Angled Curtains: How to Measure Your Windows and Choose the Right Custom Solution

Finding curtains for angled windows can feel complicated. Standard curtain panels rarely follow a sloping window shape, and the mounting position, curtain length and pleat style all affect the finished result.

At Wellmira, we create custom angled curtains and matching curtain rail systems. Our projects include A-frame window curtains, apex window curtains, triangular window curtains and solutions for trapezoidal windows, as well as curtains for sloping, vaulted and cathedral ceilings.

Whether you call them curtains or drapes, the starting point is the same: a solution designed around your window’s shape and the way you want to use the space.

We consult online, guide you through the measurements and ship custom curtains and rails worldwide. Here are our practical tips for planning your project.

1. How to Measure for Angled Window Curtains

The most important measurements are the lengths of the sloping sections where the curtain rails will actually be installed.

These may differ from the dimensions of the glass or window frame. A curtain track fitted inside a window recess requires different measurements from one mounted above or outside the opening.

Before measuring, decide—or ask us to help you decide—where the curtain system should sit.

Depending on your project, we may need:

• The length of each planned sloping rail section.

• The total width the curtains need to cover.

• The required curtain lengths, measured from the planned attachment points to the floor.

• The space available around the window for mounting and gathering the fabric.

For slanted or angled windows, the required curtain length may vary across the window. A photograph helps us identify which measurements you need.

Trapezoidal Window Curtains

Trapezoidal windows, also called trapezoid windows, require a curtain shape that follows their individual proportions. Measure the planned rail position rather than assuming the window frame dimensions will be sufficient.

[PHOTO 1 — Trapezoidal window with the required measurement lines marked]

Measure the sloping rail section and the relevant curtain lengths using the guide prepared for your window.

Curtains for Slanted or Sloped Windows

A window with a single sloping top has a higher and a lower side. These windows may also be described as angled-top windows or rake windows.

For this configuration, both the sloping rail length and the curtain lengths at the specified positions matter.

[PHOTO 2 — Single-slope window with the required measurement lines marked]

The rail position and the difference between the higher and lower sides help define the custom curtain shape.

Apex, Triangular and A-Frame Window Curtains

Apex windows rise to a peak. Triangular glazing and windows in A-frame homes can require similar planning, although their exact shapes differ.

Measure each sloping section separately. Do not assume that both sides have identical dimensions.

[PHOTO 3 — Apex or A-frame window with the required measurement lines marked]

For a peaked window, measure both planned rail sections and the curtain lengths indicated in your project guide.

Gable-End Windows and Windows Beneath Vaulted Ceilings

Large gable-end windows and glazing beneath cathedral or vaulted ceilings can extend across more than one storey.

Confirm the mounting position before measuring. The surrounding ceiling and walls matter just as much as the window itself.

[PHOTO 4 — Tall window beneath a vaulted or cathedral ceiling, with measurement lines marked]

For tall installations, measure the planned rail sections and curtain lengths from the actual attachment positions.

These examples illustrate different configurations. We prepare measurement guidance for your particular window and installation.

2. Consider Mounting Outside the Window Recess

Where space allows, we often recommend extending the curtains beyond the window opening instead of fitting the entire system inside the recess.

This creates room to gather the fabric into attractive folds using curtain tiebacks and wall-mounted curtain holdback hooks.

Wider coverage can also help reduce light entering around the edges of the curtains.

The right position depends on the ceiling slope, surrounding walls and your preferred arrangement. Tell us whether your main priority is privacy, light blocking, decorative draping or a combination of these.

3. How Angled Curtain Rails and Tracks Are Shipped

Our angled curtain rails are shipped in sections of up to 140 cm (approximately 55.1 inches). Longer curtain tracks consist of several connected sections.

If a measurement error leaves a rail too long for its intended position, shortening it may be possible. Contact us before making changes so we can guide you on the appropriate approach.

Accurate measurements are still essential. Shortening a rail can help with excess length, but it cannot correct every fitting issue.

4. Extra-Long Curtains: Should the Fabric Rest on the Floor?

Tall angled windows can be difficult to measure accurately. The longest curtain we have made was 6.5 metres—approximately 21 feet 4 inches.

With extra-long curtains for high ceilings, small measurement differences or uneven floors can become noticeable.

If you like fabric resting on the floor, pooled curtains, also called puddled curtains, can create an elegant finish while making small height differences less visible.

Our Tip: Allow Approximately 15 cm for Pooling

For this look, we may recommend adding around 15 cm (approximately 6 inches) to the planned floor-length curtain measurement.

Measure from the intended curtain attachment point to the floor, then agree on the additional length with us.

The extra fabric can help make small variations of 1–2 cm (approximately 0.4–0.8 inches) less noticeable.

[PHOTO 5 — Completed Wellmira angled curtains with fabric pooling on the floor]

Additional length creates a soft pooled finish and helps accommodate small variations in measured height or floor level.

Pooling is a styling choice. If you prefer curtains that finish at floor level, let us know before we prepare your project.

For larger, fuller folds, we also consider fabric width, fullness and heading style. Extra length alone does not create that effect.

5. How to Plan Blackout Curtains for Angled Windows

For angled blackout curtains, both the fabric and the installation matter.

Blackout fabric or blackout lining helps block light passing through the curtain. Gaps around the top and sides can still let light into the room.

Choose Ceiling-Mounted Curtain Tracks Where Possible

We particularly recommend ceiling mounting when the ceiling geometry and mounting surface allow it.

If ceiling mounting is not possible, consider a wall-mounted curtain rail close to the ceiling or, where practical, at least 5 inches (12.7 cm) above the top of the window.

Mounting above the opening creates overlap and helps reduce light entering over the curtain.

Extend the Curtains Beyond the Window Edges

Where space permits, allow the curtains to cover beyond both sides of the opening.

This overlap helps reduce the bright strips of light that can appear around the fabric.

Consider Blackout Lining

If you prefer a dimout or medium-density decorative fabric, we can add blackout lining where suitable for your project.

Tell us how much light control you need. We will help you choose the fabric, lining and mounting arrangement together.

The final level of darkness depends on the complete installation, including any gaps around the curtains.

6. Which Curtain Pleats Work Best on Sloping Ceilings?

The slope of the rail affects how the curtain heading and folds sit.

We offer different heading styles for custom drapery, but the most suitable option depends on the angle and the overall configuration.

For Steep Slopes: Pencil Pleat with Secured Pleats

For strongly sloping installations, we usually recommend our Pencil Pleat heading with specially secured, sewn-in pleats.

We shape the gathers and secure them with stitching to help maintain an even arrangement. This is especially useful on steep angled curtain tracks, where ordinary gathered pleats can be harder to keep in position.

[PHOTO 6 — Close-up of Wellmira’s Pencil Pleat heading tape with specially secured pleats]

The gathers are shaped and stitched to help the Pencil Pleat heading retain its arrangement on a steep slope.

This construction helps preserve the pleat arrangement through use and rehanging. Follow the care instructions supplied for your particular curtain fabric.

For Gentler Slopes: More Heading Options

For curtains under a gently sloping ceiling, suitable options may include:

• Pencil Pleat.

• Wave or Ripple Fold.

• Double Pinch Pleat.

• Triple Pinch Pleat.

We assess the heading together with the rail system, fabric and desired appearance.

If you have a particular style in mind, send us reference photographs so we can discuss how it would work in your space.

7. Room Divider Curtains for Sloped Ceilings

Custom angled curtains are useful for more than windows. We also make room divider curtains for spaces beneath sloping ceilings.

For room division, we generally recommend a dense fabric. Depending on the project, options such as our Blackout Top fabric can provide privacy, block light through the fabric, help reduce drafts and absorb some reflected sound.

A fabric divider does not provide the same sound isolation as a solid wall. Tell us what you want to achieve so we can recommend an appropriate construction.

Choose Fabric That Looks Attractive on Both Sides

A room divider is visible from both directions. We recommend choosing fabric with the same or a similar appearance on its front and reverse.

If you need additional lining, discuss the appearance of both sides with us. Lining can change the colour or texture visible from the adjoining space.

Consider Transparent Curtain Heading Tape

For a neater reverse side, we recommend transparent heading tape where suitable.

This avoids the prominent white stripe that conventional white tape can create and helps the curtain look attractive from both areas of the room.

Tell us from the beginning that your curtain will be used as a room divider, so we can consider both sides when planning it.

8. How to Order Made-to-Measure Angled Curtains Online

You do not need to work out every technical detail before contacting us.

Start with a clear photograph of your window or the space you want to divide. Include the surrounding ceiling, walls and floor wherever possible.

Our online consultation process is straightforward:

1. Send photographs and describe your wishes. Tell us about your priorities, such as privacy, blackout coverage, floor pooling or room division. Include reference images if you have them.

2. Receive measurement guidance. We mark the measurements needed on your photograph.

3. Take and send the measurements. Follow the guide prepared for your configuration.

4. Agree on your custom solution. We help you choose the fabric, pleats, curtain rails and finished lengths. Pricing is confirmed once the required measurements and project specifications are established.

5. Receive your curtains and rails. We manufacture the agreed solution and ship it worldwide.

Our experience with bespoke angled curtains helps us guide you through details that are easy to overlook—from measuring the actual rail position to choosing a heading for a steep slope.

Ready to plan your custom window treatments? Send us a photo through our angled curtain enquiry form or directly to wellmira@wellmira.com, together with your wishes and reference images. We will help you identify what to measure and choose a solution for your space.

Angled Curtain Projects in Our Customers’ Homes

See how our custom curtains look in real homes. Use these customer photographs as inspiration, and tell us which details you would like to include in your project.

[PHOTO 7 — Customer photograph of a completed Wellmira angled curtain project]

[PHOTO 8 — Customer photograph of a completed Wellmira angled curtain project]

[PHOTO 9 — Customer photograph of a completed Wellmira angled curtain project]

[PHOTO 10 — Customer photograph of a completed Wellmira angled curtain project]