We Reviewed IKEA and Walmart Blackout Curtains. Here's How Much Light They Actually Block.

Last updated: February 2026

TL;DR: We analyzed the top-selling IKEA blackout curtains (MAJGULL, KORGMOTT, BENGTA) and Walmart's Mainstays blackout curtains using lab data, manufacturer specs and thousands of customer reviews. The fabric blocks 85-99% of light depending on color. But every curtain leaks light around the edges, top and bottom, where fabric meets wall. A 2022 Northwestern study found that even moderate light during sleep raises heart rate and insulin resistance. For true 100% light blocking, you need a sealed edge system, not thicker fabric.

You bought "blackout" curtains and your room is still not dark

You did the research. You picked the highest-rated blackout curtains at IKEA or Walmart, hung them up, closed them and waited for pitch black. Instead, you got a glowing halo around every edge of the window, a bright strip along the top where the rod sits and enough light seeping in to read a book by 6 a.m.

You are not imagining it and you did not buy the wrong product. This is how every blackout curtain works. The fabric itself blocks light. The problem is everywhere the fabric is not: the top, sides and bottom where curtain meets wall.

We dug into Consumer Reports' lab testing data, manufacturer specifications and over 10,000 combined customer reviews from IKEA and Walmart to find out exactly how much light these bestselling curtains actually block, where they fail and what the science says about that remaining sliver of light.

What we reviewed and how we evaluated each curtain

We selected the four most popular blackout curtain options across both retailers based on sales rankings, review volume and price range. Our evaluation focused on two separate factors: how well the fabric blocks light and how well the curtain as a whole darkens a room. Those are two very different measurements and the gap between them is the entire point.

We cross-referenced Consumer Reports' lab testing (which used a 5,000-lumen flashlight pressed directly against each fabric), manufacturer product descriptions and real customer reviews that reported specific light-blocking performance.

The products we reviewed:

• IKEA MAJGULL Blackout Curtains ($29.99-$44.99/pair, 4.4-4.6 stars)
• IKEA KORGMOTT Blackout Curtains ($29.99/pair, 4.5 stars)
• IKEA BENGTA Block-out Curtain ($19.99/piece, 4.4 stars)
• Walmart Mainstays Blackout Curtains ($9.96-$16.97/pair, 4.4 stars)

How each curtain performed: fabric versus total room darkening

All four blackout curtains blocked most light through the fabric itself, but total room darkening told a different story. Consumer Reports' lab testing confirmed a consistent pattern across brands: darker curtain colors blocked more light than lighter ones. That finding held true for every brand they tested, including IKEA and Mainstays.

Here is what stood out from the individual reviews.

IKEA MAJGULL

The strongest all-rounder for general use. Customers consistently praise the soft, heavy drape and room darkening effect. One reviewer in Colorado measured roughly 85-90% light blocking in a very sunny condo, noting they darken the room well but do not block 100% of light. Another reported the curtains worked for nighttime light but "the only light that comes in is from around the edges."

IKEA KORGMOTT

Performed well through the fabric, with IKEA describing it as blocking "all light and glare on TV/screens." Multiple reviewers confirmed good light blocking, though several noted the material felt more like a trench coat than a curtain.

IKEA BENGTA

Uses a laminated backing that is effective at blocking light through the material. However, multiple reviewers reported pinholes developing in the lamination, with one noting that "light comes through little holes all over the curtain, almost like stars." Another described the plastic backing as a separate layer from the actual curtain material.

Walmart Mainstays

Remarkable value at under $17 for a pair. The fabric does reduce light significantly. But Walmart's own AI-generated review summary describes the product as "Partially light blocking: Blocks some to most of the light." That is the retailer's system summarizing a "blackout" product as partial.

One reviewer who bought four panels for a guest bedroom wrote that while they helped, they "would NOT recommend for babies, sleep training, or anyone working night shift."

Where every curtain failed: the edge gap problem

Every curtain we reviewed leaked light around the edges, because fabric hanging from a rod physically cannot seal against a wall. This is not a quality defect. It is an architectural limitation that affects all rod-hung window treatments, regardless of brand or price point.

IKEA knows this. Their own product pages include the instruction: "For best effect, mount from ceiling to floor with the curtains overlapping the window, as close as possible, to prevent gaps." Their spokesperson told Consumer Reports that curtain rods and curtains should "extend well beyond the window's edges" to minimize light leakage.

But even following that advice perfectly, there is no configuration where a flexible piece of fabric conforms flat to a wall on all four sides:

• Top gap: The rod holds the curtain away from the wall, creating an open channel where light pours over the top
• Side gaps: Gravity pulls fabric straight down, but the wall angles away at the edges, leaving 0.5-2 inches of open space on each side
• Bottom gap: The curtain either puddles on the floor (still not sealed) or hangs above it (completely open)

You can tack curtains to the wall, use magnetic strips or install wraparound rods and you will still have gaps. A standard 57-inch curtain with even modest gaps on all four sides creates roughly 60 square inches of open space where unfiltered light enters freely. During a bright morning, that is more than enough to push your bedroom to 50-100 lux.

And 50-100 lux is exactly where the health consequences begin.

Why that remaining light actually matters for your health

That 5-15% of light leaking around your blackout curtains is not just an annoyance. Peer-reviewed research shows it is enough to measurably disrupt your body while you sleep.

Heart rate and insulin resistance: A 2022 Northwestern University study published in PNAS found that a single night of sleeping with moderate light exposure (100 lux, roughly equivalent to a dim living room) increased participants' heart rates during sleep, activated the sympathetic nervous system and raised insulin resistance the following morning.

Long-term mortality risk: A larger-scale 2024 study by Windred et al., also published in PNAS, tracked 89,000 UK Biobank participants using 13 million hours of light sensor data. Those exposed to brighter nighttime light had significantly higher premature mortality risk, particularly from cardiometabolic causes.

Children are even more vulnerable: A 2022 CU Boulder study published in the Journal of Pineal Research found that even very dim light (5-40 lux) suppressed melatonin production by 78% in preschool-aged children. Their melatonin levels did not recover for over 50 minutes after the light source was removed.

Melatonin suppression in adults: A 2011 study by Gooley et al. in the Journal of Clinical Endocrinology & Metabolism showed that exposure to typical room light (under 200 lux) before bedtime suppressed melatonin by more than 50% in 116 participants.

The pattern is consistent: any light during sleep, even moderate amounts, triggers measurable physiological responses. The light leaking around your IKEA or Walmart blackout curtains is not a minor inconvenience. It is actively interfering with your body's ability to rest and repair.

This is why UBlockout's Ultimate Blackout Shade uses a sealed track system. Instead of hanging fabric from a rod and hoping it covers the gaps, the shade fabric runs inside aluminum channels on both sides, seals at the top inside a headbox and meets a sealed bottom bar. There are no gaps for light to enter. The result is verified 100% light blocking, not 85-95%.

The verdict: are IKEA and Walmart blackout curtains worth buying?

For general room darkening, both IKEA and Walmart offer solid options at fair prices. But for true blackout, none of them can get you there.

To give credit where it is due:

• IKEA MAJGULL has the best overall fabric quality and drape in this group. In darker colors it creates a genuinely darker room for everyday use.
• IKEA KORGMOTT offers good value with a more textured, modern aesthetic.
• Walmart Mainstays at under $17 for a pair is hard to argue against for casual light reduction in living rooms or home offices.

Where to draw the line

If you want your room darker: Any of these curtains will improve your situation over bare windows. Choose the darkest color available and mount the rod as high and wide as possible.

If you need your room dark: Curtains cannot solve the problem. The fabric is not the issue. The gaps are. You need a system that seals light at every edge.

UBlockout's Ultimate Blackout Shade achieves true 100% light blocking through its patented sealed track technology, backed by 600+ five-star reviews and the National Sleep Foundation's 2024 SleepTech Award. For additional light sources in the room like device LEDs, power indicators and alarm clock displays, LED Light Blocker Stickers handle the rest.

The difference between 90% blackout and 100% blackout is not 10%. It is the difference between a room that looks dark and a room that is dark.

Key takeaways

• IKEA and Walmart blackout curtains block 85-99% of light through the fabric, depending on color and model
• Every curtain leaks light around the top, sides and bottom where fabric meets wall
• A 2022 Northwestern study found that even moderate light during sleep raises heart rate and increases insulin resistance
• For general room darkening on a budget, these curtains are a reasonable choice
• For true 100% blackout, sealed track technology is the only design that eliminates edge gaps entirely

Ready for a room that is actually pitch black? Explore the Ultimate Blackout Shade.

Frequently asked questions

How much light do IKEA blackout curtains actually block? IKEA blackout curtains block most light through the fabric, with darker colors performing best. Customer reports and lab data suggest 85-95% total room darkening. Light primarily leaks around the edges where the curtain meets the wall, not through the material itself. IKEA's own installation guidance acknowledges these gaps.

Are Walmart Mainstays blackout curtains any good? Mainstays blackout curtains offer effective light reduction at an unbeatable price, starting under $10 per pair. They block most light through the fabric but leave gaps at the edges like all rod-hung curtains. Walmart's own review summary describes them as "partially light blocking." Best suited for living rooms and general use.

Why do my blackout curtains still let light in? Light enters around the top, sides and bottom where curtain fabric cannot seal against the wall or window frame. This is a design limitation of all rod-hung curtains, not a quality defect. Even ceiling-mounted, extra-wide curtains leave gaps. Sealed track systems solve this by capturing fabric edges inside aluminum channels.

What percentage of light do blackout curtains block? Quality blackout curtains block 95-100% of light through the fabric alone. Total room darkening, however, typically reaches only 85-95% because of edge gaps around the curtain perimeter. The remaining 5-15% enters freely around the top, sides and bottom. Sealed track blackout shades achieve 100% by eliminating these gaps.

Do darker blackout curtains work better than lighter ones? Yes. Consumer Reports lab testing confirmed that darker curtain colors blocked more light than lighter ones across every brand tested, including IKEA and Walmart Mainstays. If choosing curtains, selecting the darkest available color in your preferred style will maximize light blocking performance through the fabric.

What blocks 100% of light from a window? The only window treatments that block 100% of light use sealed track or channel systems that eliminate gaps between the covering and the wall. Standard curtains, blinds and roller shades all leave edge gaps regardless of fabric density. Sealed track technology captures shade fabric inside aluminum channels on all sides for zero light leakage.