How does the calculator work out how much fabric I need?

It uses a strip-packing algorithm. Pieces are sorted tallest-first, then placed one by one across the fabric width. When a piece does not fit in the remaining width of the current row, a new strip (cutting row) is started. The total fabric length equals the sum of all strip heights plus seam-allowance gaps between strips, and a cutting buffer percentage is added on top. The result is then rounded up to the nearest ⅛ yard (or 0.1 m).

Why is the yardage rounded to the nearest ⅛ yard?

Fabric is sold in ⅛-yard increments at most fabric shops and online retailers. Rounding up to the nearest ⅛ yard ensures you always buy enough and never end up a thread short at the cutting table.

Should I enter finished (sewn) dimensions or cut dimensions?

Enter cut dimensions — the size you actually cut from the fabric before sewing, including seam allowances. If your pattern already prints cut lines (as most commercial patterns do), use those. The seam-allowance setting in the calculator adds a small gap between strips to account for layout margin, not to inflate piece sizes.

What fabric width should I use?

Use the actual usable width of your fabric after removing selvedges — typically 1–2″ less than the stated bolt width. Common bolt widths are 44/45″ for quilting cotton and shirting, 54–60″ for apparel wovens and stretch knits, and 108″ for wide quilt backing. When in doubt, go with 44″ for quilting and 58″ for dressmaking and you will rarely be caught short.

Does the calculator account for nap, one-way prints, or grainline?

Not automatically. The strip-packing layout assumes pieces can be placed in any horizontal position across the width of the fabric. For nap fabrics (velvet, corduroy) or one-way prints, all pieces must run in the same direction, which means pieces cannot be flipped end-for-end — increase the cutting buffer to at least 10–15% to compensate, or add a separate strip for each directional piece.

How much extra fabric should I add for a print repeat?

A common rule is to add one full repeat length per major pattern piece. For example, a 6″ repeat on a blouse with three major pieces means buying roughly 18″ (0.5 yd) extra on top of the base yardage. Use the buffer percentage field as a quick proxy: a 10–15% buffer usually covers a small repeat; large repeats (12″ or more) deserve manual addition.

Can I use this for quilts?

Yes. Enter each unique cut piece (e.g. 4.5″ × 4.5″ HST square) with its cut dimensions and total quantity. Use a 44″ or 40″ fabric width (after pre-wash shrinkage and selvedge removal). The calculator will show how many strips of each piece fit across the width and total the length needed per fabric colourway.

Fabric Yardage Calculator

A fabric yardage calculator that turns a list of pattern pieces into a precise yards-to-buy figure — rounded up to the nearest ⅛ yard (or 0.1 metre) and backed by a visual strip layout. Useful for dressmaking, quilting, home dec, and any project where you need to translate a cut list into a shop order before you reach the cutting table.

How it works

The calculator uses a strip-packing approach that mirrors how a real cutter lays fabric on a table:

All pieces are sorted by cut height — tallest first — so the most demanding strip heights are handled before the fabric runs out.
Each piece is placed as far left as possible in the current horizontal strip (row across the bolt). When a piece does not fit in the remaining width, a new strip opens directly below.
The total required length equals the sum of all strip heights, plus a small seam-allowance gap between each strip, plus a percentage buffer for print repeats, notch clearance, or accidental mis-cuts.

This is a well-known First-Fit Decreasing Height (FFDH) bin-packing approximation. For rectangular pieces without nap or directional grain it typically comes within 5–10% of a hand-optimised layout — accurate enough for buying fabric and far better than guessing.

The rounding rule

Fabric is sold in ⅛-yard increments (4.5 inches) at the cutting table. The calculator takes the raw length in inches, adds the buffer, then applies:

Yards to buy = ⌈ (raw inches × (1 + buffer)) ÷ 36 × 8 ⌉ ÷ 8

The ceiling is taken on the nearest ⅛ yard so you always have a little in hand. In metric mode the result is rounded up to the nearest 0.1 m.

Worked example

Suppose you are sewing a simple A-line dress on 45″-wide cotton. Your pattern gives four cut pieces:

Piece	Width	Length	Qty
Front bodice	18″	24″	2
Back bodice	16″	22″	2
Sleeve	14″	20″	2
Waistband	40″	4″	1

With ⅝″ seam allowance gaps and a 5% buffer on 45″ fabric the calculator produces 2⅛ yards (approximately 1.97 m). A typical fabric store estimate “just get 2.5 yards” would be fine but wasteful; knowing you only need 2⅛ yards saves money — especially on expensive suiting or silk.

Quick reference: common bolt widths

Width	Typical use
36″	Voile, some interfacings, woven ribbons
44/45″	Quilting cotton, shirting, broadcloth
54″	Home-dec wovens, canvas, some wool
58/60″	Apparel knits, ponte, denim, bottom-weight wovens
72″	Fleece, polar fleece
108″	Wide quilt backing

Tips for accurate results

Enter cut dimensions, not finished (sewn) dimensions.
Remove selvedges before measuring — usable width is usually 1–2″ less than the stated bolt width.
For nap or one-way prints, increase the buffer to 10–15%; for very large repeats (12″ or more) add one full repeat length per colourway manually.
Pre-wash shrinkage on natural fibres typically takes 2–5% of length. Adding 5% buffer covers this for most projects.
When ordering online, round up to the nearest ¼ yard to allow for cutting inaccuracies at the warehouse.