Struggling with Casement Window Sizes? Our Chart Has Answers

Selecting the right size casement windows for your home can be a frustrating experience. With so many options and confusing sizing charts, it’s easy to end up with windows that don’t fit or aren’t optimized for your space. Accurately measuring your window openings is key – fall short and you’ll end up with unsightly gaps, go too big and the windows may not even fit. But armed with the right information, including some expert tips and our handy size reference guide, you can take the guesswork out of casement window sizing.

What Are Casement Windows?

Before diving into sizes, it helps to understand exactly what casement windows are. Casements are hinged windows that open along one side, usually with a hand crank mechanism. The hinges can be placed either vertically or horizontally depending on the orientation and design of the window. When open, the sash opens outward from the building similar to a door. This allows for full, unobstructed views and excellent ventilation.

Casements are extremely energy efficient due to their airtight seal when closed. And unlike sliding windows, the sash closes firmly against the window frame on all sides. When combined with triple pane glass options, casement windows can meet the highest efficiency standards. Their crank handles also make them easy to open and close at tall heights.

Casement Window Size Basics

The most common way to designate casement sizes uses two numbers to represent the width and height dimensions in feet. For example, a 3×5 casement describes a window that is 3 feet wide by 5 feet high. Standard size increments allow homeowners to choose the closest fit for their needs. Custom-sized casements, while more expensive, match exact specifications.

Width Dimensions

Some of the most popular standard casement window widths include:

casement window sizes chart
  • 12 inches (1’0″)
  • 15 inches (1’3″)
  • 18 inches (1’6″)
  • 21 inches (1’9″)
  • 24 inches (2’0″)
  • 27 inches (2’3″)
  • 30 inches (2’6″)
  • 36 inches (3’0″)

These sizes allow between 14″ to 38″ widths. The smallest casement width is usually 14 inches (1’2″) while custom sizes can go all the way up to 6 feet wide.

Height Dimensions

Popular standard casement window heights include:

  • 15 inches (1’3″)
  • 18 inches (1’6″)
  • 21 inches (1’9″)
  • 24 inches (2’0″)
  • 30 inches (2’6″)
  • 36 inches (3’0″)
  • 48 inches (4’0″)
  • 60 inches (5’0″)
  • 72 inches (6’0″)

The typical height range is between 16 inches and 72 inches. Specialty windows go up to 9 feet tall for a dramatic floor-to-ceiling effect.

Standard vs. Custom Sizes

Homeowners aiming for fast installation with simpler needs can benefit from choosing standard window sizes that match common building practices. Because manufacturers mass produce these sizes, they cost less and ship faster – usually within 5 business days. Standard windows also allow easy swapping with most existing models.

For unique homes, openings, or layouts, custom-sized casements provide an exact fit. These made-to-order windows can match anything from oddly shaped corners to historic divided light patterns. Custom sizes excel when combined with curved walls or matching a specific design aesthetic. Just be prepared to pay 50-100% more and wait up to 6 weeks for specialty manufacturing.

Measuring Casement Window Openings

When preparing to swap existing casement windows or cut an opening for new full-frame installations, careful measurement ensures proper sizing and fit. Follow these steps for accurate dimensions:

Tools and Methods

Start by gathering a steel tape measure and a 4-foot level. For existing windows, fully open the sashes – this exposes the entire frame for measuring. Stretch the tape vertically from the highest point of the frame from top to bottom. Then measure horizontally left to right. For new openings, mark the rough opening and measure between the studs.

Allowance for Installation and Adjustments

When ordering, add between 1/4 and 1/2 inch to your measurements to allow room for out-of-square openings and shimming during installation. This prevents undersized gaps while providing wiggle room to ensure operation and seals.

Typical Casement Configurations

Casement windows can be combined into different orientation and layouts:

Horizontal Casements

Positioning casements side-by-side stretches views wider. Great for letting in views without taking over an entire wall. Multiple horizontal units create an appealing uniform look.

Vertical Casements

Stacking casement windows from floor to ceiling draws the views upward, delivering breathtaking views. Tall vertical casement combinations feature clean sightlines.

Combined with Other Windows

Casements pair nicely with double hung and fixed windows to create diminished light patterns. Mixing shapes adds architectural interest while allowing optimal views and natural light.

Casement Window Size Chart

SizeWidth (Inches)Height (Inches)Recommended Opening Width (Inches)Recommended Opening Height (Inches)
1’6″ x 2’0″182418 1/4″24 1/4″
2’0″ x 3’0″243624 1/4″36 1/4″
2’6″ x 4’0″304830 1/4″48 1/4″
3’0″ x 5’0″366036 1/4″60 1/4″

Use this handy reference chart of common casement sizes when determining the closest option for your window openings. Then match to the recommended rough opening dimensions to allow room for installation.

Window Size Recommendations By Location


Kitchens benefit from larger horizontal casements around 36-48″ wide to maximize views and daylighting on countertop surfaces. Heights around 36-48″ facilitate ventilation and visibility. Consider multiple groupings to stretch the entire sink or prep area.


In bathrooms, mirrored casements 24-30″ wide by 48-60″ tall open views while maintaining privacy with obscured glass. Vertical orientations work well around existing mirrors and plumbing.


Stack high vertical casements 60″ and taller to take bedrooms views up. For side windows, combine 30-36″ widths with 60″+ heights. These dimensions maximize light and views while allowing flexible furniture arrangements.

Great Room Views

Large great room expanses lend themselves to wall-sized casement combinations. Stretch unobstructed views of landscapes with monster sizes like 60-72″ x 72-84″. Multiple vertical towers draw the eye up.


What custom size options exist for casements?

Most manufacturers can accommodate custom widths ranging from 14″ to 60″ and custom heights from 14″ up to 108″. This allows casements tailor fit to virtually any opening.

Do I need additional structural support for larger sizes?

oversized casements may require additional support. Consulting an installation professional ensures proper reinforcement for heavyweight units. This prevents sagging over time.

How much larger are replacement casement windows?

When replacing windows, add at least 1 inch width and height to allow adjusting into existing openings and holes.

Should I consider egress-sized casements?

If the window location serves a sleeping area, egress sizes at least 24 inches tall and 20 inches wide ensure emergency exit compliance.

Armed with an understanding of common casement window sizes and professional measurement best practices, specifying the perfect sizes becomes simple. Leverage our dimension chart when selecting the closest fit, and don’t hesitate to order custom sizes for unique needs. A few expert design tips make installing casements easy. Just remember to leave a bit extra room in your opening sizes to accommodate shims and adjustments. Follow these guidelines when planning your next casement project, and you’ll avoid surprises during installation.

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