Blackout Curtain Measurement
Blackout curtains only actually block light when they are wider than the window, hung higher than the frame, and long enough to kiss or pool on the floor. A panel ordered the exact same width as the glass leaves a visible strip of dawn light around the entire frame, which is the opposite of what you bought the curtains for. This tool takes the width and height of your window, adds proper overage for fullness, rod extension, and hem drop, then returns the total panel width and length you should order. Results assume a grommet or rod pocket style, two panels per window meeting in the middle, and a standard rod extension. If you plan to use a single panel across a wide window, double the recommended panel width. Floor pooling is optional and noted in the output.
Three tips before you buy
- Look for a triple weave or 100 percent blackout label. Room darkening fabric blocks only about 80 percent of light.
- Add a ceiling mounted rod instead of a frame mounted rod for the most dramatic blackout effect.
- Wash the panels on cold before hanging. Most blackout fabrics have a starch finish that softens after one cycle.
FAQ
Why so much extra width?
Blackout fabric only blocks light when it gathers in folds. A flat panel the same width as the window leaks light along the edges and looks slack.
Should the rod extend past the window?
Yes. Extending the rod six to twelve inches past each side of the frame lets the panel sit outside the glass when open and still cover the frame when closed.
How high should I hang the rod?
About four to six inches above the frame, or all the way to the ceiling for a taller room effect. Higher rods make windows look larger and block more top edge light.