Curtain Size Calculator
Enter the window width and height to get curtain length, panel width, rod length and fabric amount.
Curtain length
Fullness ratio
Window height (cm)
Window width (cm)
Number of panels
Curtain Size Calculator: Fabric Amount and Rod Length
The most common mistakes when buying or ordering curtains are measuring wrong and forgetting the fullness ratio. Enter your window dimensions and curtain style, and the calculator shows panel width, total curtain length, rod length and fabric amount.
Curtain Length Standards
To the floor: the bottom edge stops 1–2 cm above the floor, the classic look. To the sill: ends 1–2 cm above the sill, practical for kitchens and bathrooms. Floating: leaves a 5–15 cm gap above the floor and looks more modern. Puddle: part of the fabric rests on the floor, giving a heavier, more formal look; the calculator's extra-long option adds 30 cm for this.
The fabric amount does not include cutting allowance or pattern repeat. For patterned fabric, add one pattern repeat per panel. If you use lining, add the same amount of lining fabric.
Common Mistakes When Taking Curtain Measurements
Common mistakes are measuring the wall instead of the window frame, not leaving enough length for the curtain to hang, and ignoring the rail width. Measure so the curtains overlap the rail by at least 15 cm on each side. This keeps light from leaking in at the edges and makes the window look fully covered.
Key Considerations When Choosing Curtain Fabric
Thick blackout fabrics block more light and sound. Thin voile and sheer fabrics let light through and soften it. Heavier fabrics need a stronger rail and fixings.
Fullness Ratio and Fabric Weight Relationship
A higher fullness ratio uses more fabric, so the fabric's weight affects both the cost and the load on the rail. Lightweight fabric at 2.5× gives full, deep folds. Heavy velvet or tapestry forms enough folds at 1.5×. Check the fabric weight in grams per square metre when you choose.
Using Lining for Curtains and Its Benefits
Lining makes curtains last longer and adds heat and sound insulation. It also blocks morning light, which helps you sleep. Cotton and polyester are the most common lining fabrics. If you use lining, add the same amount of lining fabric as curtain fabric and cut both layers to the same width and length.
Measurement Guide for Different Window Types
Arched, corner and composite windows are measured differently from standard rectangles. For an arched window, take the curtain width from the horizontal span rather than the length of the arc, and measure the length from the floor to where the arch begins. For composite windows, measure each section separately and mount them all on one rail. Attic windows look and work better with rail systems made for them.