These are not at all light blocking, they are very thin with no lining. They darken the room as much as hanging any kind of light linen fabric over a window would darken it. I love the color and the pattern. In order to make these look plush you need to order 3 times the window width in panels (you should always order at least 2 times the width when buying any curtains). They do not hit the floor evenly even though they are hung evenly. I'm wondering if they will hit the floor evenly after being steamed. Fingers crossed.