Taking Measure

The first step to sewing your own curtains is measuring. Read my previous post first about preparing to make lined curtains.

This project is covered in three parts. This is part two.

Measure The Window Width:

This is the start of your preference decisions. Measuring width is the distance across the window horizontally. You will need to include the entire area to be covered with the finished curtain so include the casing and how far off to the sides you want your curtains to hang. I suggest you use a metal tape measure rather than a fabric measuring tape. The metal will make it easier for you to get accurate measurements.

First method: Measure the width from the outside edge of the window casing – side to side across the top of the window and a second measurement across the bottom side to side. (If there is a variance, take the wider measurement). You may also include the width at the sides where the open curtains will hang. This will depend on your rod placement and whether you want your curtain completely off to the side of the window when open. This is of course based on preference, your window location and how your window rod is installed.

Record this number as your window width OR

Second method: Measure the width of your curtain rod between the finials (decorative ends) of the rod. This measurement will likely be wider than measuring your actual window edges, but may be more accurate if your rod extend past your window casings a lot on the sides. You decide.

Record this number as your window width.

Measure The Window Length:

Measure from the rod where you will hang your curtains down to where you want the curtain to extend. For some windows this will be the bottom of the casing. For full length curtains, measure down to the floor leaving at least a 1/2 inch clearance so they don’t drag and collect all your dust :-). You should add an inch or so to this measurement for the fabric that will rise above the rod. I used about 3/4″. Remember this amount for when you place your grommets.

Record this number as your window length.

Calculate the Size to Cut Your Fabric

Main Fabric

Width: Window width x 1.5^* + 2 inches + 1 inch seam allowance (SA)
Length: Window length + 8 inches (for 4″ bottom hem^**) + 5 inches (for 4″ header with 1″ turn-down)

Lining

Width: window width x 1.5^* + 1 inch seam allowance
Length: window length

*The 1.5 multiplier is the amount of fullness you want for your curtains. For a fuller look, you can multiply by 2 or even 3 for sheers or pleated curtains. I use 1.5x here as that is most commonly used for curtains with grommets.

^** For a smaller bottom hem, decrease this size. Floor length drapes often have a 4 inch hem, so this would add 8 inches which is what I used here.

Note: If your fabric is wrinkly, especially the liner, you may want to iron first for accurate cuts.

Calculate the Amount of Fabric to Buy

To estimate the amount of fabric needed, you will use the final cut sizes you estimated above AND the width of the fabrics you have chosen to purchase.

Curtains are made in long vertical strips. Each strip or panel can only be as wide as the fabric you have. So the first step in measuring is to see how far across window each strip or panel of fabric will reach so we know how many panels will be needed.

To estimate this, first you need to decide on the amount of fullness you want in your curtain. Minimum is really about of 1.5 times the width to get nice ripples in your curtain, but fuller curtains will be 2 or 2.5 times the width of the window. You have to make a choice here but fuller isn’t always better, especially with grommets. Also, if you are getting an expensive fabric, this can really add to the cost. Sometimes I jiggle the numbers back and forth until I find a good balance between price and fullness.

Measuring the length of the window will tell us how long each panel has to be. Adding all the panel lengths end to end gives us the total length in inches you will need. Convert that to yards or metres and Bob’s your uncle!

So here is the formula written out.

Number of Panels you will need:

Width x 1.5* = X inches. X inches divided by width of fabric = Approx. No. of Panels

Window width multiplied by the *amount of fullness you want (usually 1.5). Divide this by width of fabric to figure how far across the width goes, i.e., the number of panels needed to cover your window side to side. Important: Always ROUND UP this result to whole number. Even if you need just about 2.1 panels you must estimate with 3. If you don’t, it won’t fit across! You could change your fullness amount to get it down to 2 panel for instance, but if not, you must round up to 3 panel.

So taking the number of panels you calculated, multiply that by the cut length you calculated earlier. This is how long each panel will be to cover your window.

No. of Panels x Length divided by 36 for yards or 39 for metres = Length to buy

Below is a cheat sheet to record your calculations. You can download it as a PDF.

Curtain Calculator pdf Download

Okay, next up we sew! – this is actually the easiest and fastest part!