🪟 Interactive Curtain Size Calculator
Enter your window dimensions and preferred hanging style below.
How to use the curtain calculator
- Measure the window: Measure the width and height of the glass or the outer window frame, whichever is larger. Enter both numbers and choose inches, centimetres, feet or metres.
- Choose the length style:
- Sill length ends right at the window sill and works well in kitchens and over radiators.
- Below sill (apron) falls about 15 cm (6 in) below the sill for a tailored look.
- Floor length hangs almost to the floor, and looks the most elegant in living rooms and bedrooms.
- Select fullness: Fullness is how much extra fabric is gathered into folds. 1.5x is light and modern, 2x is the standard choice and 2.5x gives a rich, heavy drape.
- Add the sill height for floor-length curtains: Measure from the floor to the window sill. The tool needs it to work out the finished drop.
- Press the button to see all the sizes together.
The formulas we use
- Rod length = window width + 30 cm (the rod extends 15 cm beyond each side of the window)
- Total curtain width = rod length × fullness
- Width of each panel (for a pair) = total curtain width ÷ 2
- Finished length (sill) = window height + 10 cm (the rod sits 10 cm above the window)
- Finished length (apron) = window height + 10 cm + 15 cm
- Finished length (floor) = floor-to-sill height + window height + 10 cm − 1 cm (a small gap so the hem clears the floor)
- Fabric to buy = number of fabric widths × (finished length + 25 cm for hems)
The number of fabric widths is the total curtain width divided by the width of the fabric roll, rounded up. Our calculator assumes a common 140 cm wide fabric roll. If your fabric is 280 cm wide, you will need about half the number of widths.
Worked example: floor-length curtains for a 120 cm window
Your window is 120 cm wide and 150 cm high, and its sill is 90 cm above the floor. You want floor-length curtains with standard 2x fullness.
| Step | Working | Result |
|---|---|---|
| Rod length | 120 + 30 | 150 cm |
| Total curtain width | 150 × 2 | 300 cm (150 cm per panel) |
| Finished length | 90 + 150 + 10 − 1 | 249 cm |
| Fabric widths | 300 ÷ 140 = 2.14, round up | 3 widths |
| Fabric to buy | 3 × (2.49 + 0.25) | about 8.2 m |
If you are buying ready-made curtains instead, look for panels around 150 cm wide and about 250 cm long. Standard ready-made drops are often 213 cm or 274 cm, so choose the nearest size and adjust the rod height slightly to make it work.
Why the rod should be wider and higher than the window
Mounting the rod exactly at the window edge forces the curtains to cover part of the glass even when they are open. Extending the rod 15 cm on each side lets the panels stack against the wall and leaves the whole window clear, so more daylight comes in. Placing the rod 10 cm above the frame (or even closer to the ceiling) draws the eye upward and makes the ceiling look taller.
Choosing fullness and fabric
Light, sheer fabrics such as voile or linen blends look best with 2 to 2.5x fullness, because thin material needs plenty of folds to look rich. Heavier fabrics like velvet or thick cotton are often fine at 1.5 to 2x, since the weight already creates soft, deep folds. Pleated headings, such as pinch pleat or wave, have specific fullness ratios. Check with your tailor before you order.
Tips for a professional finish
- Measure twice: Windows are rarely perfectly square. Measure at the top, middle and bottom, and use the largest number.
- Check for obstacles: Radiators, window handles and furniture may affect the length you can use.
- Hang before hemming: If you are stitching yourself, hang the curtains for a day before setting the final hem so the fabric can drop.
- Use a pair, not a single panel for windows wider than about 120 cm. A pair looks balanced and is easier to open and close.
- Use lining: A lining protects the fabric from sun fading, improves the drape and helps block light and noise.
- Keep the hem consistent: Floor-length curtains should hang 1 to 2 cm above the floor, or gently kiss it for a luxurious puddled look.
Frequently asked questions
What size curtains do I need for a 60 inch window?
A 60 inch window needs a rod of about 72 inches with standard 2x fullness, meaning a total curtain width of about 144 inches. Buy two panels of at least 72 inches each.
How far should curtains hang from the floor?
Aim for about 1 to 2 cm above the floor for a neat look. Some people prefer them to touch the floor lightly, and a "break" or "puddle" adds a dramatic, relaxed style.
How high above the window should I hang the rod?
Between 10 and 15 cm above the window frame is common. In a room with a low ceiling, hang it as high as possible to create height.
What is the best curtain fullness?
For most homes 2x is the best compromise between cost and appearance. Use 1.5x for a clean, minimal look and 2.5x for a luxurious feel.
How much fabric do I need for two panels?
Enter your window measurements above and the calculator will show the meters of 140 cm wide fabric you need for both panels together, including hems.
Can I use this for a sliding door or a wide bay?
Yes. Enter the total width of the opening. For very wide spaces, split the curtains into several panels and treat each section separately, so the fabric moves smoothly along the track.
Continue planning your room
After you have picked the curtains, choose a rug that suits the space with our Rug Size Guide, and pick colours that match using our 60-30-10 Colour Palette Generator.