Struggling with Double Hung Window Size Charts? Our Guide Will Help

Selecting the right size double hung window for your home renovation or new construction project can be downright confusing. All those numbers and dimensions in size charts seem like another language. But understanding proper double hung window sizes doesn’t have to be frustrating or complicated. Our guide will explain what all those numbers and codes mean so you can zero in on the perfect windows for your needs.

A Quick Intro to Double Hung Windows

Before diving into the intricacies of sizes and dimensions, let’s quickly review what exactly double hung windows are. Double hung windows feature two vertically sliding sash frames, meaning both the top and bottom halves of the window can be opened and closed independently. The sashes slide up and down within the main window frame by means of sash cords and pulley mechanisms.

Double hung windows are a popular choice because of their versatility, ease of operation, and ability to provide ventilation even while secured for safety. They are commonly used in bedrooms, kitchens, hallways, and other areas where adjustable fresh air circulation is desired.

Key Advantages of Double Hung Windows

  • Both sashes slide vertically to customize ventilation.
  • Available in a wide range of standard and custom sizes.
  • Require less effort to open than casement or awning windows.
  • Can provide partial through-window ventilation when locked.
  • Easy to clean from inside the home.

Demystifying Double Hung Window Size Notations

The quickest way to make sense of double hung window sizes is to understand the meaning behind the measurements. Double hung window sizes are expressed with a four-digit notation–but what do those numbers represent?

double hung window sizes chart

Quite simply, the first two digits denote the width in inches, while the second two digits represent the window’s height in inches. So a 3030 window has a width of 30 inches and a height of 30 inches. The most common sizes range from 3030 on up to larger 4068 or 4872 windows. Let’s look at a few more examples:

303030 inches wide x 30 inches high
366036 inches wide x 60 inches high
405648 inches wide x 56 inches high

Minimum and Maximum Double Hung Sizes

What are the smallest and largest double hung sizes available? Minimum widths tend to start around 24 inches wide, with 30 inches being the absolute smallest. Minimum heights also start at roughly 24 inches. On the larger end, widths up to 60 inches wide are possible, with heights reaching 72 inches or even higher with custom options.

Learn How to Properly Measure Double Hung Windows

To determine the ideal double hung windows for your home, accurate measurement of existing openings is crucial. But what exactly should you measure? There are two key dimensions to pay attention to:

1. Interior Frame Dimensions

First and foremost, measure the usable interior width and height of your current window frames. Be sure to measure from inside jamb to inside jamb for width, and inside the header down to the sill for height. A steel tape measure is the most accurate device for this. Record these frame measurements to the closest 1/8th of an inch.

2. Rough Opening Size

You also need to measure the overall rough opening size. The rough opening includes the framed structural opening in the wall surround the window. Measure the width from side stud to side stud, and the height from header to sill plate. Rough opening size determines whether a window will physically fit into the allotted frame space during installation.

Typical Double Hung Sizes for Rooms

Certain double hung sizes tend to be better suited for particular rooms and use cases. Here are some of the most popular dimensions by room:


3030, 3636, 4040


3036, 4040


2436, 3036

Hallways and Foyers

4056, 4460

Factor in ventilation needs, room sizes, and exterior wall space when selecting the best width and height combinations. Kitchens and bathrooms may prioritize humidity and ventilation over maximizing glass area for natural light, for example. Consider existing window placements as well to maintain a consistent look.

Calculating Correct Double Hung Rough Openings

As mentioned previously, rough openings are structurally framed areas in walls meant to accommodate window units. It’s imperative that you calculate rough opening sizes properly so replacement double hung windows can be inserted correctly. But how much larger should rough openings be compared to the window size?

Rough Opening Formulas

  • For width : Take your window’s width and add 1 inch.
  • For height : Take your window’s height and add 1 inch.

So for a 36 inch wide by 48 inch high double hung window, you’d need a rough opening of 37 inches wide by 49 inches high. The extra inch all around allows room to insert, fasten, insulate, and seal your new window securely within the framing.

Why Bigger Isn’t Always Better

It may be tempting to build an excessively large rough opening to give yourself more wiggle room during installation. But too much open space can make it difficult to achieve full weatherproofing around the perimeter of the window. Stick closely to the formulas above for best results.

Custom Double Hung Size Considerations

Standard double hung sizes work well for most homes. But in situations with unusually large or small openings, or complex architectural details, going custom may be wise. Some key factors to weigh with custom double hungs include:

Maximum Size Limitations

Structural integrity, material strength, and egress requirements may impose limits on just how large your custom windows can be. Consult a structural engineer for guidance.

Added Production Expenses

Custom windows typically cost more compared to standard sizes due to one-off fabrication and inability to leverage bulk discounts on materials. Expect to pay at least 15% more for custom work.

Longer Lead Times

Instead of pulling sizes straight from inventory, custom double hungs need to be made individually to order. The manufacturing process can take 4-6 weeks in some cases. Plan ahead if relying on custom windows.

Pro Tips for Installing Double Hung Windows

Once you’ve selected the ideal double hung windows for your space, proper installation is key to both appearance and performance. Here are a few professional tips as you mount them into rough openings:

Check Frames for Level and Plumb

Ensure window rough openings have frames that are perfectly plumb and level. Use shims during mounting to account for minor imperfections in the framing.

Achieve Complete Insulation

Insert backing material like fiberglass batting into any gaps around the units, especially at the header and sides. This minimizes air leaks and prevents condensation issues.

Caulk the Exterior Seam

Following installation, apply exterior-grade caulk along the seam between the vinyl window frame and the exterior building wall. Smooth evenly with a putty knife or finger.

Operating Double Hung Windows

One of the greatest benefits of double hungs is how simple they are to operate. Just follow these basic guidelines when opening, closing, and locking your windows:

Lift Sash Up Evenly in Channels

When raising or lowering top and bottom sashes, apply even pressure across each one to keep them properly aligned in the side channels. Never force!

Engage Integrated Locks

Most double hungs feature integrated locks, often spring-loaded latches, that secure the bottom sash in place for safety and ventilation. Engage locks whenever windows are occupied by children.

Tilt Inward for Easy Cleaning

Double hungs allow you to tilt sashes inward rather than remove them entirely. The tilt function provides easy access for cleaning both sides of glass panes quickly.

Caring for Your Double Hung Windows

With proper care and maintenance, quality double hung windows can deliver decades of smooth, reliable operation. Include these tasks in your regular window care regimen:

Inspect Weatherstripping

Ensure weatherstripping joints between sashes remain intact. Replace shredded or degraded seals to maintain energy efficiency and prevent air leaks.

Lubricate Sash Channels

Add small amounts of silicone spray lube to the upper and lower channels periodically. This enhances slide action and prevents sticking issues over time.

Clean Window Frames

Use a soft cloth and mild detergent in warm water for periodic cleaning of vinyl window frames. Avoid abrasive pads or harsh chemicals that could damage the finish.

When to Consider Replacing Double Hung Windows

If your double hung windows are extremely outdated or deteriorated, replacement may be your best option for improved appearance, performance, and energy savings. Some signs it’s time for new double hung windows include:

  • Loose, warped, or decaying window frames
  • Fogging or condensation between window panes
  • Visible cracks, holes, or damage to frames or glass
  • Peeling, cracked, or missing glazing and putty
  • Noticeable air leaks, drafts, or moisture intrusion

Replacing worn-out double hung windows with newer vinyl-framed models featuring insulating glass and reliable hardware can restore ease of operation while slashing heating and cooling costs.

An added benefit to new double hung windows is increased resale value of your home. Upgraded windows appeal greatly to prospective home buyers. Take before and after photos to showcase your window replacement project.

We hope this overview has helped eliminate any confusion surrounding double hung window size selection, measurement, installation, and maintenance. Confidently navigate the numbers and dimensions with this knowledge. Let our guide set you on the path to double hung window success!

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