Curtain Size Calculator - What Size Curtains Do I Need?
Use this free curtain size calculator to find the perfect curtain dimensions for your windows. Enter your window measurements, choose your curtain style and hanging height, and get instant recommendations for rod width, curtain length, and panel width.
How to Measure for Curtains
Getting the right curtain measurements ensures your window treatments look polished and professional. Proper measurement involves more than just the window opening itself; you need to consider the rod placement, desired fullness, and hanging style.
Measuring Window Width for Curtains
Start by measuring the width of your window frame from outside edge to outside edge. The curtain rod should extend 6 to 8 inches beyond each side of the window frame, which allows curtains to be pulled fully open without blocking the glass. This wider rod also makes the window appear larger. For a standard look, the total curtain fabric width should be 1.5 times the rod width. For a luxurious, heavily gathered look, use 2 times the rod width.
Hanging Height Tips
Where you mount your curtain rod dramatically affects the room's perceived proportions. Hanging curtains higher than the window frame makes the window and the room appear taller. The standard recommendation is to mount the rod 4 to 6 inches above the window frame. For maximum visual impact, mount the rod at or near the ceiling line. This is especially effective in rooms with standard 8-foot ceilings, where ceiling-mounted curtains create the illusion of much greater height.
Understanding Fullness Ratios
Fullness ratio refers to how much wider the curtain fabric is compared to the rod width. A 1.5x fullness ratio is the minimum for a decent gathered appearance and is suitable for casual or modern spaces. A 2x ratio provides rich, full folds and works well in formal rooms. A 2.5x or 3x ratio creates deep, dramatic pleats typically seen in formal drapery with pinch-pleat or goblet-pleat headings. Flat panel curtains use a 1x ratio for a clean, contemporary look.
Standard Curtain Sizes
Ready-made curtains come in standard lengths: 63 inches, 84 inches, 95 inches, and 108 inches. The 63-inch length works for sill-length treatments on standard windows. The 84-inch length is the most popular and suits most windows with rods mounted a few inches above the frame. The 95-inch length works well for floor-length curtains in rooms with 8-foot ceilings. The 108-inch length is ideal for rooms with higher ceilings or for creating a puddle effect.
Frequently Asked Questions
How wide should curtains be compared to the window?
The total curtain width should be 1.5 to 2 times the width of the curtain rod. The rod itself should extend 6 to 8 inches past each side of the window frame. So for a 48-inch window, the rod would be about 64 inches wide, and you would need 96 to 128 inches of total curtain fabric. Split between two panels, each panel should be 48 to 64 inches wide. A 1.5x ratio provides a standard look; 2x gives a more luxurious appearance.
How high should I hang curtains above the window?
Hang curtains 4 to 6 inches above the window frame for the best look. This is the most popular approach and visually elongates the window. For a more dramatic effect, hang the rod at ceiling height, which creates the illusion of taller windows and a grander room. At minimum, mount the rod at the top of the window frame. Never mount it below the frame top.
Should curtains touch the floor?
It depends on the style you want. Standard curtains hover about 1/2 inch above the floor for a clean, tailored look and easy cleaning. Floor-length curtains just barely kiss the floor for a more elegant appearance. Puddle curtains extend 2 to 3 inches onto the floor for a dramatic, romantic look best suited for formal spaces. For kitchens, bathrooms, or above radiators, sill-length curtains that end at or just below the window sill are the most practical choice.
What standard curtain length should I buy?
Ready-made curtains are available in 63-inch, 84-inch, 95-inch, and 108-inch lengths. Measure from the rod to your desired ending point and choose the closest standard length. The 84-inch length is the most versatile and works for most standard windows with rods mounted 4 inches above the frame. If you fall between sizes, choose the longer option as curtains can be hemmed but not extended.