Best Tips on How to Measure for Replacement Windows

If you want to replace windows, you probably already know that finding suitable new windows can be truly challenging, especially if you live in an older home and want to preserve its uniqueness! At this point in your home improvement project, you’re probably wondering how to measure for replacement windows so that they fit perfectly, right?!

If so, you’re exactly where you need to be – this guide will teach you everything you need to know about window measurements. We’ve prepared a checklist with the tools you need, tips on how to measure windows based on their type, and what mistakes to avoid. Let’s make sure your new windows are a perfect fit!

Key Takeaways

Accurate window measurements are essential for a snug fit, preventing air leaks and ensuring energy efficiency and home comfort.
As a general rule, you have to measure a window’s width, height, and depth three times at three different points and then use the smallest measurement of the three.
All window types – casement, single-hung, double-hung, awning, sliding, bay, and bow windows – are generally measured in the same way.
If you need to replace many windows or windows with unique shapes, contact Magic for professional window measurements and installation.

Importance of Accurate Window Measurements

Accurate window measurements are more than just numbers on a tape measure; they’re the blueprint for a successful window replacement project. Even the highest quality windows won’t perform as expected without correct window measurements.

These precise measurements are not just about ensuring that the replacement window fits snugly into the window frame; they play a pivotal role in maintaining your new windows’ energy efficiency and overall performance. By ensuring a proper fit, you’re also enhancing home comfort and value while reducing your energy bills. Accurate measurements mean:

No drafts
No water damage
No inflated energy costs
Improved curb appeal
A comfortable, efficient living environment
Long-lasting windows that may even exceed their warranty period.

If you don’t want to measure windows yourself, book a free consultation with Magic!

How to Measure for Replacement Windows: Required Tools

Before measuring your existing window, let’s ensure your toolbox has the essentials. You’ll need:

a retractable tape measure
a notepad or your phone to write down your measurements
a ladder for hard-to-reach windows
a flashlight to make sure nothing is missed in the measurement, especially in poorly lit rooms
a small level to check if the window frames are horizontally and vertically straight
a calculator

And, of course, a bit of patience, because the process may be time-consuming!

Parts of a Window to Know Before Measuring It

In addition to the required tools, we’ve put together a list of window parts you need to know to ensure accurate results:

The window frame. The frame is a stationary window part that surrounds the sashes. It is attached to the wall.
The sashes. The sashes are located within the frame, holding the glass. They are operable.
The head jamb. This is the horizontal part at the top of the frame.
The side jambs. These are the vertical parts at the left and right sides of the frame.
The window sill. The window sill is at the bottom of the frame. It is located on the outside and is often sloped for drainage.
The blind stops. These are rectangular moldings in the assembly of a window frame nailed between the outside trim and sashes.

Step-by-Step Guide to Measuring for New Windows

A step-by-step guide ensures no detail is overlooked – from checking window squareness to recording the smallest detail. Keep in mind that each window must be measured individually, as variations in size can occur, even between windows that appear identical.

1. If Possible, Take the Measurements from the Outside

It is usually advisable to take window measurements from the outside because they’ll be more precise. You’ll likely need a ladder to reach all the windows, as well as someone to help you.

If you live in an apartment building and can’t reach the windows from the outside, you can measure them from the inside – just make sure to inform the window manufacturer about this.

2. Checking Window Squareness

Ensuring your window is square sets the stage for a successful window installation. A window that isn’t square could indicate that a standard-size replacement won’t fit properly, and a custom solution may be required.

Begin by measuring diagonally from one corner of the window frame to another – from where the head jamb meets a side jamb to where the sill meets the opposite side jamb. Repeat the process for the other corners.

If the two diagonal measurements differ by more than 1/4 inch, you’ll probably need to check for an adjusted width measurement. To check this, run the level from the top frame corner to the bottom corner. Keep it within the frame and adjust it until you notice that the plumb line and the plumb bubble are centered between the indicator window lines. Make sure to note exactly how much you’ve adjusted the level – you’ll need this in the window replacement process.

3. Measuring Window Width

You should measure the width of your window at three different points: the top, middle, and bottom of the window opening. More precisely, measure between the jambs – run the tape measure from the inner edge of one jamb to the other.

Of the three measurements you take, the smallest is the one to note as your final width. Relying on a single measurement can misguide you, as even the slightest difference can result in a window that doesn’t fit as intended.

Next, we’ll tackle the height, which is just as crucial for a perfect fit.

4. Measuring Window Height

You’ll need to check the height at three points: the left, center, and right of the window opening. Stretch your tape measure from the highest point of the sill to the top of the window opening, meaning to the window head jamb. Repeat this for the center and the other side.

Just as with the width, the smallest of the three replacement window measurements is the one to keep.

Let’s proceed to measure the depth, which is the final step that guarantees a snug window installation.

5. Measuring Window Depth

Depth may not be the first dimension that comes to mind when measuring for a replacement window, but you may need it in some cases. The depth measurement ensures that the window neither protrudes awkwardly nor recedes too far into the wall.

You’ll first need to open the window. Then, run the tape measure from the inside stops to the blind stop. The depth should measure at least 3-1/4 inches.

With these window measurements in hand, let’s see if there are any differences in measuring windows based on their type.

Measuring Double Hung, Casement, Awning, Sliding, Bow, and Bay Windows

Here’s the easy part – single-hung, double-hung, casement, awning, sliding, bay, and bow windows are all measured in the same way. Even storm windows are measured following the same steps. To make things easier for you, we’ve prepared a step-by-step guide based on the recommendations mentioned above:

Run the tape measure from where the head meets a side jamb to the bottom corner where the sill meets the other side jamb. Write down the result.
Run the tape diagonally from the opposite corner where the head meets the side jamb to the bottom corner where the sill meets the opposite jamb. Write down the result.
If you need to check for an adjusted width measurement, use the level (check above for more instructions).
Run the tape measure from the inner edge of one jamb to the inner edge of the other jamb at the top, center, and bottom.
Write down the results and circle the smallest one because that’s the one you’ll need.
Run the tape measure from the highest sill point to the window head on the left, center, and right sides.
Write down the results; circle the smallest height.
If you also need to measure the window depth, open the window.
Run the tape measure from the inside stop to the blind stop.
If it’s a picture window and you need to measure the window depth, measure the interior/exterior side and multiply it by two.
Add the thickness of the glass pane to the result.
If you’re measuring bay or bow windows, ensure to measure each window panel separately, even if they look identical. There may be slight differences that will matter in the process, especially if the windows are old.

Measuring for Window Screens

Here’s how to measure for window screens if you need to replace them:

If you still have the old screen, remove it.
Measure the screen width at the top from one corner to another. Repeat for the bottom of the screen.
Measure the screen height from one corner to another. Repeat for the other side.
If you don’t have a window screen, you’ll have to rely on the channels.
Run the tape measure from one side to the other to measure the distance between the screen channels.
Subtract 1/8 inch from the result and get the final screen width.
To measure the screen height, run the tape measure from the lip (the ridge holding the screen in place) to the window sash.
Add 1/8 inch to the result to get the final screen height.

If you have Magic screens, you don’t have to worry about these measurements. All our screens are built-in, fully retractable, and covered by our 40-year warranty. So, if one of your screens is damaged, all you’ve got to do is remove the screen cartridge and ship it to us or drop it off at one of our showrooms. We’ll solve the problem in no time!

Double-Check Your Measurements

When it comes to window measurements, the adage ‘measure twice, cut once’ could not be more pertinent. Double-checking your measurements is a golden rule in the window replacement process because it’s the safety net that catches potential errors before they turn into costly mistakes.

Reviewing your window measurements meticulously can prevent the headache of having to adjust or reorder windows. Small discrepancies can have significant repercussions, such as overworking your HVAC system or compromising your home’s thermal insulation. By taking the time to double-check every measurement, you ensure that your new windows will fit snugly and function optimally, contributing to a comfortable and energy-efficient home.

Ordering Replacement Windows

Armed with accurate measurements, you’re now ready to order your replacement windows. When you visit a window supplier, bring your detailed notes and window measurements to ensure you get the best advice and products suited to your needs.

Engaging with knowledgeable professionals can help you navigate through various window materials, styles, and installation methods, ensuring that your final choice aligns with the aesthetics of your home and its functional requirements. It’s also the perfect opportunity to discuss warranties and window installation requirements, which can impact the longevity and performance of your windows.

When placing your order, consider factors such as energy efficiency and compliance with local building codes.

If you don’t know what window manufacturer to choose, you can contact Magic for a free consultation to check out the revolutionary features of our windows – crankless and hingeless mechanisms, superior insulation, and an exponentially more durable frame material, among others!

Professional vs. DIY Measuring

When it comes to measuring for replacement windows – especially if you’re planning to replace all the windows in your home or if you have uniquely shaped windows – it’s always best to contact a professional. While taking measurements yourself can be cost-effective, hiring a professional offers the advantage of:

expertise and experience
access to specialized tools
accounting for nuances that might escape the untrained eye
faster window installation times
peace of mind with warranties covering installation-related damages.

That said, for the adept homeowner, DIY measurements can be a rewarding challenge. If you have a steady hand, a good eye for detail, and patience, you can certainly measure your windows with precision. However, if you’re hesitant about the accuracy of your DIY efforts or the complexity of the window installation, professional services are worth the investment. They can offer tips regarding various window types and ensure the installation is conducted safely, especially in challenging conditions.

This being said, if you don’t know where to start, book a consultation with Magic! Why bother taking the measurements yourself, when we offer a free in-home consultation and the window installation is included in the window price?

Common Measurement Mistakes and How to Avoid Them

Here are some common mistakes you’ll want to avoid while measuring for window replacement:

Not writing down the exact measurement. Writing, let’s say, 24.5 inches instead of 24.9 inches can yield incorrect results.
Not measuring each window. Even if the windows seem to be of the same size, it’s absolutely mandatory to measure every window you want to replace. For example, if you have two seemingly identical casement windows, there may be some minor differences in the width and height that can result in an incorrect replacement window size.
Not holding the tape measure tightly. If the windows are too large and you can’t hold the tape measure in place by yourself, ask someone to help you.
Not rounding down the measurements to the nearest 1/8 inch.
Not considering the window style. For example, if you have a double-hung window but want to install a casement replacement window, you’ll have to check if the window has enough space on the outside to open fully. Since casement windows open outwards like a door, you’ll need to use the smallest width measurement to see if it fits.
Measuring windows by yourself if they have a unique shape. If the windows you plan to replace have a unique shape, it’s best to contact an expert to measure them.

Don’t Want to Worry About Window Measurements? Contact Magic for a Quick Solution!

All in all, measuring for replacement windows can definitely be time-consuming and tricky. It can even become a slightly anxiety-inducing process because accuracy is extremely important to ensure that the replacement window is correctly sized, will last how much it’s intended to last, and will insulate your house efficiently.

If you don’t want to take the risk, Magic experts are here to help you! You can book a free in-home consultation and let us do all the work. The window installation is included in the price, so you won’t have to worry about anything!

Frequently Asked Questions

How do you measure a window for replacement?

To measure a window for replacement, you’ll need to check if the window is square. You also have to measure the width, height, and depth three times at three different points, the smallest measurement being the most accurate.

Do I need to remove the interior trim to measure for replacement windows?

In some cases, you may need to remove the interior trim to measure for a window replacement, particularly if it’s damaged or won’t fit with the new windows.

Can I use the same measurements for multiple windows of the same style?

It’s best to measure each window individually because there can be construction inconsistencies that lead to slight differences between windows of the same style. This ensures accurate measurements.

What is the most important thing to remember when measuring window openings?

When measuring the window opening, remember to take the smallest measurement for each dimension (width, height, and depth) to ensure accuracy.