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About this tool
Find curtain colours that complement wall paint and upholstery, with LRV gaps, hue distance and fade risk for each.
The Curtain Colour Matcher takes the hex value of your wall paint and your main upholstery and returns eight curtain colours, each scored by its Light Reflectance Value gap from the wall — the number that decides whether the window disappears, sits quietly, or becomes the focal point of the room. LRV is the CIE Y value as a percentage, the same figure printed on a paint chip and calculated here with the WCAG relative luminance formula. It also measures the hue distance between the wall and the sofa on the colour wheel, because two colours already sitting 45 to 100 degrees apart leave a curtain far less room to manoeuvre than a tonal pairing does.
Open Curtain Colour Matcher on AltFTool — it loads instantly in your browser.
Enter the wall colour hex and the upholstery colour hex, or set them with the two colour pickers.
Say what the curtains should do, disappear, frame the window quietly or be a feature, and set the sun on this window.
Read the eight suggested swatches with their LRV gap and fade risk in strong sun, then press Copy result.
Each option shows how far it sits from the wall in LRV, so you know in advance whether the window recedes or dominates.
Hue distance between the two is measured first, and the suggestions change depending on how much room that leaves.
Dark saturated fabric at a south or west window is called out before you order twelve metres of it.
Match the wall when you want the room to feel larger, and match the sofa when you want the two big fabric areas to read as a set. Keeping the curtain within about 10 LRV points of the wall makes the window disappear into the wall plane, while pulling the sofa hue to the window ties the scheme together but makes the window a visible element.
Either works — what matters is the size of the gap, not the direction. Under roughly 10 LRV points the curtain merges with the wall, 10 to 30 points frames the window quietly, and more than 30 points makes it the focal point of the room; on a wall that is already dark, going lighter is the only option that registers.
Yes, and noticeably faster in appearance than pale ones. UV breaks down dye regardless of colour, but the same absolute pigment loss is a much larger proportional change in a dark, heavily saturated fabric, so the leading edge of a deep curtain at a south or west window can show visible lightening within a few summers. A lining, or a solution-dyed or UV-stabilised fabric, slows it considerably.
One within about 10 LRV points of the wall, in the same hue family, hung floor to ceiling and wide enough that the stack sits on the wall rather than the glass. Continuous tone across the wall and window removes the visual break that makes a room read as a series of small panels.