Curtain Size Calculator
Enter window width and height to instantly calculate curtain length, panel width, rod length and fabric amount.
Curtain length style
Fabric fullness
Window height (cm)
Window width (cm)
Number of panels
Curtain Size Calculator: Fabric Amount and Rod Length
When buying or having curtains made, the most common mistake is taking the wrong measurement or not accounting for the fullness ratio. This calculator takes your window dimensions and curtain style to instantly compute panel width, total curtain length, rod length and fabric amount.
Curtain Length Standards
To the floor: Bottom edge ends 1–2 cm from the floor; elegant and classic look. To the sill: Ends 1–2 cm above the sill; practical for kitchens and bathrooms. Floating: 5–15 cm gap from the floor; modern, dramatic effect. Puddle: 5–15 cm trailing on the floor; theatrical, luxurious feel.
Fabric calculation does not include cutting allowance or pattern repeat. For patterned fabric, add one pattern repeat per panel. If using lining, add the same quantity of lining fabric.
Common Mistakes When Taking Curtain Measurements
Common mistakes include measuring the wall instead of the window frame, failing to allow enough length for drape, and ignoring rail width. Curtains should be measured to overlap the rail by at least fifteen centimetres on each side; this is critical both for visual completeness and for preventing light gaps.
Key Considerations When Choosing Curtain Fabric
Fabric choice directly affects both the aesthetic and functional performance of curtains. Thick, blackout fabrics block light and sound more effectively; thin voile and sheer fabrics provide a soft light filter through their translucency. When considering fabric weight, it is important to remember that heavier fabrics require stronger rails and fixings.
Fullness Ratio and Fabric Weight Relationship
Because a higher fullness ratio uses more fabric, the weight of the chosen fabric directly affects cost and rail load. Applying a high fullness ratio (2.5×) with lightweight fabric creates a visually rich appearance, while a 1.5× fullness ratio is sufficient to create elegant folds with heavy velvet or tapestry. Checking fabric weight in grams per square metre during selection is helpful.
Using Lining for Curtains and Its Benefits
Lining extends the curtain's life, improves heat and sound insulation, and enhances sleep quality by blocking morning light. Cotton or polyester lining fabrics are the most common options. If lining is used, lining fabric equivalent to the curtain fabric quantity should be added to the calculation, and both layers should be cut to the same width and length.
Measurement Guide for Different Window Types
Windows other than standard rectangles — arched, corner or composite — require different measurement techniques. For arched windows, curtain width is measured from the horizontal span, not the arc length; length is calculated from the floor to where the arch begins. For composite windows each section is measured separately and mounted on a shared rail. For attic windows, using specialised rail systems improves both aesthetics and functionality.