This is definitely NOT a Blackout curtain. I recently moved and ended up buying 3 sets of blackout curtains for my windows, each from a different brand. This was probably the worst of the three regarding light blocking capabilities. I bought three of these panels to cover a 74” wide window. I probably should have gone with 4, and that’s on me, but even with if I had I’m not convinced it would have made me consider it “blackout”. However, I was more concerned with their thermal capabilities to keep heat out during the summer and in during the winter. It does seem to make a difference, though not a drastic one.