Calculate the Fabric Needed to Sew Simple Panel Curtains

Sewing your own curtains allows you to customize your own window treatments with the exact size and fabric you want. The first step for calculating how much fabric for curtains is needed is to measure the window.

Questions to Consider

Before picking up your fabric, think about how you would like your curtains to look. A few

• Do you want the curtain to go to the ceiling?
• Do you want the curtain to hit the floor, or is there a radiator that you want to leave unobstructed?
• How thick is the curtain rod you plan on using?
• Do you want the curtain in the window recess or will it cover the entire window and trim?
• How full do you want the curtain?

Calculate the Length of Each Panel

Use this formula to calculate the amount of fabric you'll need so the fabric is wide enough to create each panel:

Finished length + Header (facing) to the bottom of the rod + 1 inch to turn under 1/2 inch at each end of panel + Hem (allow 2 to 3 inches, depending on the weight of fabric) = Total fabric needed

This will give you the amount you need for each panel. 

A piece of lightweight fabric is usually better with a 3-inch hem to "weight" the hem and help it hang properly. To find the amount you need for the set of curtains:

Total length for each panel x Number of panels / 36 = Total fabric needed

Add on extra inches for tie backs, ruffles, fabric shrinkage, extra width, and other trimming preferences.

Calculate the Width

Many windows need more fullness than one length of fabric will achieve. A simple rule of thumb is that a curtain is one and a half to two times the width of the area it is meant to cover. A heavier fabric will provide fullness that a lightweight fabric can not. The lighter the weight of the fabric, the more fullness it will require.

For appearance and proper hanging, it is best to have at least a half-width of the original fabric when you need to add width to a panel. If you only want a couple of inches more than the original length of fabric will offer, cut away from the first length of fabric and add it on with the second length seamed to the first length of fabric.

Add more panel lengths to achieve the desired width. A 1-inch hem is usually sufficient for the sides of curtains.

Match the Prints

The selvage of many print fabrics has pattern repeat markings. These markings allow you to know when the pattern starts so that you can easily have every panel be the same. The amount of extra fabric to buy depends on how often the fabric repeats. There is no getting around buying extra to match a print.

Before You Make Your Final Purchase

• Will the fabric shrink? Always preshrink the fabric before you cut it.
• Did you double-check your calculations? Always measure twice to be positive before you cut.
• Do all the windows receive the same amount of sun or is one set of panels likely to fade more than the others? It may be worthwhile to buy enough fabric for an extra set of panels while.​

Solutions for Fabric Shortages

• Use a different fabric for hems and topper facings, seaming the fabric that will be on the back of the curtain at the folds. Using under-stitching helps the additional fabric stay to the backside of the curtain.
• Add borders of a contrasting print or solid fabric to add length and/or width.
• Use drapery weights to assist the way a curtain hangs.