These curtains blackout 100% of the sunlight coming in through our sons' bedroom window. Their window faces east, so the early summer sunshine tends to wake them up earlier in the morning. And summer bedtime tends to be difficult given the longer days and the sun setting late. The curtains block out all of the light coming into their bedroom and helps us maintain normal schedules for our boys. The charcoal color looks great against their gray walls and I was surprised to notice the fabric is not as stiff and rigid as other types of blackout curtains we have tried.