Sewing, knitting and crochet calculator
How much fabric — pattern pieces packed on the fabric width (folded or single, nap, seam allowance) — plus quick estimates for skirts, curtains and cushions, bias and binding, knitting and crochet gauge and resizing, CYC yarn weights and yarn quantities, increasing or decreasing evenly across a row, and grading measurements between sizes.
Added
How to use it
Practical arithmetic for sewing, knitting and crochet, in centimetres and metres or inches and yards (remembered).
How to use it
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Fabric layout. List the pattern pieces as rectangles (width across the fabric × length along the grain, how many to cut, and whether a piece is cut on the fold), the usable fabric width, and single layer or folded lengthwise (selvedges together: every piece is cut as a mirrored pair, a fold piece once with its centre on the fold). Optionally allow 90° turns where the grain does not matter, mark the fabric as nap or one-way (no turning), add seam allowance to every edge, pre-wash shrinkage and an allowance for straightening the ends. The tool packs the pieces, draws the cutting layout and gives the length to buy, rounded up to 0.1 m or ⅛ yd. Press ⛶ Full screen (or
F) for a large layout; Esc leaves. -
Quick estimates. A circle or half-circle skirt (waist radius = waist ÷ 2π or ÷ π; one square, or quarter panels when the fabric is too narrow), a gathered skirt (fullness × waist, seamed from fabric widths), a pair of curtains (track × fullness in fabric widths, drops rounded up to whole pattern repeats), and an envelope cushion cover.
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Bias & binding. Continuous bias from a square (about S² ÷ strip width), the square needed for a length, and straight strips across the width for a binding.
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Gauge & yarn. Stitches and rows per 10 cm (or 4 in) to per-unit and to counts; a pattern’s stitch count re-gauged to yours; the Craft Yarn Council weight categories with needle and hook sizes; yarn quantity from a weighed swatch; and rough planning ranges by project.
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Increase evenly. “Increase 13 stitches evenly across 87”: the instruction, worked flat (half a section at each end, so nothing sits on the edge) or in the round, for knitting (M1, K2tog) or crochet (2 sc in a stitch, sc2tog). Two forms: evenly spread, and an easier-to-follow version with the larger sections together. 87 + 13 flat gives
K3, M1, (K7, M1) 9 times, (K6, M1) 3 times, K3. -
Grading. Type your pattern’s size chart, list the pattern measurements you want to move, which body measurement each follows and its share of the change (a half front on the fold carries ¼ of a girth change), and read them for every size.
How it works
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Layout: a skyline bottom-left packer — pieces sorted tallest first, each placed at the lowest position where it fits (fold pieces only against the fold). The tests check known layouts (four 50 × 70 cm pieces on 150 cm fabric need 140 cm), that pieces never overlap or leave the fabric, and that the length is never less than the area allows.
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Even spacing: k changes sit at positions round((j + ½) · n ÷ k) when flat, round((j + 1) · n ÷ k) in the round, so sections differ by at most one stitch. The tests check the standard forms —
(K8, M1) 8 timesfor 64 + 8 in the round,(K6, K2tog) 8 timesfor 64 − 8, and the amigurumi rounds 6 → 12 → 18 → 24 ((sc in next st, 2 sc in next st) 6 times) — and that every stitch is accounted for. -
Gauge: stitches = width × gauge ÷ 10; your count = pattern count × your gauge ÷ pattern gauge.
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Grading: value + (body in the new size − body in the pattern size) × share.
Limits
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Pieces are rectangles. Real pattern pieces are shaped and nest, so a careful layout can use less fabric; nap and one-way prints prevent head-to-tail nesting, which this packer cannot model either way. Matching plaids and stripes needs extra. Use it as a buying estimate.
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Garment estimates are geometry with fixed hems (2 cm skirt hem, 1.5 cm seams, 15 cm curtain hems), not patterns.
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Yarn planning ranges are rough figures from typical patterns; a swatch is better, the pattern’s figure best.
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The example size chart is illustrative only; every company grades differently. Linear grading does not move necklines, armholes or shoulders the way professional grade rules do.
Related: recipe scaler, cut list optimiser (the same problem for sheet goods), unit converter, glaze chemistry, kiln and firing.
Sources: Craft Yarn Council, Standard Yarn Weight System (yarnstandards.com) for the weight categories, gauge ranges and needle and hook sizes.
Linking to an example
Share link copies a URL with your settings — your size chart and measurements stay in your browser.
Lengths in links are in centimetres. Pieces are written name:width x length x count, with f for
cut on the fold — for example
?fw=115&lay=single&pcs=Panel:50x60x4.
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Fabric width; |
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Pattern pieces, e.g. |
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Quick estimate ( |
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Bias square side, strip width, length needed |
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Gauge (sts, rows per 10 cm); pattern and your gauge; pattern stitch count; CYC weight 0–7 |
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Stitches, changes, |
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Grading: pattern size and size to make |
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Presets (?example=<name>):
example= |
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