Calculate curtain rod length, window width, or overhang by entering any two values and choosing inches, feet, centimeters, or meters.
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Curtain Rod Length Formula
The basic curtain rod length formula adds the window width to the overhang on both sides of the window.
- CRL = curtain rod length
- WW = window width
- O = desired overhang on each side
If you already know the rod length and want to find the overhang on each side, use:
If you know the rod length and the overhang, you can calculate the window width with:
The calculator uses inches as the base unit for the calculation. If you enter feet, centimeters, or meters, the value is converted to inches first, the formula is applied, and the answer is converted back to the unit you selected for the missing value.
- To calculate curtain rod length: enter the window width and the desired overhang per side.
- To calculate overhang: enter the window width and the full curtain rod length.
- To calculate window width: enter the curtain rod length and the overhang per side.
Common Curtain Rod Overhang Guidelines
Overhang is the extra rod length beyond the window frame on each side. A larger overhang lets curtains stack farther away from the glass when open.
| Use case | Typical overhang each side | Effect |
|---|---|---|
| Minimum coverage | 3 to 4 in | Covers the window edge with limited curtain stack space. |
| Standard installation | 4 to 6 in | Works for many rooms and allows better light clearance. |
| Fuller look or wide panels | 6 to 12 in | Lets curtains stack outside the window for a wider appearance. |
Window Width to Rod Length Examples
| Window width | Overhang each side | Rod length |
|---|---|---|
| 36 in | 4 in | 44 in |
| 48 in | 6 in | 60 in |
| 60 in | 8 in | 76 in |
Example Problems
Example 1: Calculate curtain rod length
You have a window that is 50 inches wide, and you want the rod to extend 6 inches past the window on each side.
The curtain rod should be 62 inches long.
Example 2: Calculate overhang
You have a 72-inch curtain rod and a 60-inch window. To find the overhang on each side:
The rod extends 6 inches past the window on each side.
FAQs
How far should a curtain rod extend past the window?
A common choice is 4 to 6 inches past the window on each side. Use 3 to 4 inches if space is tight. Use 6 to 12 inches if you want the curtains to open more fully without blocking the glass.
Is overhang measured on one side or both sides?
In this calculator, overhang is measured on each side. If you enter 6 inches for overhang, the formula adds 12 inches total to the window width.
What if the calculated rod length is not a standard size?
Choose the next available adjustable rod size that includes your calculated length. For example, if the result is 62 inches, an adjustable rod with a range such as 48 to 84 inches would fit that measurement.
