I used to wake up freezing even with my curtains shut. I kept assuming the curtains were doing their job. They weren't.
Not all curtains block cold the same way, and that difference matters a lot in winter.
Do blackout curtains keep cold out? Yes, but only to a point.
In this article, I'll show you how they work, where they fall short, and what actually makes them effective.
I'll also help you spot the small mistakes that kill their performance. If your room feels cold no matter what you try, the problem is probably simpler than you think.
I'll help you fix it without spending much.
Quick Answer: Do Blackout Curtains Keep Cold Out?
Blackout curtains can reduce cold drafts and make a room feel warmer, but they do not fully stop cold air from coming in.
The result depends on the fabric quality, how well the curtain fits the window, and how it's installed. A poorly fitted curtain with side gaps will do very little.
A thick, floor-length curtain hung close to the wall works much better. Think of them as a helpful layer, not a complete fix.
They work best when used alongside other winter comfort steps like draft stoppers or weatherstripping.
How Blackout Curtains Help in Winter
Blackout curtains add a layer between you and your cold windows, and that layer does more than you might expect.
Reduce Heat Loss Through Windows
Windows let warm air escape faster than most walls do. Blackout curtains are made from thick, tightly woven fabric that slows this process down.
The fabric sits between the warm air inside and the cold glass outside. This reduces how quickly heat moves through the window. It won't stop all heat loss, but it does slow it down.
Over a full winter day, that can make a noticeable difference in how warm your room stays without turning up the heat.
Trap Warm Air Near the Window
When a blackout curtain hangs close to the window, it traps a small pocket of air between the fabric and the glass. That air acts like a buffer.
Cold air from outside has to pass through this layer before it reaches the rest of the room. This slows down cold air movement significantly.
The thicker the curtain and the tighter the fit, the more effective this buffer becomes. It's a simple physics trick that works without any extra products or cost.
Reduce Cold Window Sensation
Standing near a cold window makes the whole room feel colder, even if the temperature hasn't changed. This is because your body loses heat to the cold glass nearby.
A blackout curtain blocks that direct exposure. You no longer feel the chill radiating off the glass. The room might be the same temperature, but it feels noticeably warmer.
This is especially helpful in bedrooms and living rooms where you spend time close to windows.
Why Blackout Curtains Sometimes Don't Work Well
Not every blackout curtain will give you the cold protection you're hoping for. The fabric thickness matters a lot.
Thin blackout curtains are made primarily to block light, not to insulate. They offer very little thermal benefit. Gaps are another big problem.
If your curtain doesn't fully cover the window frame, cold air sneaks in from the sides, top, and bottom. Curtains that are too short or too narrow leave parts of the window exposed.
Poor installation, like hanging the rod too close to the window frame, reduces the insulating air layer and makes the curtain far less effective.
Blackout Curtains vs Thermal Curtains: Quick Comparison
Both block light, but only one is built to fight the cold.
| Feature | Blackout Curtains | Thermal Curtains |
| Main Purpose | Blocks light | Insulates temperature |
| Cold Control | Moderate | Strong |
| Summer Cooling | Good | Better |
| Best Use | Light control, sleep | Winter warmth, energy saving |
| Overall | Partial insulation | Best for cold protection |
Blackout curtains help reduce cold, but thermal curtains work better for keeping rooms warm in winter.
Do Blackout Curtains Keep Rooms Cooler in Summer Too?
Yes, and this is one of the reasons I personally like them year-round. In summer, sunlight coming through windows heats up a room fast.
Blackout curtains block that direct sunlight before it warms the air inside. This stops solar heat from building up during the hottest hours of the day.
Some blackout curtains come with a reflective backing that sends sunlight back out instead of absorbing it, which improves their cooling effect.
Over time, this helps reduce how much you rely on air conditioning, which is good for both comfort and energy costs.
Common Mistakes That Reduce Performance
Small errors in how you use blackout curtains can cancel out most of their benefits.
- Picking thin decorative blackout curtains: these block light but offer almost no insulation against cold.
- Leaving gaps around the edges: even a one-inch gap lets cold air pour straight in.
- Using curtains that are too short or narrow: poor coverage means large parts of your window stay exposed.
- Not closing curtains during peak cold hours:late evening and early morning are when you need them shut the most.
- Skipping proper installation: hanging the rod too close to the window frame kills the insulating air layer entirely.
Conclusion
I've tested a few curtains myself, and a thick, well-fitted blackout curtain makes a real difference on a cold night.
Do blackout curtains keep cold out completely? No. But they help more than most people expect.
If you've been sleeping cold or watching heating bills climb, this is a simple step worth trying. Give it a go and see how your room feels.
Drop a comment below, or share this with someone who needs a warmer home this winter.
Frequently Asked Questions
Do blackout curtains reduce heating bills?
Yes, they slow heat loss through windows, which can lower heating costs slightly over time.
Are blackout curtains better than thermal curtains for cold?
No, thermal curtains are specifically built for insulation and work better in very cold conditions.
How do I hang blackout curtains to block cold air best?
Hang them close to the ceiling, extend them beyond the window frame on all sides, and let them touch the floor.
Can blackout curtains block cold drafts?
They reduce drafts significantly when properly fitted, but won't fully stop air coming through gaps in the window itself.
Do blackout curtains work in summer to keep heat out?
Yes, they block sunlight and reduce heat gain, helping rooms stay cooler during hot days.
