This curtain does a great job blocking the sun out. It is 100% blackout. Other blackout curtains I've bought have had a few tiny holes in them, but this curtain didn't have any tiny holes that I could see. My curtain rod goes a little too far out, so it causes light to come out from the sides. If my curtain rod didn't stick out, I wouldn't see light coming from the sides. I even looked at the window where this curtain is outside in the dark, I couldn't see any inside light from the house coming through it (except the sides). My favorite thing about these curtains is that they are also thermal. It helps keep energy costs lower since they block the cold air in the Winter and prevent the sun from heating the house through the windows in the summer. I have not machine-washed them yet, but I am so glad that I have the option to wash them if I needed.