“How much fabric do I need?” is the question that decides whether a project ends in triumph or in a second trip to the fabric store for a dye lot that no longer matches. This Fabric Calculator turns your project’s finished width and length, the fabric’s usable width and any pattern repeat into the exact yardage to buy — counting panels, rounding cuts to the repeat, and showing its working.
Worked Example: A 90 × 72 Inch Project on 45-Inch Fabric
The calculator first counts panels: covering a 90-inch width with 45-inch fabric takes ⌈90 / 45⌉ = 2 panels. Each panel is cut 72 inches long (no pattern repeat to match, so no rounding), giving 2 × 72 = 144 inches of fabric = 144 / 36 = 4.00 yards. Now add a pattern repeat and watch the yardage grow teeth: with a 12-inch vertical repeat, each cut must be lengthened to a whole number of repeats so the pattern aligns across panels — ⌈72 / 12⌉ × 12 = 72 inches here (already a multiple, so no change), but a 70-inch panel would become ⌈70 / 12⌉ × 12 = 72 inches, and the two extra inches per panel are the invisible tax every patterned project pays. Real projects add two more allowances this example omits for clarity: seam and hem allowances belong inside the project dimensions you enter (enter the cut size, not the finished size — for curtains, finished length plus hem and heading allowances; for a quilt top, the top’s dimensions plus a margin for quilting shrinkage and squaring), and a safety margin of 10% or an extra quarter-yard covers cutting errors, shrinkage in pre-washing (cottons commonly shrink 3–5% in length) and the pattern-placement fudge that no formula foresees. The store cuts in eighths of a yard (0.125) at most counters, so round the final figure up to the next eighth — 4.00 yards stays 4, but 3.87 becomes 4.0 in practice, never 3.75.
The Logic: Panels, Cuts and the Direction of Grain
Every flat fabric calculation is the same three moves. Panels: fabric comes in fixed widths (quilting cotton 44/45 in, apparel 45 or 60, home-decor 54, upholstery 54–60), and anything wider than the bolt is sewn from ⌈project width / fabric width⌉ lengths joined side by side. Cut length: each panel is cut to the project length, adjusted upward to a whole pattern repeat when the design must match at the seams — the repeat is measured along the length (the vertical or “railroad” repeat in decor terms) and the rounding is always up, because a motif cut mid-phase cannot be un-cut. Total: panels × cut length, converted at 36 inches to the yard. Grain direction is the assumption holding this together: panels are cut along the lengthwise grain (parallel to the selvage), which is why length is consumed per panel rather than width. Crosswise cutting (“railroading” in upholstery) swaps the roles for wide, short projects on wide fabric and can save real money on, say, a 100-inch-wide, 30-inch-long valance — but it changes drape and pattern orientation, so it is a deliberate design decision, not a default. Nap and one-way prints impose the same discipline from another direction: all panels must be cut facing the same way, which forbids the fabric-saving trick of flipping alternate panels and is priced into the repeat allowance when the fabric has both.
Project Notes: Quilts, Curtains, Apparel and Upholstery
Quilts use this page twice: once for the top if it is whole-cloth or large panels, and once for the backing, which conventionally needs the top’s dimensions plus 4 inches of overhang on every side for the longarm or basting — enter the enlarged size, and prefer 108-inch backing fabric when the quilt is wide, because a single panel at 108 beats three seamed panels at 45 for both money and flatness. Pieced tops are a different arithmetic (block counts × block yardage) that this area-based tool approximates only for borders and sashing. Curtains hide their real dimensions in fullness: the “project width” to enter is not the window width but the gathered width — 2 to 2.5 times the rod width for standard fullness — and the length must include hem (often 8 inches doubled) plus heading; a 48-inch window at 2× fullness is a 96-inch project width before the calculator ever sees it. Apparel follows pattern envelopes, whose yardage tables already encode layout efficiency for standard sizes; use this calculator for self-drafted garments, alterations of layout (narrower fabric than the envelope assumes — recheck the envelope’s second column before substituting), and border prints. Upholstery adds matched-pattern discipline at its strictest and three-dimensional waste; treat the output as a floor and add 15–20% for arms, welting and the inevitable mis-cut.
Standard Widths and Two More Worked Projects
Keep the common usable widths at hand, because the panel count — and therefore the bill — hinges on them: quilting cotton 44–45 in; apparel linen and shirting 54–60; denim and canvas 58–60; silk charmeuse 45 (some 55); home-decor cotton and linen blends 54; upholstery 54–62; fleece 58–60; tulle and extra-wide backing 108. A width upgrade is often the cheapest yardage cut in the project: moving a wide project from 45-inch to 60-inch goods can erase an entire panel. Project two — quilt backing: a 68 × 88 in twin quilt needs backing at 76 × 96 (top plus 4 in of overhang per side). On 45-inch fabric, panels = ⌈76 / 45⌉ = 2, cuts of 96 in: 192 in = 5.33 yards. On 108-inch backing fabric it is a single 96-inch cut: 2.67 yards — half the yardage, no seam, usually the better buy despite the higher per-yard price. Project three — a table runner: 16 × 72 in finished, cut 18 × 74 with allowances, on any 45-inch fabric: one panel, one 74-inch cut = 2.06 yards, bought as 2.125 yards at the counter’s eighth-yard grid. Notice the runner’s lesson: narrow projects on standard fabric strand the rest of the width, which is why quilters plan the matching napkins and placemats to colonize the offcut — the calculator gives the runner’s yardage, and the width column quietly tells you a second project is hiding in it.
Pre-Washing and Shrinkage: Buy for the Fabric You Will Have
Natural fibres shrink, mostly in length, and the shrinkage belongs in the purchase, not in a regret afterward. Typical first-wash length shrinkage: quilting and apparel cottons about 3–5%, linen 3–5% (sometimes more, and it softens as it shrinks), rayon up to 10%, while polyester barely moves. The adjustment is a simple multiplier on the computed yardage: the example’s 4.00 yards in a 4%-shrink cotton should be bought as 4.00 × 1.04 = 4.16 — 4.25 yards at the eighth-yard grid — then pre-washed before cutting, so the project’s dimensions are cut from the fabric’s settled state. Width shrinks less than length, which is another reason the calculator’s panel math stays valid after washing while the cut lengths carry the risk. When a project mixes pre-washed and unwashed components (a washed top against an unwashed batting or backing), shrink the unwashed partner in the plan as well, or the first wash of the finished piece will pucker along every seam where the two disagree.
Common Mistakes
Entering finished dimensions instead of cut dimensions (allowances forgotten are inches stolen from every edge). Forgetting that fabric width is usable width — selvage to selvage minus the unprinted edges, often an inch less than the bolt’s nominal width. Ignoring the repeat on patterned fabric, then discovering at the cutting table that the panels cannot align. Buying the exact computed yardage with zero margin: one miscut or an off-grain bolt end and the project stalls for want of a quarter-yard that cost little at the first visit — fabric stores and dye lots are unforgiving about second chances. And mixing units mid-project: patterns in centimetres, bolts in inches, this page in inches throughout — convert once, at entry.
Related Tools
Continue with the Toilet Paper Calculator, the Reading Speed Calculator, the Shoe Size Conversion, or browse the full Everyday Life Calculators hub.
Frequently Asked Questions
How do I calculate how much fabric I need?
Panels = project width ÷ fabric width, rounded up. Yardage = panels × cut length (rounded up to a whole pattern repeat) ÷ 36. The example: 90 in wide project, 45 in fabric → 2 panels × 72 in = 4.00 yards.
How much extra should I buy for pattern matching?
The calculator already rounds each cut up to a full repeat. On top of that, buy about 10% extra (or an additional quarter to half yard) for shrinkage, squaring the grain and cutting insurance — especially for one-way prints and nap fabrics that forbid flipping panels.
What fabric width should I enter?
The usable width between selvages, not the nominal bolt width: quilting cotton is typically 44–45 in usable, apparel 45 or 60, home decor 54. When in doubt, measure the bolt or subtract an inch from the label figure.
Why does my curtain calculation seem too small?
Fullness. Curtains are gathered to 2–2.5× the rod width, and the length needs hem and heading allowances. Enter the gathered width and the cut length (finished length + allowances), not the window’s raw dimensions.
How much backing does a quilt need?
Enter the quilt top’s dimensions plus about 4 inches on every side (8 total per dimension) for quilting overhang. Wide 108-inch backing fabric often covers a large quilt in a single panel.
Can I cut panels crosswise to save fabric?
Sometimes — “railroading” suits wide, shallow projects, but it rotates grain and pattern direction, changing drape. It is a design decision to make deliberately, not an arithmetic default; this calculator assumes standard lengthwise cutting.