How to Stop Light Coming In From the Sides of Curtains With 8 Easy Fixes

If you are trying to work out how to stop light coming in the side of curtains, check the window during daylight with the curtains fully closed. A clear strip of light beside the panel usually points to a coverage or hardware problem. Light visible through the fabric itself is a different issue and may require a blackout liner or blackout shade.

The most effective way to stop light coming in from the sides of curtains is to close the gap between the curtain edge and the wall. Small gaps can often be fixed with magnetic tape or removable fasteners. Larger gaps may require a different rod position, wider panels, or another window covering behind the curtains.

Why Is Light Coming Inside of My Curtains?

Blackout curtains can use highly opaque fabric and still leave light around their edges. The position of the rod and the amount of fabric covering the wall determine how much open space remains beside the window.

Curtain Rods Sit Too Far From the Wall

Curtain brackets hold the rod in front of the wall so the fabric can clear the window trim. If that distance is larger than needed, the outer edge of the curtain can sit well forward of the wall. The result is a narrow channel beside the curtain. Sunlight entering at an angle can remain visible even when the panel itself blocks light well.

Curtains Do Not Extend Far Enough Past the Window

When curtains only just cover the window frame, sunlight can easily enter around the outer edges of the panels. Wider curtains can improve coverage, but another option is to add Bringnox No-Drill Motorized Roller Shades 100% Blackout Vigor behind the curtains. 

The shade uses 100% blackout fabric and supports no-drill installation, so you can cover the glass area without first repositioning the curtain rod. By blocking direct light closer to the window, it also reduces the amount of sunlight reaching the gaps along the sides of the curtains. 

Curtain Panels Are Too Narrow

Curtains need to be wider than the window area they cover. If the panels are too narrow, they have to stretch across the rod when closed. This can leave small gaps at the outer sides of the window. With two curtain panels, narrow sizing can also create a gap where the panels meet in the middle. 

Curtains Do Not Return to the Wall

A curtain return is the small section of fabric that turns back toward the wall at each side. Without this return, sunlight can enter through the open space between the curtain edge and the wall. So the outer edge of a curtain should cover the space between the rod and the wall. If it hangs straight down from the end of the rod, a gap can remain behind the curtain.

How to Stop Light Coming Inside of Curtains

Choose the fix based on what is creating the gap. A curtain that already reaches the wall needs a different solution from one that stops close to the window frame. For rooms where you want adjustable daylight as well as privacy, zebra blinds can also sit behind curtains as a separate window treatment. 

1. Attach the Curtain Edges With Magnetic Tape

Magnetic tape is useful when the curtain reaches the wall but moves away from it after being opened or closed. Place the fastening points along the outer edge rather than across the entire panel.

This option requires very little change to the existing setup. Place the fastening points along the outer edge rather than across the entire panel. The connection should be strong enough to hold the fabric in position while still releasing easily when you want to open the curtains.

2. Use Velcro or Removable Hook-and-Loop Strips

Hook-and-loop strips give the curtain edge a more fixed connection to the wall or trim. They work well when magnets do not hold the fabric securely enough.

Apply short sections only where the gap appears. Covering the whole curtain edge can make everyday opening more awkward and places unnecessary pull on the fabric.

3. Create a Curtain Return With Hooks

A small hook near the outer edge of the window can pull the last section of the curtain back toward the wall. The panel then covers the side opening without requiring a new curtain rod.

This approach is most useful when the curtain already has some spare width. Position the hook where the fabric can reach it comfortably when the curtains are closed. Pulling the panel too tightly can distort the folds across the front of the window.

4. Install a Wraparound Curtain Rod

A wraparound curtain rod curves toward the wall at both ends. The curtain follows that shape instead of stopping at the front edge of a straight rod. This changes the path of the fabric around the window and gives the outer section somewhere to return. It is a more permanent solution for side gaps that come from the rod design itself.

5. Extend the Curtain Rod Past the Window Frame

Move the rod endpoints farther beyond the window opening when the closed curtains stop too close to the frame. This gives the panels more wall area to cover.

There is no single extension distance that works for every window. Check both sides before drilling new holes. A nearby corner, light switch, or piece of furniture may limit how far the rod can extend.

6. Use Wider Curtain Panels

Choose wider panels when the current curtains become tight or nearly flat after closing. Extra fabric gives the curtain enough material to cover the window while maintaining folds.

Use the full rod span as the starting point when ordering. Then check the curtain manufacturer's fullness recommendation because pleated panels and other heading styles use fabric differently.

If another shade will sit behind the curtain, its mount should be planned separately. Inside mount vs. outside mount blinds have different edge coverage because one sits within the opening while the other can overlap the surrounding trim or wall.

7. Bring the Curtains Closer to the Wall

Reducing bracket projection can help when the rod sits farther into the room than necessary. Open the window before changing the bracket position. Check handles and other moving parts so the new curtain position does not interfere with normal window operation.

If the existing brackets have a fixed projection, replacing them may be easier than modifying them.

8. Layer Curtains With Blackout Shades or Blinds

If a narrow strip of light keeps entering along the sides of a single curtain layer, adding a blackout shade closer to the glass can create a second barrier against incoming light. A shade sits near the window and blocks much of the incoming light before it reaches the curtain. The outer curtain then covers a wider area around the opening.

Bringnox Motorized Roller Shades 100% Blackout Westray uses 100% blackout fabric and can be customized to fit the window size. Installed behind the curtains, the roller shade blocks most direct light first, while the outer curtains help cover any light that may remain around the shade edges. This layered setup is especially useful in bedrooms, nurseries, or media rooms where a darker indoor environment is preferred. 

How to Prevent Side Light Gaps When Hanging New Curtains

Side gaps are easier to avoid before the rod and panels are ordered. Decide where you want the closed curtains to end, then measure the hardware and fabric around that finished coverage area.

If a blind or shade will also be installed, plan its measurements separately from the curtain measurements. The two treatments use different mounting points.

Measure Beyond the Window Frame

Start by measuring the actual window opening. Next, mark the area you want the closed curtains to cover on the surrounding wall.

Do not use the glass width as the curtain rod width. The rod needs enough space beyond the opening for the panels to cover the outer edges.

For a layered setup, measure windows for blinds according to the chosen mounting method. Inside-mounted shades depend on the dimensions and usable depth of the recess, while outside mounts are sized around the intended coverage area.

Record these measurements before ordering.

Choose Enough Curtain Width

Select the panel width after the rod span is known. This prevents a common sizing problem where curtains fit the window opening but do not have enough fabric for the finished installation.

Heading style also affects how much fabric is needed. Follow the recommended fullness for the specific curtain rather than applying one fixed ratio to every design.

Select Curtain Hardware That Reduces Side Gaps

Hardware should suit the finished curtain position as well as the curtain weight. Look at how far the brackets project from the wall and whether the rod ends allow a return.

Also check the usable wall surface before choosing an outside mounting point. Uneven trim or a nearby corner can affect where brackets can sit securely.

Test the full path of the curtains after installation. They should close without catching on the window hardware or pulling tightly across the rod.

FAQs

Can Side Light From Curtains Affect Sleep Quality?

Yes, it can. PNNL identifies reduced nighttime light intrusion as a benefit of window attachments for improved sleeping conditions. Side gaps matter most when outdoor light remains visible during your normal sleep period.

Can Curtain Side Gaps Make a Room Hotter?

Yes. Direct sunlight entering around the curtain can add solar heat near the window. PNNL notes that interior window attachments can reduce heat gain, although results depend on the covering and how it is used.

Are Blackout Curtain Liners Effective for Side Light?

Only partly. A blackout liner helps stop light passing through the curtain fabric. It cannot close an open space between the curtain edge and the wall.

Should Curtains Touch the Wall for Better Blackout Performance?

They should sit close to the wall where side light enters. Continuous contact is unnecessary. A curtain return or small fastener can close the side opening while allowing normal curtain movement.

Conclusion

Side light usually remains because the curtain does not cover enough of the area around the window or sits too far from the wall. Match the fix to the gap instead of replacing the entire window treatment immediately.

Use a removable fastener for a small opening. Change the rod position or panel width when coverage is the real problem. For stronger room darkening, a properly sized blackout shade behind the curtains can add another layer of light control.