Fabric Yardage Calculator

How much fabric do you really need?

Running out of fabric halfway through a project is a special kind of frustration, because fabric bought later may come from a different dye lot and never quite match, even when the colour name is identical. Buying far too much is the opposite waste, especially with expensive fabrics, where an extra yard can cost more than the pattern. Yardage is not mysterious: it is finished length plus allowances, times the number of pieces, converted from inches to yards, with a few adjustments for pattern repeats, fabric width, and nap. The calculator on this page handles the core arithmetic for panel-style projects such as curtains, adding an eight-inch hem and heading allowance per panel, and converting the result to both yards and metres, so you can order confidently in either system.

The reason allowances matter is that finished length is not cutting length. A curtain that hangs eighty-four inches long must be cut longer, because the bottom hem folds up several inches, the top heading folds down for a rod pocket or pleats, and the raw edges need a small turning allowance. Eight inches total is a reasonable standard for a lined or unlined curtain, though heavy interlined curtains may need more, and a rod-pocket top needs the pocket depth plus a heading allowance on top of that. Skimping on allowances to save fabric is false economy: a hem that is too narrow will not hang straight, and a heading that is too short cannot be fixed without a visible join.

Curtains: length, fullness, and panels

Curtain length is measured from the rod or track to where you want the curtain to end: to the sill, just below the sill, or to the floor, with floor-length curtains usually ending about half an inch above the floor so they do not drag and collect dirt. Puddled curtains, which deliberately pool on the floor, add several inches beyond floor length and need extra fabric and more frequent cleaning. Fullness is the other decision: a flat panel the exact width of the window looks skimpy, while a panel one and a half to two times the window width gathers into soft folds. Fullness multiplies width, not length, but it decides how many panels or widths of fabric you need, and for wide windows, that is where yardage grows fastest.

Panel count follows from window width and fabric width. Standard quilting and apparel fabrics are about forty-four to forty-five inches wide, while home-decor fabrics are often fifty-four inches or wider, and that width decides how many fabric widths make one curtain panel. A sixty-inch window at one and a half times fullness needs ninety inches of gathered width, which is two widths of forty-five-inch fabric, sewn together, per panel. The calculator works in panels, so if your panel itself needs two widths, double the panel count or calculate per width and multiply: the arithmetic is the same, but the distinction matters, and it is the most common source of under-ordering for wide windows.

Pattern repeats and nap: the hidden multipliers

Plain fabrics are forgiving, but patterned fabrics are not. A large pattern repeat, say twenty-four inches, means each cut length must be positioned so the pattern matches across panels, and the waste per length can approach a full repeat. The rule is to add one repeat per cut length beyond the first, or to buy an extra repeat per panel as insurance, and to check the pattern's direction: a one-way print cannot be flipped to save fabric, while a two-way print can. Nap is similar: velvets, corduroys, and some prints have a direction that must run the same way on every piece, or the pieces will look like different colours in different lights. Both factors increase yardage beyond the simple length-times-panels calculation, so for patterned or napped fabrics, add at least ten to fifteen percent, and more for large repeats.

Beyond curtains: dresses, cushions, and tablecloths

The same length-plus-allowance logic applies to other projects, with the allowances changing. A simple dress needs body length plus hem, sleeve length plus hem, and enough width for the bodice and skirt pieces, which is why dress yardage is usually quoted by size and fabric width on the pattern envelope, and why deviating from the pattern's layout risks coming up short. Cushion covers need the cushion's dimensions plus seam allowances and a closure overlap, and a round cushion needs a diameter-based calculation rather than a rectangular one. Tablecloths need the table size plus the desired drop on each side, plus a hem allowance, and an oval or round table needs a different formula again. In every case, the pattern envelope or a project-specific calculator is a better guide than a generic rule, and the calculator here is best for panel and length-based projects.

Fabric width: the number everyone forgets

Fabric width is printed on the bolt and on most online listings, but it is easy to overlook, and it changes everything. A project needing ninety inches of width takes two widths of forty-five-inch fabric but only one width of a one-hundred-and-eight-inch wide backing fabric, and the yardage differs accordingly. Wide fabrics are common for curtains, quilting backings, and table linens, and they can dramatically reduce the number of seams, which matters for the look of a curtain or a tablecloth. Always check the usable width, not just the nominal width, since selvedges are trimmed off and some fabrics lose an inch or two to a printed border. When in doubt, order based on usable width, and keep the selvedge measurement from the bolt label.

Buying smart: dye lots, shrinkage, and leftovers

Buy all the fabric for a project at once, from the same bolt if possible, and check the dye lot numbers match, because even the same colour name can vary between lots. Pre-wash washable fabrics before cutting if the finished item will be washed, since cotton can shrink three to five percent, and a curtain that fit perfectly before washing may end up noticeably short afterwards. Press fabric before measuring, since creases and folds distort length, and cut on a large flat surface with weights rather than pins where possible, to avoid stretching bias-cut pieces. Leftover fabric is not waste: save pieces large enough for repairs, matching cushions, or tiebacks, and label them with the project name and dye lot, because a future repair in matching fabric is worth far more than the yard it cost.

Measuring windows correctly

Measure each window separately, even in the same room, because houses settle and windows vary by an inch or more, and a curtain cut for one window may not fit its neighbour. Measure width at the rod, not at the glass, since curtains hang from the rod, and measure length from the rod to the desired endpoint at three points, left, centre, and right, using the longest for floor-length curtains and the shortest for sill-length ones, depending on which error you can tolerate. Note whether the rod is inside or outside the frame, whether there are obstructions such as radiators or handles, and whether the floor is level, since an uneven floor makes a floor-length curtain look crooked even when it was cut straight. A sketch with all three length measurements per window prevents most ordering errors.

A pre-order checklist

Before you order, run through this list: finished length per panel, number of panels, allowance per panel, pattern repeat and direction, nap direction, fabric width and usable width, shrinkage if pre-washing, and an extra margin of about ten percent for patterned fabrics or first-time projects. Add the margin as a separate line in your calculation, not as a vague hope, and if the total lands just over a whole yard, round up to the next half yard rather than down, since fabric is sold by the yard and a shortfall cannot be fixed by stretching. Keep the calculation with the receipt, so that if you need more later, you know exactly what you ordered and why.

When to ask the shop for help

Fabric shops cut fabric daily and will happily check a yardage calculation, especially for expensive or patterned fabrics, and many offer a cutting service that matches patterns across panels, which is worth paying for on a large curtain project. Take your measurements, your pattern repeat, and a photo of the window, and ask them to confirm the total before cutting, since a second pair of eyes catches the width mistake that a calculator cannot know about. Online shops cannot do this, so for a first large project, buying locally has a real advantage that offsets a slightly higher price. Either way, the calculator above gives you a number to start that conversation with, rather than a guess.

• Finished length is not cutting length: add hem and heading allowances.
• Buy all fabric at once, from the same dye lot.
• Add a repeat per length for large patterns, and allow for nap direction.
• Check usable fabric width, not just nominal width.
• Pre-wash washable fabrics before cutting to allow for shrinkage.

Fabric yardage is simple arithmetic plus a few honest allowances. Measure carefully, add the hem, count the panels, and use the calculator above to order enough fabric the first time, from the same dye lot, with no mid-project panic.