How to Measure A Window for Replacement


When you are trying to change out an old window with a new one, it’s important to measure the opening for the new window well in advance.

When you take your measurements, be sure to measure the outside of the frame, not the opening. Some window replacement companies will come to your home and measure the window for you.

If you are measuring the window yourself, it is important to be as accurate as possible. The first thing you should have before measuring is a tape measure. Turn the tape measure over where the measurements are at the bottom. Start to make measurements for the replacement window.

This is how to measure a window for replacement. First, mark the dimensions of the window at the top. Measure down for the measurements. Second, measure irregularly shaped windows by starting with the corner. Third, measure the width. Fourth, measure the height.  

  1. Check windows for squareness;
  2. Measure the width of the opening, this is the width of the window frame;
  3. Measure the height of the opening, this is the height of the window frame;
  4. Measure the length of the window that you are looking to replace.

Check Windows for Squareness

Before buying replacement windows, ensure that the corners of your window frame are square. You will need a pencil and a measuring tape.

  1. To begin, hold your measuring tape in the top right corner of your window.  
  2. Extend the tape to the lower-left corner and record the measurement.  
  3. Next, take the same measurement from the upper left corner to the lower right corner.  
  4. Most standard windows available in the market will fit your window opening if the two readings are within ¼-inch of each other.  

Measure Window Width

When you want to know how to measure a window for a replacement, you have to learn how to measure the width of the window. It is very easy to measure the width of a window. The best way to measure window width is to measure the distance from the outer edge to the other outer edge of the window. This can be measured from the outside or the inside. 

There are two methods to measure the width of a glass window. The first is to simply measure the glass itself, not the frame. Measurement of this type is usually done by measuring the width across the outside of the glass.

The second differs in that it involves measuring the outside dimensions of the frame. This allows the dimensions of the glass window to be determined by simply taking the total width and subtracting the width of the frame. 

Measure Window Height

Next, it is important to measure the height of the window. Measure the distance from the top of the window to the bottom. 

One of the most common questions we get from people is how to measure window height. There are a few different ways to measure window height from inside or outside the room, but typically the most accurate way to do it is from the inside of the room.

To measure the height of the window, use a measuring tape and measure from the sill to the top of the window opening. Use a pencil to record the measurement. Take three measurements – on the left, center, and finally on the right side. Record the smallest of these values as the window opening height. 

There are a couple of things to keep in mind when measuring the height of the window. First, some windows have a ledge. This is some type of shelf under the window, made of wood, stone, or metal. This ledge is usually perpendicular to both the ground and the window frame. 

Secondly, there’s often some type of window seat, which is a seat that goes into the window space and is accessible from both sides of the window. This seat measures from the bottom of the window to the top of the seat.

Measure for Storm Windows

Energy efficiency is the most important thing to consider when replacing windows. Storm windows are an inexpensive way to improve your home’s energy efficiency.

Storm windows are an excellent way to help insulate your home. By whitewashing the windows during the winter, you can help maintain the temperature of your home without upping your heating bills. 

After measuring the width and height of the window in inches, make a mark in the same spot in the middle of the window and measure in this spot to find the window’s height and width. 

Repeat the process for the opposite side of the window.

The measurements should be consistent, and in some cases, maybe the same if the windows are in good condition.

There’s usually a difference in height and width due to sills and trim that were added when the windows were installed.

Measure for Window Screens

The most important part of buying window screens is measuring correctly. If you’re replacing a screen and the damaged screen is still available, then go ahead and measure its height and width. Also, if another window of the same size has a screen, you may get your measurements from there.

A typical window screen will come in two pieces. Lay one piece against the edge of the wall with one inch hanging off each side, then measure the width of the window. (For most windows, this will be 32″ wide). 

Repeat this process for the second piece. Once you have your measurements, subtract 1/2″ from both the width and the height to account for the frame, which will give you your window screen size.

Contact Us for Expert Tips on How to Measure a Window for Replacement

Once you have the measurements, it’s now time to schedule your window replacement with glass experts!

At Glass Solutions we have you covered. Our expert staff takes care of all your window replacement needs, including the measuring! Contact us now at  919-772-1007.