Curtain Rod Length Calculator
Enter the window width and how far past each side you want the rod to reach to find the rod length, a range to shop within, and which adjustable rods cover it.
Curtain Rod Length Calculator calculates in your browser.
Why the rod should be wider than the window
A curtain rod that stops at the window frame leaves open curtains hanging over the glass, blocking light and making the window look smaller. Running the rod past each side gives the curtains somewhere to stack when they are open, and makes the window look wider than it is.
How far is a design choice. This calculator adds the extension you choose to both sides of the window, shows the range of rod lengths for the least and most extension you would accept, and checks which common adjustable rods reach that length — or your own rod’s range, if you enter it.
How to use the Curtain Rod Length Calculator
- Choose inches, feet, centimeters, or meters.
- Measure the window from the outside edge of the frame or trim on one side to the other.
- Enter how far past each side you want the rod to go, and the least and most you would accept.
- Add the finial length if your rod has decorative ends, to see the overall width.
- Enter your adjustable rod’s range, if you already have one, to check it reaches.
How the calculation works
Rod length = window width + 2 × extension per side
Range = window + 2 × least extension to window + 2 × most extension
Overall width with finials = rod length + 2 × finial
A 48 in window with the rod 8 in past each side needs a 64 in rod, which a common 48–84 in adjustable rod reaches. Use that 64 in as the rod width in the Curtain Width Calculator to size the curtains to match.
| Window | Past each side | Rod length | Range |
|---|---|---|---|
| 48 in | 8 in (range 4–12 in) | 64 in | 56 in to 72 in |
| 36 in | 4 in (range 4–12 in) | 44 in | 44 in to 60 in |
| 72 in | 12 in (range 4–12 in) | 96 in | 80 in to 96 in |
| 120 cm | 20 cm (range 10–30 cm) | 160 cm | 140 cm to 180 cm |
Calculated on your device
- The length is worked out in your browser as you type; nothing is sent to a server.
- Your measurements and results are not sent to Looty Tools or stored.
- The calculator area, including the drawing, is masked from session-recording analytics.
Limitations
- Extensions are design guidance, not requirements; walls, corners, and nearby windows may limit how far you can go.
- Adjustable rod ranges are typical; check the packaging for your rod’s actual range.
- It doesn’t size brackets or say when a center support is needed — longer rods usually need one; follow the rod’s instructions.
- Bay, corner, and arched windows aren’t modeled.
- Widths up to 100 ft (30.48 m).
Related calculators
- Curtain Width CalculatorEstimate how wide curtains should be for a window.
- Curtain Panel Count CalculatorEstimate how many curtain panels a window needs.
- Length ConverterConvert inches, feet, meters, and other lengths.
Guides
- How Wide Curtains Should BeHow wide curtains need to be for your window or rod: the fullness formula, returns and overlap, and worked examples in inches and centimeters.
- How Long a Curtain Rod Should BeFind curtain rod length from the window width and extension each side, with examples, a range to shop within, and where finials come in.
- Curtain Rod ExtensionWhy curtain rods extend past the window, common extensions from a few inches to a foot, how stack-back sets the minimum, and what to do when space is tight.
- Adjustable Rod SizesCommon adjustable curtain rod ranges in inches and centimeters, how to choose the right range, when rods need a center bracket, and custom options.
Curtain Rod Length Calculator FAQ
- How long should a curtain rod be?
- The window width plus the extension on both sides. A 48 in window with the rod 8 in past each side needs a 64 in rod; anywhere from 4 to 12 in each side gives 56 to 72 in.
- How far should a curtain rod extend past the window?
- A few inches is a practical minimum so open curtains don’t cover the glass; 8–12 in each side is common for full-length curtains and makes a window look wider. Thick or lined curtains stack wider, so they may need more. It is a design choice, not a rule.
- Which adjustable rod should I buy?
- One whose range includes your length, ideally not at its very end. A 64 in rod falls in the common 48–84 in range. Ranges vary by brand, so the calculator lets you enter your own.
- Do finials count in the rod length?
- Not in the rod’s length, but they need wall space. With 3 in finials on a 64 in rod, the whole thing is 70 in wide.
- What do I do with the rod length next?
- Enter it as the rod width in the Curtain Width Calculator to find how much curtain covers it, then count panels with the Curtain Panel Count Calculator. All three use the same math.
- Are the measurements I enter sent anywhere?
- No. The check runs in your browser as you type. Your measurements and results are not sent to Looty Tools or stored, and the calculator area is masked from session-recording analytics. Refreshing the page clears it.
