Enter the window width and desired overhang into the calculator to determine the curtain rod length. This calculator can also evaluate any of the variables given the others are known.

Curtain Rod Length Formula

The following formula is used to calculate the length of a curtain rod.

CR = W + 2 * O


  • CR is the curtain rod length W is the window width O is the desired overhang on each side of the window

To calculate the curtain rod length, add the window width to twice the desired overhang on each side of the window. This will ensure that the curtain rod is long enough to cover the window and provide the desired amount of overhang on each side.

What is a Curtain Rod Length?

A curtain rod length refers to the measurement of the rod from one end to the other. This length determines how wide a window or space the rod can cover. It is important to choose a rod that is longer than the width of your window to allow for the curtains to be fully opened without obstructing the window. The length of the curtain rod can also affect the overall look and feel of the window treatment, with longer rods often creating a more dramatic or luxurious effect.

How to Calculate Curtain Rod Length?

The following steps outline how to calculate the Curtain Rod Length.

  1. First, determine the window width (W).
  2. Next, determine the desired overhang on each side of the window (O).
  3. Next, gather the formula from above = CR = W + 2 * O.
  4. Finally, calculate the Curtain Rod Length (CR).
  5. After inserting the variables and calculating the result, check your answer with a measuring tape.

Example Problem:

Use the following variables as an example problem to test your knowledge.

window width (W) = 60 inches

desired overhang on each side of the window (O) = 6 inches