typical cotton width)
• 60″ = 152 cm (typical dressmaking width)

About bias binding

Bias means 45° to the selvedge — the diagonal of the fabric. Cut on the bias, woven fabric stretches, which is why bias binding follows curves smoothly while straight-grain binding bunches.

The square method (above) is one of the most efficient ways to make continuous bias. You mark parallel lines, sew the fabric into a tube offset by one line, then cut along the spiral — yielding one long, unbroken strip.

Single-fold binding is cut at 2× the finished width and folded once on each long edge. Double-fold is cut at 4× and folded twice — sturdier and the most common choice for everyday garments.

About garment fabric estimates

Pattern envelopes are always more accurate than any estimator because they're based on the actual marker layout — the Tetris-style nesting of all the differently-shaped pattern pieces. Use this estimator when you're shopping before you've picked a pattern.

Fabric width effect: moving from 150 cm wide to 112 cm wide typically adds 25–35% more length needed, because pieces can no longer sit two-up across the width.

"Lined" adds 30% on this estimator because lining fabric is usually cut from the same length, plus you'll need fabric for facings and interfacing.

Buttonhole rules of thumb

• Buttonhole length: button diameter + 3 mm (1/8″) for ease. Add another 2–3 mm for thick or domed buttons.
• Top button position: 1.5–2 cm below the collar stand on a shirt; 5–7 cm below the neckline on a dress.
• Bottom button: 6–8 cm above the hem to prevent the placket gaping at the bottom.
• Spacing: 6–8 cm between buttons on shirts, 8–10 cm on dresses, closer at the bust.
• Stress points: always place a button at the bust line and waistline if there's tension there.

Choosing a sewing machine needle

Sizing is shown European/American (e.g., 80/12). Bigger numbers = thicker needles. Match needle weight to fabric weight: 70/10 for fine fabrics, 80/12 for typical wovens, 90/14 for thicker fabrics, 100/16 for denim and canvas.

Type matters more than brand. Schmetz, Organ, and Klassé needles are all interchangeable in home machines (system 130/705 H). Choose the right type — Universal, Stretch, Microtex, Jeans, Leather, Embroidery — for your fabric and project.

Change frequently. A dull needle is the single most common cause of skipped stitches, fabric snags, and noisy sewing. Aim for a fresh needle every 6–8 hours of active sewing, or at the start of every new project.

Choosing thread

Match weight to fabric: 50–60 wt for everyday construction, 40 wt for medium fabrics, 30 wt for topstitching, 12–28 wt for decorative work. Heavier thread on lightweight fabric will pucker; finer thread on heavy fabric will break.

Polyester sew-all (Gütermann, Mettler) is the everyday workhorse — strong, doesn't shrink, works on most fabrics from chiffon to denim. Cotton shrinks with the fabric and behaves more naturally in cotton-on-cotton sewing, which is why quilters tend to prefer it.

Top and bobbin threads should usually match. On very fine fabrics, a finer bobbin thread reduces bulk in seams; on dense topstitching, a thinner bobbin saves the bobbin from running out mid-row.

Choosing stitch length

2.5 mm is the everyday default — works for most construction sewing on woven fabrics. Shorter (1.5–2 mm) for stretchy fabrics and stress points; longer (3–4 mm) for topstitching, basting, and gathering.

Zigzag has both width and length: width = how wide the swing, length = how dense the stitches. A small zigzag (1 mm wide × 2.5 mm long) lets seams stretch on knit fabrics. A wide, dense zigzag (3–5 mm wide × 0.4 mm long) is "satin stitch" — used for buttonholes and decorative work.

Tension test: a balanced stitch shows no thread on the wrong side from the top thread, and vice versa. If you see one or the other, adjust upper tension first (looser if top thread is showing on the underside, tighter if bobbin thread is showing on top).

Reading care labels

Symbols are international — ISO 3758 means the same icon carries the same meaning regardless of where the garment was made or sold. A tub means washing, a triangle means bleaching, a square means drying, an iron means ironing, and a circle means professional dry cleaning.

A cross through any symbol means "do not". Crossed-out tub = do not wash. Crossed-out triangle = do not bleach. Crossed-out iron = do not iron.

Dots inside symbols indicate temperature levels: more dots = higher heat. One dot is the gentlest, three dots is the highest. Numbers (e.g., "30" inside a tub) give exact maximum temperatures.

About pillow covers

Negative ease (cutting slightly smaller than the form) gives a plump, well-filled look. For a 45 cm pillow, cutting 43 cm + seam allowance ensures the cover snaps snugly over the form. Zero ease gives a slack cover; positive ease looks loose.

Envelope back overlaps two rectangles on the back so the form slides in. Each back rectangle is roughly 60–65% of the front width to give a generous overlap (typically 10–15 cm).

Zipper back is one full-size rectangle with the zipper inserted across the back. Slightly more sewing but a cleaner look.

Drop guidelines

• Casual everyday: 20–30 cm drop. Comfortable for diners; doesn't snag on knees.
• Formal dinner: 30–40 cm drop. Looks polished; reaches lap level.
• Floor-length (banquet, weddings): 75 cm drop or table-height-minus-1cm. Skirts the floor.

For circular tables: total cloth diameter = table diameter + 2 × drop. The calculator above is for rectangular tables only.

How to read a pattern

Pattern pieces use a small set of symbols that, once you know them, make it possible to read any commercial pattern without instruction. Always lay the grain line parallel to the selvedge first, then check notches and dots match between adjacent pieces, and follow seam allowances precisely (commercial patterns mostly use 1.5 cm / 5/8″, indie patterns vary — check the envelope).

Choosing the right seam

Pick the seam to match the fabric and the wear:

• Plain seam for everyday garments where the inside isn't visible — finish the raw edges with overlocking, zigzag or pinking.
• French seam on sheers, lightweight fabrics, and unlined garments where you'll see the inside (e.g. a drawstring-bag interior).
• Flat-felled seam on jeans, work shirts, and anything that needs strength and won't fray — both raw edges enclosed.
• Bound seam for unlined jackets and refined finishes — the seam allowance is wrapped in bias tape.

Choosing the right hem

• Narrow / baby hem on lightweight fabrics where bulk would show — silk, chiffon, voile.
• Double-fold hem on most cotton garments; sturdy and looks tidy.
• Blind hem on tailored skirts, trousers and dresses where you don't want to see stitching from the outside.
• Rolled hem (with a serger or rolled-hem foot) for formal-wear edges, scarves, and decorative finishes.
• Lettuce hem for stretchy knits where you want a curly, decorative edge.
• Faced or bound hem for curved hems where a fold-up wouldn't lie flat (like a half-circle skirt).

How Roman blinds fold

Standard Roman: the blind divides into equal sections separated by rod pockets. When raised, each section stacks on top of the one below, creating concertina folds. The bottom section is usually the same as the others.

Cascading Roman: sections get progressively larger toward the top, so when raised the bottom edge of each fold sits below the next, creating a scalloped 'waterfall' look.

Typical fold height is 20–30 cm. Smaller folds look more tailored but use more rods.

About box cushions

A boxed cushion has three pieces: a top, a bottom, and a gusset (boxing strip) running around the perimeter. The gusset gives the cushion its depth.

Negative ease (cutting slightly smaller than the form) produces a snug, well-filled look. 1–2 cm is typical for new foam; older flatter cushions can take 0 to +1 cm.

Zipper goes along one back edge of the gusset for easy form removal. Some makers run it around three sides for easier insertion.

How the maths works

Each main panel (front + back) is cut as a single rectangle of: width + depth wide × height + depth/2 + hem allowance tall. The depth gets boxed at the bottom by cutting out a small square from each lower corner and stitching the cut edges together.

Handles are cut as long strips of (2 × finished handle width + 2 × seam allowance) wide × (2 × handle drop + 5 cm) long. Fold lengthwise, sew, turn, top-stitch.

For a lined tote, cut the same pieces a second time in lining fabric. Total fabric roughly doubles.

How the FBA / SBA maths works

Pick your pattern size by your HIGH BUST, not your full bust. Patterns are drafted to fit a standard cup size (usually B) — choosing by full bust gives you a top that's too wide at the shoulder and armhole.

The adjustment = (your bust − high bust) − (pattern's standard difference), then divided by 2 (the adjustment applies to ONE side of the bodice front; the other side mirrors).

For a B-cup pattern, the standard high-to-full difference is 5 cm (2″). C-cup patterns assume 6.5 cm (2.5″); D-cup patterns 7.5 cm (3″).

Always swatch first

Knit a 15×15 cm test square in the same yarn, needles and stitch pattern as your project. Wash and dry it the way you'll wash the finished piece. Then measure stitches and rows over the central 10 cm — edges distort the count.

If your stitches-per-10cm is fewer than the pattern, your knitting is looser → use smaller needles. More stitches = tighter → use larger needles. Or use this calculator to adjust the pattern's instructions to your gauge.

How to tell a yarn weight

Most yarn ball bands carry both the Craft Yarn Council weight symbol (0–7) and a description (lace, fingering, DK, etc.). When in doubt, count wraps per inch (WPI): wrap the yarn snugly around a pencil or ruler, count how many wraps in 2.5 cm. The result narrows down the category quickly.

Which size do I use?

The yarn label gives a recommended hook size. As a rough rule: for a tighter, neater fabric pick a hook one size smaller than recommended; for a softer drape pick one size larger. Always swatch.

UK and US numbering systems are different — UK uses numbers (older / metric-influenced), US uses letters. They don't map one-to-one because some sizes only exist in one system.

Typical fabric weights

About flying geese

A flying geese unit is a rectangle made from one large central triangle (the "goose") and two smaller corner triangles (the "sky"). The standard ratio is 2:1 — twice as wide as tall.

The no-waste 4-at-a-time method uses one large square plus four small squares to produce four geese units in one go, with no fabric wasted in trimming triangles. Cut sizes:

• 1 large square: finished width + 1¼″ (this becomes the 4 large triangles)
• 4 small squares: finished height + ⅞″ (these become the 8 small corner triangles)

About QSTs

A quarter-square triangle (also called an hourglass block when made with two colours) is a square divided into four right triangles meeting at the centre. Two common construction methods:

• Two-colour hourglass: make 2 oversized HSTs, place them RST with seams pressed in opposite directions, cut on the diagonal opposite to the HST seam, sew → 2 QSTs. Cut size = finished + 1¼″.
• Four-colour QST: 4 different fabric squares of finished + 1¼″ each. Pair, sew like an HST, then re-pair and sew like a QST. Yields 4 QSTs with all four colours showing.

The bias edges around the perimeter of a finished QST are notoriously stretchy — handle gently, starch helps.

About pre-cuts

• Jelly roll: 40 strips of 2.5″ × WOF. Total ≈ 2¾ yards of fabric (40 × 2.5″ ÷ 36″).
• Charm pack: 5″ × 5″ squares, usually 42 per pack.
• Layer cake: 10″ × 10″ squares, usually 42 per pack.
• Honey bun: 1.5″ strips × WOF, usually 40 strips.
• Mini charm: 2.5″ × 2.5″ squares, usually 42 per pack.

Choosing elastic

• Braided elastic: stretchy, but narrows when stretched. Best inside casings (waistbands).
• Knit / softfeel elastic: doesn't narrow when stretched. Better for stitched-on applications (sewing directly to the fabric).
• Woven elastic: firmest, doesn't narrow. Used in heavier garments and waistbands that need to hold shape.
• Fold-over elastic (FOE): pre-creased, for binding raw edges on knits — common on swim and dance wear.
• Picot-edge elastic: decorative scalloped edge for visible-elastic finishes (lingerie, pyjamas).

Test before cutting: elastic varies a lot in stretchiness. Wrap a piece around the body part with comfortable tension, mark it, and use that length minus a centimetre or two if it feels loose.

Sizing

Zippers are sized by the width of the closed teeth in millimetres — #3, #5, #7, #10, etc. Heavier zippers have larger teeth.

• #3 — standard dressmaking, lightweight to medium garments. Most invisible zippers are #3.
• #5 — denim, jackets, bags, most mid-weight applications.
• #7 / #8 — heavy jackets, outerwear, structured bags.
• #10 — coats, sleeping bags, heavy-duty applications.

Tips for accuracy

• Don't measure yourself in the mirror — you'll subconsciously suck in. Have someone else do it, or check in profile.
• Tie a string at your natural waist before measuring (it's not always where your trouser waistband sits). The tape stays put on the string.
• Stand naturally — feet together, weight even, don't hold your breath.
• Tape level all the way around — easy to drift up or down at the back.
• Re-measure every 6 months or after weight changes. Bodies aren't static.

Compatibility

Most modern domestic machines use snap-on feet — push the foot under the shank and lower the lever; the foot snaps onto place. Older machines use screw-on feet, where the entire shank assembly is replaced.

Branded feet (Bernina, Pfaff, Janome, Brother, Singer) are not always interchangeable. Generic "low-shank" feet fit most low-shank machines (most Brother, Janome, Singer); "high-shank" fits Bernina and some industrials. Check your manual.

Choosing a quilt size

Most "bed quilts" finish slightly bigger than the mattress — at least 15–25 cm overhang on each side covered (top, sides, foot). Pillow tuck is optional; some quilts include extra at the head, others don't.

If your goal is a quilt that covers the whole bed and reaches the floor, add the box-spring depth × 2 to the width and once to the length (since the head is usually against a wall).

Working with blocks

Most blocks are sized by their finished dimensions (the size in the quilt after seam allowances are sewn). Unfinished size is finished + ½″ for 1/4″ seams on each side.

Many blocks use sub-units — HSTs, QSTs, flying geese, four-patches, nine-patches. Get those right and the blocks come together easily. Use the dedicated calculators for accurate cut sizes.

How to measure for a bra

• Underbust (band): tape level around your ribcage just under the breast tissue, snug but breathing comfortably.
• Bust: tape across the fullest part of the bust, level around the back. Wear a non-padded bra.
• Cup size = bust − underbust. 1″ (2.5 cm) difference = A, 2″ = B, 3″ = C, 4″ = D, 5″ = DD, 6″ = E, etc.

Note: sizing varies between brands and even between styles within a brand. This is a guide — always try things on.

What to budget for

• Fabric: the biggest line. Quality dressmaking fabric is £12–25/m; specialty fabrics (silk, wool) £20–60/m.
• Lining — only some garments need it (jackets, skirts, lined dresses). Budget £4–8/m for polyester lining.
• Notions — interfacing £2–5, invisible zipper £2–3, separating zipper £4–8, buttons typically £0.50–£2 each, thread £2–3 per reel.
• Pattern — Big 4 PDF/paper patterns £8–15, indie patterns £12–18, multi-pack patterns can offer savings.
• "Cost of sewing" — many sewists discover that a one-off garment costs more than retail. The value is in fit, fabric quality, and the satisfaction of having made it yourself.

Choosing a children's size

For kids, height is more reliable than age. Two 6-year-olds can have wildly different builds. Measure the child's height first, then look across the table.

Children grow into seam allowances quickly — many parents add a centimetre to the chest and length when cutting, so a garment fits when made and continues to fit a few months later.

Rules of thumb

• Standard formula: button diameter + 3 mm (1/8″). Gives just enough ease for the button to slip through without strain.
• Thick buttons: add 2–3 mm extra so the buttonhole accommodates the depth.
• Domed buttons: add 3–5 mm — the button needs more room to tip through.
• Shanked buttons: add the shank height to the calculation.
• Knit fabric: the buttonhole stretches with the fabric, so subtract 2 mm to keep it snug.

How to spot a knit fabric

Knits are made by interlooping yarns, like hand-knitting on a tiny scale. Pull a knit fabric across the grain — it stretches. Wovens (interlocking yarns at right angles) don't stretch on the grain.

The cut edge of a knit doesn't fray (it curls instead). The cut edge of a woven frays. That's the quickest at-a-glance test.

Choosing interfacing

• Match the weight to your fabric. Lightweight interfacing on chiffon, heavyweight on coats. Mismatch = stiff or floppy collar.
• Match the type to your fabric. Knit fabric needs knit or weft-insertion interfacing — fusible woven interfacing destroys stretch.
• Always test on a scrap first. Fusing temperature, time, and pressure all matter. A pre-test prevents a ruined garment.
• Sew-in interfacing stays softer and tailors better, but takes longer. Best for couture-quality garments and silk.

How to measure

• Bust: across the fullest part, around your back, loose enough to slip a finger under the tape.
• Waist: the narrowest part of your torso (often just above the navel). Tie a piece of elastic or string around and let it settle naturally.
• Hips: across the fullest part of your hips/seat, usually 18–22 cm below the waist.

Always use the body measurement that's closest; if your bust and hips fall in different sizes, grade between them on the pattern.

How the maths works

The waist of a circle skirt is the inner circle of an annulus. Its radius is calculated from waist = 2π × r for a full circle. For partial circles, the waist arc spans only part of a full circle, so the radius gets bigger to give the same waist measurement:

• Full circle (360°): r = waist ÷ (2π) ≈ waist ÷ 6.28
• Three-quarter circle (270°): r = waist × 4 ÷ (3 × 2π) ≈ waist ÷ 4.71
• Half circle (180°): r = waist ÷ π ≈ waist ÷ 3.14
• Quarter circle (90°): r = waist × 2 ÷ π ≈ waist ÷ 1.57

Outer radius = waist radius + skirt length + hem allowance. To cut the skirt you need a square (or strip) of fabric at least the diameter of the outer circle.

About quilt binding

Standard double-fold binding is cut at 2.25–2.5″ wide on the straight grain (cross-grain), folded in half lengthwise, and sewn to the front of the quilt with a 1/4″ seam, then folded over to the back and stitched down.

The 25 cm / 10″ buffer in the calculation covers the four corner mitres (which each consume ~1.5–2″) and the diagonal joining seams between strips.

Bias binding (cut at 45° to the grain) is gentler around curves but uses more fabric. Use the bias binding calculator for that.

About HSTs

Three common construction methods, each with its own cut formula:

• 2-at-a-time: Cut size = finished + 7/8″. Pair two squares RST, draw one diagonal, sew 1/4″ on each side, cut on the line. Most accurate but slowest.
• 4-at-a-time: Cut size = finished × √2 + 1.25″. Pair two squares RST, sew 1/4″ around all four sides, cut on both diagonals. Bias edges on all four sides — handle carefully.
• 8-at-a-time: Cut size = finished × 2 + 1.75″. Pair two squares RST, mark both diagonals, sew 1/4″ each side of both diagonals, cut on both diagonals AND in half horizontally and vertically. Fastest but trims the most.

How to choose fullness

• 1.5× — flat or eyelet curtains: Very flat hang. Used for sheers on a tension wire or simple eyelet curtains.
• 2× — standard pencil pleat: The classic UK curtain look. Good fullness without excess.
• 2.5× — pinch pleat / pencil pleat (luxe): Generous, drapes elegantly. Best on heavier fabrics.
• 3× — very full / wave: Sheers, voiles, and dressy formal curtains. Drapes with deep waves.

Pattern repeat: if your fabric has a print that repeats every 60 cm, each curtain length must be cut at the next multiple of 60 cm so prints line up at the top of each panel. The calculator adds this automatically.

Choosing a gathering ratio

• 1.5× — subtle gathers; good for waistbands on heavier fabric.
• 2× — the everyday standard; works for most skirts and ruffles in cotton, linen and viscose.
• 2.5× — full, bouncy gathers; good for skirt tiers, ruffled hems, and gathered yokes.
• 3× — very full; needed for sheer fabrics (chiffon, voile) where you want visible volume despite the lightweight drape.

How to gather: sew two parallel rows of long basting stitches (5 mm) inside the seam allowance, leaving long thread tails. Pull both bobbin threads simultaneously to draw the fabric up evenly.

How to test

Lay the fabric flat (don't stretch it). Mark a known length — 10 cm is easy. Then stretch the fabric across that section as far as it will go comfortably (not maximum stretch, just normal wear). Measure the stretched distance.

For accuracy, test the cross-grain (selvedge to selvedge) which is usually the stretchiest direction. Test the lengthwise grain too if your pattern needs four-way stretch.

Stretch percentage classification:

• Light stretch (0–25%): stable knits, French terry, ponte. Most loose-fit patterns.
• Medium stretch (25–50%): jersey, interlock. The standard for fitted knit garments.
• Heavy stretch (50–100%): rib knits, lycra blends. For tight tops, leggings.
• Four-way stretch (100%+): swimwear, dancewear, activewear lycra.

About backing

Overhang: the backing should extend 3–4″ (8–10 cm) beyond the quilt top on every side. This gives room for shifting during quilting and for the long-arm clamp.

Pieced backing: when the backing is wider than 42″ standard fabric, pieces are joined with a centred seam (or off-centre to avoid the bullseye look). Most quilters add 4″ of seam allowance into the calculation.

Wide-back fabric (108″/274 cm) avoids piecing entirely for most quilts under king size. Costs more per metre but saves time and gives a seamless back.

How pleats consume fabric

• Knife pleat: each pleat takes visible width + 2 × depth of fabric, all folded the same way. Total ratio depends on your depth-to-width choice.
• Box pleat: a "knife pleat facing right + knife pleat facing left, meeting at the back". Each box takes visible width + 2 × depth, so similar consumption to knife pleats with same dimensions.
• Inverted box pleat: mirror image of box — the meeting point is on the front, hidden seam at the back. Same fabric consumption as a box pleat.
• Cartridge pleat: tight rolled pleats (think Tudor sleeves). Roughly 4× ratio depending on cartridge size.