How to Measure for Custom Window Screens: A Step-by-Step Guide

Ever tried to order a custom window screen only to find it doesn’t fit when it arrives? You’re not alone. Getting the measurements right is the difference between a perfect fit and a frustrating remake. The good news? Measuring for custom window screens is simpler than you might think—once you know what to measure and where.

In this guide, I’ll walk you through everything you need to measure your windows accurately, whether you have single hung, double hung, casement, or sliding windows. Grab a tape measure, and let’s get started!

Why Accurate Measurement Matters

You might wonder: can’t I just measure once and be done with it? Well, here’s the thing—window frames are rarely perfectly square. Over time, homes settle, frames warp slightly, and what looks like a 36-inch opening might actually measure 35-7/8 at the top and 36-1/16 at the bottom.

Ordering a screen that’s too large means it won’t sit properly in the frame track. One that’s too small will have gaps, letting in bugs, dust, and reducing your window’s energy efficiency. Custom window screens are made to your exact specifications, so the measurements you provide are crucial to getting a perfect fit.

Taking a few extra minutes to measure correctly the first time saves you from the hassle of returns, remakes, and delays. And honestly, it’s not hard once you know the process.

Tools You’ll Need

Before you start, gather these simple tools:

• A flexible measuring tape – Rigid rulers won’t work well for measuring inside window frames
• A notepad and pen – Write down measurements as you go
• A friend (optional but helpful) – Someone to hold the tape steady while you read the numbers
• A step stool or ladder – For reaching higher windows safely

That’s it! No special tools required.

Understanding Window Screen Measurements

Before we dive into the step-by-step process, let’s clarify what we mean by “width” and “height” in window screen terms:

• Width – The horizontal measurement from left to right
• Height – The vertical measurement from top to bottom

For window screens, you typically measure the frame opening where the screen will sit. This is different from measuring the glass itself (which would be the “glass size” or “daylight opening”).

Step-by-Step Measurement Guide

Step 1: Remove the Old Screen (If Applicable)

If you’re replacing an existing screen, remove it carefully from the window frame. This gives you a clear view of the channel where the new screen will sit. Look for any clips, tabs, or hardware that hold the screen in place—you’ll want to reinstall your new screen the same way.

Step 2: Measure the Width

Here’s where many people go wrong—they measure in just one place. Instead:

1. Measure across the top of the window frame opening from left to right
2. Measure across the middle of the opening
3. Measure across the bottom of the opening

Record all three measurements. When ordering, use the smallest of the three numbers. This ensures your screen won’t be too wide for any part of the opening.

Step 3: Measure the Height

Now measure vertically:

1. Measure from the top of the frame opening to the bottom on the left side
2. Measure the same way on the right side
3. Measure one more time in the center

Again, use the smallest measurement for your order. This accounts for any slight irregularities in the frame.

Step 4: Determine Screen Type

Not sure whether you need a full screen or half screen? Here’s the quick guide:

• Full screen – Covers the entire window opening; ideal for windows that open from the bottom (like single hung) or that you want complete protection
• Half screen – Covers only the top portion; common for double hung windows where only the bottom sash moves and needs ventilation

For most replacement situations, a full screen is the safer choice unless you have a specific reason for a half screen.

Step 5: Note Any Special Considerations

Some windows have unique features that affect screen fit:

• Offset tabs – Some window frames have tabs that hold the screen at an angle; measure accordingly
• Channel depth – Standard screens fit into channels about 5/16 inch deep; measure yours to confirm
• Pull tabs or handles – Note their location so your new screen doesn’t interfere

Measuring Different Window Types

Single Hung Windows

Single hung windows have a fixed top sash and a movable bottom sash. Since the bottom sash moves up for ventilation, you’ll want a full screen that covers the entire opening. Follow the standard measurement process: three width measurements (use smallest), three height measurements (use smallest).

Double Hung Windows

Double hung windows have both top and bottom sashes that can move. Many homeowners choose half screens for these windows since typically only the bottom sash is raised. If you want flexibility to raise either sash, order a full screen. Measure the same way as single hung windows.

Casement Windows

Casement windows have a crank mechanism that pushes the sash outward. They typically use full screens. The measurement process is the same, but pay extra attention to the channel depth—casement frames sometimes have deeper channels. Also note which side the crank handle is on, as this may affect screen hardware placement.

Sliding Windows

Horizontal sliding windows move side to side. You’ll need a full screen that covers the entire sliding panel’s opening. Measure width and height as usual, using the smallest measurements. If your slider has a fixed and moving panel, make sure you measure the opening that needs screening (usually the moving panel’s area).

Common Measurement Mistakes to Avoid

Let’s save you some headaches! Here are the most frequent errors people make when measuring for custom window screens:

Mistake #1: Measuring the Glass Instead of the Frame

The glass measurement is smaller than the frame opening. Always measure the actual frame where the screen will sit, not the visible glass area.

Mistake #2: Rounding to the Nearest Inch

Windows are rarely exact inches. Measure to the nearest 1/16 inch for accuracy. That extra precision matters when you’re ordering custom sizing.

Mistake #3: Using Only One Measurement

As mentioned earlier, frames aren’t perfectly square. One measurement can be deceiving. Always take three of each (top, middle, bottom) and use the smallest.

Mistake #4: Forgetting to Account for Screen Hardware

The screen needs room to fit into the frame channels. When you order custom window screens, the manufacturer will typically account for this, but it’s good to understand that the “screen size” is slightly smaller than the “frame opening” to allow for proper insertion.

Mistake #5: Not Writing Down Measurements Immediately

It’s easy to forget a number, especially when moving between windows. Write everything down as you measure—label each window clearly (e.g., “Living Room Left,” “Kitchen Window 1”).

Pro Tips for Perfect Measurements

• Measure twice, order once. It sounds cliché, but it’s solid advice. Double-check all your numbers before submitting your order.
• Have someone help with large windows. A helper keeps the tape straighter and more accurate for wide or tall windows.
• Use a metal tape measure. Cloth tapes can stretch over time, giving inaccurate readings.
• Document with photos. Take pictures of each window and your measurements. This helps if you need to verify later.
• Keep a measurement card in your wallet. Once you have accurate measurements, write them down somewhere permanent. You’ll thank yourself when it’s time to order again.
• Consider seasonal changes. In very humid or dry climates, wood frames can expand or contract slightly. If your home experiences extreme conditions, mention this to the screen manufacturer.

When to Order Custom vs. Standard Sizes

Standard window screen sizes work for many common window dimensions. But here’s when custom is the better choice:

Order Custom Window Screens When:

• Your window dimensions don’t match standard sizes (most aren’t 24″x36″!)
• You have non-standard or custom-built windows
• You need a specific mesh type (pet screen, solar screen, fine mesh for allergies)
• Your window frames are older and may have unique channel depths
• You want a precise, professional fit rather than a “close enough” standard size

Standard Sizes May Work When:

• You have builder-grade windows with very common dimensions
• You’re in a hurry and can accept a less-than-perfect fit
• The cost difference matters more than perfect aesthetics

For most homeowners, custom window screens are worth the modest investment. They fit better, look better, and provide better protection against pests and debris.

Frequently Asked Questions

Do I need to account for the thickness of my window frame when measuring?

For most custom window screen orders, you simply need to provide the frame opening dimensions (width and height of the space where the screen sits). The screen manufacturer will determine the appropriate screen size based on standard channel depths. However, if you have unusually shallow or deep channels (older homes sometimes do), note this when ordering.

Should I round up my measurements to be safe?

No! This is a common misconception. Always use the smallest of your three measurements, and provide that exact number. Rounding up results in a screen that’s too large and won’t fit properly. The screen needs to be slightly smaller than the opening to sit in the frame channels.

What if my window frame is not perfectly square?

This is normal! Most window frames have some degree of irregularity. That’s why we recommend taking three measurements for each dimension and using the smallest. This ensures your screen will fit even in the most challenging part of the opening.

How do I measure for a half screen vs. a full screen?

For a full screen, measure the entire frame opening as described above. For a half screen (common on double hung windows), measure the full opening dimensions but specify “half screen” when ordering. The manufacturer will create a screen that covers approximately the bottom half. Half screens are typically half the height of the full opening, though you can request a specific height if needed.

What if I’m between standard sizes?

That’s exactly why custom window screens exist! If you’re between standard sizes (say, your window is 35-3/4″ wide but standards jump from 35″ to 36″), custom sizing ensures you get a screen that fits perfectly. Don’t try to “make do” with a close standard size—gaps around the edges defeat the purpose of having a screen.

Ready to Order Your Custom Window Screens?

Now that you know how to measure for custom window screens, you’re well-prepared to get the perfect fit. Accurate measurements mean no gaps, no drafts, no bugs sneaking through—just clean, functional screens that look great and protect your home.

When you’re ready to order, check out our custom window screens page. We offer a range of mesh options, sizes, and finishes to match your specific needs. Have questions about your measurements or options? Our team is happy to help you get it right the first time.

Happy measuring, and enjoy your perfectly fitted custom window screens!