Curtains are a functional design element that provides privacy, warmth and style to any room of your home. One of the most important aspects of purchasing ready made curtains, or other window treatments, is to understand how to measure the window correctly. In general window treatments are measured width by length and you will see them sized this way throughout the Port and Bay website. Even valances, that take up only a portion of the window frame, are measured width by length.

We will reference curtains throughout this post but the same measurements apply to: Tier Curtains, Sheers, Grommets, Tab Curtains, Valances amongst others.

Curtain Length

The first step is determining how the curtains will sit either on the wall above the window frame (outside mounting) or within the window frame (inside mounting). This is typically a style decision but will change the measurements we take.

Outside Mounting:
Typical bracket placement for these types of window coverings are 3” to each side of the window frame and 3” to 6” above the top edge of the window frame. Outside curtain mounting is the most common style and provides full coverage of the window for blocking out light or privacy. This style also creates the illusion of a larger window size.

Inside Mounting:
Providing a modern look for certain curtain styles, such as valances, can be inside-mounted using utility or spring pressure rods. For this style the distance from the desired mounting point to the window sill will be the most important measurement.

Curtain Width (Fullness)

With regards to curtains we often talk about fullness when determining the width or more importantly how many panels or packages of a particular product you will need. To calculate fullness, you take the width of the window and multiply it by the desired fullness. The fullness of your curtains will vary based on your personal preference. Generally speaking, fullness is calculated by taking the width of the window and multiplying it by the corresponding fullness below:

Grommet style
1.5 to 2 times fullness

Curtains shirred/gathered onto rod pockets
2 to 3 times fullness

Tab style
1.5 to 2 times fullness

Sheers and lace curtains
3 times fullness (some customers prefer less fullness with certain lace patterns in order to show the pattern better).

Helpful Tips

Using floor to ceiling length curtains makes the room appear larger.

If your room has many different length and width windows, covering them with curtains that are all the same length will make the room appear larger.

To improve energy efficiency, choose lined products that can be completely closed in summer or winter. Be sure to keep their length 6 inches or more away from electric baseboards.