Curtain Size Converter

Curtains need to be wider than the window to look full and pleated.

Fullness ratio determines how gathered the curtains look:

• 1.5x = flat/casual look (minimal gathering)
• 2x = standard fullness (most common)
• 2.5x = full/luxurious look
• 3x = very full/formal (pinch pleats)

Curtain width formula:

• Total curtain width = window width × fullness ratio

Rod length guidelines:

• Rod should extend 8–12 inches (20–30 cm) beyond each side of the window
• This makes the window appear larger and allows curtains to stack off the glass

Example (metric):

• Window width: 150 cm
• Fullness: 2x
• Total curtain fabric: 150 × 2 = 300 cm
• Rod length: 150 + 20 + 20 = 190 cm

Example (imperial):

• Window width: 60 inches
• Fullness: 2x
• Total curtain fabric: 60 × 2 = 120 inches
• Rod length: 60 + 10 + 10 = 80 inches

For two panels, divide the total width by 2.

The most common curtain mistake is buying panels the same width as the window, which leaves them looking skimpy and stretched flat when closed. Fullness is the whole point: even a casual look wants 1.5 times the width to cover, and 2x is what reads as proper curtains. And you measure fullness against the rod, not the glass, because the rod runs wider than the window. Buy for the rod length times your fullness ratio, then split that across your panel count.

Length is the other decision, and it changes the whole feel of a room. Curtains ending at the sill look casual and work well over a radiator or a counter. Dropping to just below the sill is a safe everyday choice. Floor-length, with the hem just kissing the floor, looks the most finished, while letting fabric “puddle” an inch or two on the floor reads as formal and a touch dramatic. Whatever you pick, add hem and header allowance before cutting, usually around 15 to 25 cm in total, and remember that a bold pattern needs extra length so you can match the repeat between panels.