Windows and decor
Curtain Panel Calculator
Estimate total curtain panel width, width per panel, rod width, and finished length from simple window measurements.
Curtain panel estimate results
- Rod width
- 72 in
- Total panel width
- 144 in
- Width per panel
- 72 in
- Finished length
- 84 in
- Metric per panel
- 182.88 cm
- Fullness
- standard gathered look
Saves in this browser only. Do not save sensitive personal or safety-critical project details.
Planning checklist
- Width per panel: 72 in
- Finished length: 84 in
- Check product width per panel or per pair.
Before buying, check
- Whether the listing width is per panel, per pair, or for the full set.
- Header style, rod pocket size, clip rings, and hardware weight limits.
- Finished length after the rod height, sill, apron, or floor target is measured.
This estimate is usually enough to compare curtain panel sizes. It is not enough for child-safety hardware, structural mounting surfaces, ceiling mounts, or professional design decisions.
Prefilled values are editable planning examples. Use the product label, package coverage, installer instructions, and your measured layout when they differ from the example default.
How this curtain calculator works
Curtain fullness is based on the planned rod width, not only the glass width. This tool adds side extension to both sides of the window, multiplies by fullness, then divides by panel count so you can compare product listings more clearly.
Curtain panel formula
Rod width = Window width + side extension x 2
Total panel width = Rod width x fullness ratio
Width per panel = Total panel width / panel count
Example calculation
A 60 in window with 6 in side extension on both sides has a planned rod width of 72 in. With 2x fullness and two panels, the curtains together need about 144 in of total width, or about 72 in per panel.
Common curtain measuring mistakes
- Buying based only on the glass width instead of the rod width.
- Confusing width per panel with width per pair.
- Choosing length before measuring the planned mount position.
- Ignoring header style, rod pocket size, or hardware limits.
Curtain calculator FAQ
How wide should curtain panels be?
Start with the planned rod width, multiply by fullness, then divide by the number of panels. Check whether the product lists width per panel or per pair.
What curtain fullness should I use?
A 1x ratio is flat, about 1.5x to 2x is a common gathered look, and higher ratios create a fuller decorative look.
Why does this calculator ask for finished length directly?
Finished length depends on rod height, sill or floor target, hardware, header style, and room layout. Entering the target length directly avoids guessing installation details.
Can this decide mounting hardware?
No. Hardware limits, mounting surface, child-safety requirements, and installation conditions should be checked with product instructions or qualified help.
Related calculators and guides
Calculation transparency
Method & Sources
This section documents the calculation boundary, arithmetic, rounding, and editable planning presets used by the Curtain Panel Calculator.
What it calculates
- Calculates a planning rod width by adding the chosen side extension to both sides of the measured window opening.
- Calculates the combined finished width of all curtain panels from rod width and the selected fullness ratio.
- Divides that combined width evenly across the selected panel count and shows width per panel in inches and centimeters.
- Carries the entered finished length through to the result and converts it between inches and centimeters for product comparison.
What it does not calculate
- It does not choose rod height, bracket position, mounting hardware, anchors, or load capacity for the wall and curtain weight.
- It does not add fabric for side hems, header construction, bottom hems, shrinkage, pattern repeat, motif placement, or sewing seams.
- It does not estimate stack-back space when curtains are open or verify clearance from floors, sills, radiators, vents, furniture, or doors.
- It does not determine child-safety hardware, fire requirements, motorized-track requirements, or whether the mounting surface is suitable.
Formula
- Rod width = window opening width + 2 x side extension.
- Combined panel width = rod width x fullness ratio.
- Width per panel = combined panel width / number of panels.
- Finished length is entered directly because mount height and the intended sill, apron, floor, or puddled endpoint are project decisions rather than values inferred from window width.
Rounding rules
- Unit conversion and width arithmetic are completed before lengths are displayed to two decimals. Panel count must be a whole number from 1 through 8.
- The calculator does not round width up to a commercial panel size; compare the required width per panel with the exact product listing and choose a combination that meets or exceeds the plan.
Why the defaults are planning presets
- The 60 in window, 84 in finished length, 6 in extension on each side, 2x fullness, and two-panel setup are editable planning presets, not universal curtain rules.
- The fullness labels are descriptive planning bands: below 1.5x is minimal gather, 1.5x to below 2.25x is a standard gathered look, 2.25x to below 3x is fuller, and 3x or more is very full. Fabric and header style can change the appearance.
- Product-listed width may describe one panel or a pair. The calculator assumes the entered panel count contains equal-width panels, so verify the packaging convention before buying.
Sources to check
- Measurement Assumptions & Unit Conversion HomeMeasureKit's shared policy for units, precision, waste factors, package rounding, and estimate limits.
- Curtain Measurement Guide Field-measurement sequence for the opening, rod span, finished length, fullness, and panel labels.
- Selected curtain and hardware specifications Primary project sources for finished panel width, panel count per package, header type, care, rod diameter, bracket spacing, and load limits.