Curtain Calculator
Calculate fabric yardage, panel dimensions, and rod width for custom curtains and window treatments.
About this calculator
This calculator turns four inputs — window width and height, mount type, fullness, and panel count — into the concrete numbers a curtain workroom or DIY sewer actually needs: rod width, finished panel dimensions, stack-back, and fabric yardage. Mount type changes the geometry: an inside mount uses the window's own width for the rod, while an outside mount adds 12 inches total (6 inches of overhang per side) so the panels can fully clear the glass when open. Panel height follows the same split — inside mount trims a half-inch off window height, outside mount adds 10 inches to account for hanging 4 inches above the frame and running to roughly 6 inches off the floor — then both get 8 inches added for the top header/rod pocket and bottom hem.
Panel width comes from the rod width times your fullness multiplier (1.5 for a casual, loosely gathered look up to 3.0 for luxury pleating), split across the panel count, plus 3 inches per panel for side hems. For fabric yardage, the calculator runs two methods — a bolt-cut approach based on how many panels fit across a standard 54-inch-wide bolt, and a simpler total-area method with a 15% waste allowance — and reports whichever comes out larger, so you're less likely to come up short. Because the floor-clearance and above-frame assumptions are generic defaults, measure your actual desired drop if precision matters, and remember that fullness has an outsized effect on total yardage.
Inputs
Results
Panel Width (each)
63 in
≈ 11 smartphones
Panel Height (each)
78 in
≈ 13 smartphones
How to Use This Calculator
- Enter Window Width, Window Height, and Mount Type.
- Set Fullness Multiplier and Number of Panels.
- Review Panel Width (each) (in) and Panel Height (each) (in).
- Use Total Fabric Needed (yards) and Curtain Rod Width to inform your decision.
How the result changes with Fullness Multiplier
| Fullness Multiplier | Panel Width (each) | Panel Height (each) |
|---|---|---|
| 1 | 33 in | 78 in |
| 1.5 | 48 in | 78 in |
| 3 | 93 in | 78 in |
What each input means
- Window Width
- Inside width of the window opening in inches.
- Window Height
- Inside height of the window opening in inches.
- Mount Type
- How the curtain rod mounts relative to the window frame.
- Fullness Multiplier
- Fabric fullness: 1.5 = casual, 2.0 = standard, 2.5–3.0 = luxury pleated.
- Number of Panels
- Panel count — typically 2 for a split draw, 1 for a single panel.
What each result means
- Panel Width (each)
- Finished width for each panel including side hems.
- Panel Height (each)
- Finished height including top header and bottom hem allowances.
- Total Fabric Needed
- Linear yards of 54-inch-wide fabric required.
- Curtain Rod Width
- Recommended rod width based on mount type.
- Stack-Back (each side)
- Space panels occupy when fully open (each side).
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersWindow Width = 48, Window Height = 60, Mount Type = 1, Fullness Multiplier = 2 = 5 input(s) provided
- Calculate Panel WidthPanel Width63 = 63
- Calculate Panel HeightPanel Height78 = 78
- Calculate Total Fabric Needed5.81 = 5.81
- Calculate Curtain Rod WidthCurtain Rod Width60 = 60
Engine last updated . Checked against 1 independently-derived test — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does an outside mount add exactly 12 inches to the rod width?
The calculator adds 6 inches of overhang on each side of the window frame so the panels can stack fully off the glass instead of blocking part of it when open. That 6-plus-6 becomes rodWidth = windowWidth + 12 for any outside mount, while an inside mount just uses the window's own width since the rod sits inside the frame with no overhang to add.
How much does raising the fullness multiplier actually change my fabric needs?
Fullness multiplies the rod width directly to get the total gathered width (rodWidth × fullness), which then feeds panel width and, from there, total fabric yardage. Going from a casual 1.5 to a luxury 3.0 roughly doubles the gathered width and pushes yardage up by nearly the same factor, so fullness has more leverage over your fabric budget than almost any other input.
Why does the calculator show two fabric yardage methods and only report one number?
Internally it computes yardage two ways — a bolt-cut method that figures out how many panels fit across a 54-inch-wide bolt and how many cuts that requires, and a simpler total-area method that adds a flat 15% waste allowance. It then reports whichever of the two comes out larger, so a quirk in one method (like panels not dividing evenly across the bolt width) can't leave you short on fabric.
What does the stack-back number tell me that panel width doesn't?
Stack-back estimates how much wall space each panel occupies to the side of the window when fully drawn open, calculated as 33% of the rod width divided across your panel count. It matters for planning where furniture or trim can go near the window — a wide rod with few panels stacks back further per panel than the same rod split into more panels.
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