How to Make Curtains Blackout: A Complete Practical Guide

Curtains are a significant way to enhance the elegance and privacy of your space. However, some curtains let in more light than you would like. If you are facing the same problem, you are not alone. Whether it is the early morning sun disrupting your sleep, streetlights glowing through your bedroom window at night, or simply the need for better privacy, finding a reliable solution matters.

The good news is that you do not always need to replace your existing curtains entirely. There are several proven ways to make curtains blackout, ranging from simple DIY methods to more permanent upgrades. Whether you have ready-made panels or custom curtains, these solutions can significantly improve light control without the cost of buying new window treatments. Additionally, you don’t need to search for those methods. This guide walks you through all of them clearly and honestly.

Before diving into methods, it helps to understand what you are actually trying to achieve. Blackout does not always mean complete darkness. There are different levels of light blocking, and knowing which one you need will help you choose the right approach.

• Light filtering – reduces glare but does not block light significantly
• Room darkening – blocks most light but allows some to pass through edges and fabric
• True blackout – blocks up to 99% of light when properly installed with minimal gaps

Most people searching for how to make curtains blackout are looking for room darkening to full blackout results. The method you choose will largely depend on your budget and how permanent you want the solution to be. Additionally, it also depends upon whether you are working with existing curtains or starting fresh.

Here are the easy and effective methods to make your curtains blackout:

Method 1: Add a Blackout Lining to Existing Curtains

This is the most popular and effective method for converting regular curtains into blackout curtains. Instead of buying new curtains, you simply attach a blackout lining to the back of your existing ones.

What You Will Need

• Blackout lining fabric (available at most fabric stores or online)
• Scissors
• Measuring tape
• Sewing machine or fabric glue
• Pins

Step-by-Step Process

Here is the step-by-step guide to add the blackout lining to your existing drapes:

Step 1: Measure Your Curtains Accurately
Lay your curtain flat on a clean surface and measure the width and length. Cut your blackout lining fabric to match these dimensions. It is advisable to leave about one to two centimetres extra on each side to allow for a neat hem.

Step 2: Prepare The Lining
Fold the edges of the blackout lining over by about one centimetre and press them flat with an iron. This creates a clean edge that sits neatly against the curtain fabric.

Step 3: Attach The Lining
Place the blackout lining against the back of the curtain with the wrong sides facing each other. Pin them together carefully to prevent shifting. At this stage, you have two options depending on your skill level and preference.

• Sewing method – Stitch the lining to the curtain along the edges using a sewing machine. This creates a durable, long-lasting result that looks professional.
• Fabric glue method – If you do not own a sewing machine or prefer a no-sew approach, use a strong fabric glue or hem tape along the edges. This works well for lighter fabrics and is a great option for renters.

Step 4: Rehang Your Curtains
Once the lining is attached and fully dry or stitched, rehang your curtains as normal. The blackout lining sits discreetly at the back, preserving the look of your original curtains from the front.

Expert Tip

Always choose a blackout lining that is at least as wide as your curtain panel, ideally slightly wider. A lining that is too narrow will leave gaps at the edges where light can seep through, which defeats the purpose entirely.

Method 2: Use Blackout Curtain Liner Panels

If sewing is not your thing, blackout liner panels are a brilliant alternative. These are ready-made panels designed to hang behind your existing curtains using the same curtain rod or a separate one.

They require no sewing, no glue, and no special tools. You simply hang them, and you are done. Many liner panels come with their own header tape or ring holes, making installation straightforward even for complete beginners.

Things to Consider

• Make sure the liner panel is wide enough to cover the full width of your window, including a few centimetres of overlap on each side
• Check that the liner length reaches the floor or the window sill to prevent light from entering at the bottom
• Some liner panels are slightly thinner than sewn-in linings, so layering two panels can improve the blackout effect significantly

This method works particularly well in rental properties where you cannot make permanent alterations to the walls or curtains.

Method 3: Apply Blackout Curtain Tape or Iron-On Hem Tape

For a no-sew solution that still offers a relatively permanent result, blackout curtain tape and iron-on hem tape are worth considering. These adhesive products bond the lining directly to your curtain fabric using heat or pressure, eliminating the need for any stitching.

This approach is best suited for lightweight to medium-weight curtains. Heavy velvet or thick woven fabrics may not bond as effectively. Moreover, the adhesive can sometimes struggle under the weight over time.

Method 4: Install a Blackout Roller Blind Behind Your Curtains

Sometimes, the most practical solution is to add a secondary layer of window covering rather than modifying your curtains at all. Installing a blackout roller blind directly behind your curtains gives you flexibility, full light control, and a clean finish.

During the day, you can roll the blinds up completely and let your curtains do their decorative job. At night, simply lower the blind for complete darkness while keeping your curtains drawn for an extra layer of coverage.

This layered approach is particularly popular in:

• Bedrooms where complete darkness is essential for sleep quality
• Nurseries and children’s rooms where nap times happen during daylight hours
• Home cinema rooms where light control is critical for screen visibility
• Shift workers’ bedrooms, where daytime sleep is a regular necessity

Method 5: Use Blackout Fabric to Make Curtains from Scratch

If you have basic sewing skills, making blackout curtains from blackout fabric offers a fully custom solution. You have full control over the size, colour, weight, and style of the finished curtain.

How to Choose the Right Blackout Fabric

Not all fabrics labelled as blackout perform the same way. When shopping for blackout fabric, look for the following:

• Triple weave blackout fabric – one of the most effective options, using three layers of tightly woven fibres to block light, reduce noise, and provide insulation
• Foam-backed blackout fabric – features a coating on the back that blocks light effectively, though it can feel slightly stiffer than triple weave
• Thermal blackout fabric – designed to block both light and heat, making it a smart choice for rooms that overheat in summer

Always request a fabric sample before purchasing a large quantity. Hold it up to a bright light source and observe how much light passes through. A quality blackout fabric should show little to no light transmission.

Basic Sewing Guide for Blackout Curtains

Follow these steps to sew your blackout drapery:

1. Calculate Your Fabric Requirements

For a full and generous look, your curtain width should be approximately one and a half to two times the width of your window. For length, measure from the curtain rod to where you want the curtain to fall, then add an extra fifteen centimetres for the header and hem allowances.

2. Cut Your Fabric Panels

Use sharp fabric scissors and cut in a straight line. An uneven cut will result in curtains that hang crookedly, so take your time with this step.

3. Hem the Sides And Bottom

Fold each side edge over by about two centimetres, press flat, and stitch in place. Repeat for the bottom hem. A double hem at the bottom adds weight, which helps the curtain hang more neatly and reduces light gaps at the floor.

4. Create The Header

The header is the top section of the curtain through which the curtain rod passes or where hooks and rings attach. Fold the top edge over by at least eight to ten centimetres and stitch across to create a rod pocket, or attach curtain heading tape if you prefer a pleated or pinch-pleat style.

5. Hang And Adjust

Once your curtains are complete, hang them and check for any light gaps. Minor adjustments to the header or hem can address most issues at this stage.

Even the best blackout curtains can allow light to enter through the sides, top, and bottom if they are not installed correctly. This is one of the most common frustrations people experience, and it is entirely preventable.

Practical Solutions for Light Gaps

Consider the following tips to minimise the light gaps in your curtains:

1. Extend the curtain rod beyond the window frame

Mount your curtain rod at least fifteen to twenty centimetres beyond the window frame on each side. This allows the curtain fabric to overlap the wall rather than just the glass, blocking the light that would otherwise sneak in from the sides.

2. Hang curtains higher than the window

Position the curtain rod as close to the ceiling as possible rather than just above the window frame. This eliminates the gap at the top where early morning light often enters first.

3. Use a valance or pelme

A valance or pelmet fitted above the curtain rail covers the gap between the top of the curtain and the ceiling. This simple addition can make a noticeable difference in how much light enters the room.

4. Add magnetic curtain weights or floor seals

Light that enters from the bottom of a curtain is a surprisingly common problem, especially on windy days when curtains shift slightly. Curtain weights sewn into the hem keep the fabric pressed against the floor or sill, significantly reducing this issue.

5. Consider a curtain with a return

A return is when the curtain wraps around the end of the curtain rod and meets the wall. This eliminates side gaps and is a particularly effective technique for achieving near-total darkness.

Even with the best materials and intentions, a few common errors can undermine your blackout curtain project.

1. Choosing the wrong lining weight

A lining that is too thin will not block light effectively regardless of how well it is attached. Always opt for a lining specifically marketed as blackout rather than a standard curtain lining.

2. Ignoring the edges

Many people focus entirely on the fabric itself and overlook the gaps at the sides, top, and bottom. Light is persistent and will find any gap available. Addressing the edges is just as important as choosing the right fabric.

3. Buying curtains that are too narrow

A curtain that barely covers the window will always allow light to enter at the sides. Generous width is essential for both light blocking and a visually appealing finish.

4. Using fabric glue on heavy fabrics

Fabric glue works well on lightweight materials but can fail over time when used on heavy curtains. If your curtains are thick or heavy, a sewn lining will always be the more reliable option.

Choosing the best approach depends on a few key factors.

Situation	Best Method
You have existing curtains you love	Add a sewn-in or clip-on blackout lining
You rent and cannot make permanent changes	Use ready-made liner panels or a roller blind
You want a completely custom result	Sew blackout curtains from scratch
You need a quick and budget-friendly fix	Iron-on hem tape with blackout lining fabric
You need maximum darkness with no compromise	Layer curtains with a blackout roller blind

Making your curtains blackout does not have to be complicated or expensive. You just have to apply the appropriate method. Whether you choose to add a lining to your existing curtains, hang ready-made liner panels, or sew a custom set from scratch, selecting high-quality materials is important. Additionally, Thoughtful installation is equally essential for achieving the best results.

The fabric itself is only part of the solution. How you hang your curtains and how well you address the gaps around the edges will ultimately determine how dark your room gets. Start with whichever method suits your skill level and budget. Moreover, address those edge gaps, and you will notice a dramatic improvement in light control almost immediately.

Yes, in most cases. As long as the curtain fabric is not sheer or extremely lightweight, you can add a blackout lining to virtually any curtain. Very sheer fabrics may not provide enough structure for a lining to attach cleanly. So in those cases, a separate blackout blind is the better solution.

They can. Thicker blackout fabrics, particularly triple weave and thermal varieties, offer a degree of sound dampening and thermal insulation. They are not a replacement for proper soundproofing or insulation. However, they can make a noticeable difference in rooms facing busy streets or experiencing significant temperature fluctuations.

Always check the care label on both the curtain fabric and the lining before washing. Most blackout linings should be washed on a gentle cycle in cool water. Avoid tumble drying at high heat, as this can damage the coating on foam-backed linings. If in doubt, hand washing or dry cleaning is the safest option.

No curtain alone can block 100% of light. Even the best blackout curtain fabric will allow a small amount of light to enter through gaps around the edges unless the installation specifically addresses this. With proper installation techniques such as extended curtain rods, ceiling-height hanging, and curtain returns, you can get extremely close to complete darkness.