The correct proportions for custom drapes and curtains

When you begin to make custom drapes and curtains, how do you know you'll be successful? Will you just 'wing' it, and hope for the best? Or are there some guidelines you can follow? And what exactly is involved in the whole process?

Well, to put it simply, all you have to do is to decide where all the bits and pieces are going to go.

Briefly, how far the pole or track will go either side of your window, and if you have swags, a cornice or valance, how deep they will be. Plus a few other decisions.

Height of cornice box above window

cornice box above windowIllustration showing position of cornice box above window

The bottom of the treatment should just cover the top of the window frame by a couple of inches.


So the treatment frames the window but doesn't cut out any daylight.

So calculate how deep the top treatment should be, then fix your cornice board accordingly.

The narrowest section of the cornice box should just cover the window as shown in the illustration. When the curtains are pulled back they and the cornice are positioned just over the window. This lets in the maximum amount of light while still 'dressing' the window.

Make the depth of the top treatment approximately one fifth of the finished length of the drapes.

You'll also use a board for your custom drapes and curtains if you want to use a valance. Yes, I know you can buy 'valance kits' which include a curtain track and a track to support the valance. And they're fine for light and casual treatments. But there are reasons why professionals use a board for their drapery.

You want your window treatment to look good, right?

How far up should a pole go?

The pole should be placed so the top of the curtains are above the top of the window by a couple of inches. When the curtains are pulled together they completely cover the frame.

Poles and tracks are ideal if you don't have much space above your window. I normally fit them at least 3" (8cms) up, and sometimes more depending on the situation. My rule of thumb is to fit the pole one third of the way up from the top of the window. If the space is large (you could fit a cornice but you prefer a pole) then fit the pole about 4" or 5" up.

How long should the pole or track be?

This depends on the stack back (the wall area the drapes hang against when they are fully open). This stack back size will vary depending on a number of factors.

  • The number of widths in the drapes.
  • The thickness of fabric, lining and interlining (thin fabric and interlining will stack closer together than thick ones).
  • The fullness of the drapes.
  • Whether the tracks are corded or not (corded tracks need a bit more space).

An approximate guide is to add 15% of the window width on either side.

How long should the curtains be?

valance above windowAs with a cornice box, a valance should be positioned so it and the curtains frame the window.

I prefer floor length for custom drapes and curtains every time, but I accept that this isn't always ideal, or even possible. Floor length drapes look more elegant and imposing than sill length ones for drapery window coverings. You can have them just off the floor, just touching, or falling onto it in folds - known as 'puddling'.

For a really majestic finish you can have your drapery tied back with your own made-up tiebacks, or with sumptuous double tassel ones.

When you have to have sill length drapery, then make it with the same care and attention to detail.

If your drapes are going to hang inside the frame, then have them finish just above the sill. If they will be fitted outside, then make them to hang 4" to 6" below the sill, depending on the window height.

grand roomProportions are important no matter how large or small your room, or your style of furnishing.

Practicing proportions for custom drapes and curtains

Get some old sheets or any old fabric. Bunch the fabric and pin it up where the drapes are going to hang. Use fabric, paper or card and make a replica valance, cornice or swags. Pin these up as well. This will give you a good idea of how your custom drapes and curtains will look.

It's best to use very plain fabric for this, which is why old sheets are ideal. You're not looking to see the effect of pattern or color, but the proportions. So ask yourself:

  • Do the various parts of the treatment balance with one another? Is the valance too shallow, or does it look too heavy with the curtains?
  • Is the overall scheme in proportion with the window and the rest of the room?

By using old sheets, paper and card you can easily adjust your scheme to get it right.


The proportions of your custom drapes and curtains are tied to window size, shape and position. It's worth spending as much time as necessary on this stage so you get your design just right.

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