How to Measure for Replacement Windows

Two professional workers in uniform using tape measure while measuring window

Most homeowners will need to invest in new windows at some point in the life of their homeownership. Whether you just moved into an older home and replacing the windows is your first order of business, or you’ve lived in your house for many years and have started to see higher-than-average energy bills, a window replacement project can yield great benefits. Better curb appeal, a more energy-efficient home, and windows that are easier to maintain are just a few of them. But where should you even begin when it comes to this project?

You could start with the windows themselves. Take a look at the windows in your home and decide which ones need to be replaced. Is it all of them? Or perhaps you’re looking to replace just a few of your windows right now. You’ll want to record accurate measurements of your windows so you understand exactly the types of windows you need. Here’s how to do that:

Step 1: Make Sure Your Windows Are Square

In order to determine the type of window you need (such as a replacement window or new-construction window), you’ll need to find out if all four corners of the frame are at 90° angles. To do this, measure the window diagonally starting at the upper left corner (where the horizontal and vertical trim boards meet) to the inside of the lower right corner. Do the same for the other side of the window. If the measurements are within ¼-inch of each other, a replacement window can be used.

Step 2: Record the width of the window.

Now, it’s time to figure out your window’s width. You’ll want to measure in three places:

  • At the bottom of the window from the lowest point of the window jamb (if possible, push the window up during this measurement)
  • In the middle of the window from jamb to jamb (with the window still up)
  • At the top of the window from jamb to jamb (with the window closed)

Record all three measurements and highlight the shortest one.

Step 3: Record the height of the window

Recording the window height is similar to that of the width, but instead of measuring from window jamb to window jamb, you will measure from the head jamb (the top horizontal board above the window) to the bottom sill (the horizontal board where the bottom of the window sash sits when the window is closed). It’s important to note that the bottom sill is not the windowsill. You’ll have to open the window to access the bottom sill.

Record a measurement on the far left of the window, the middle of the window, and the far right of the window. Highlight the shortest measurement.

Step 4: Find Your Ideal Window Size

To find your ideal window size, use the highlighted measurement (the shortest measurement you recorded) and round it down to the nearest 1/8 of an inch. This is the final number that you’ll use to order new replacement windows.

An Easier Option to Measuring Your Windows

There is always a possibility of mistakes happening when measuring your windows, especially if you’re a novice at this process. An easier option? Letting the pros at Reborn Home Solutions take care of all the measurements you need. We are a leading window contractor that can expertly measure your windows and provide you with meticulous window installation service. You won’t have to worry about a thing when you turn to us for new windows! We’ll provide you with The Ultimate Remodeling Experience® and you can sit back and relax.

Contact Reborn Home Solutions today to learn more about our window replacement service. We’ll be glad to schedule a complimentary consultation at your convenience.

Visit a Showroom

Anaheim Showroom


2981 E. La Palma Ave.
Anaheim, CA 92806

Showroom Hours

Lake Forest Showroom


23626 El Toro Rd. Suite B
Lake Forest, CA 92630

Showroom Hours

Torrance Showroom


24667 Crenshaw Blvd. Suite A
Torrance, CA 90505

Showroom Hours

San Diego Showroom


6615 Flanders Drive, Suite A
San Diego, CA 92121

Showroom Hours

Livermore Showroom


1306 Stealth St., Ste. A
Livermore, CA 94551

Showroom Hours
Please call 855-945-1348 to schedule an appointment.

Las Vegas Showroom


5895 W. Wigwam
Las Vegas, NV 89139

Showroom Hours
Please call 855-945-1348 to schedule an appointment.

Phoenix Showroom

4100 S. 38th Street, Suite 100
Phoenix, AZ 85040

Showroom Hours

Corporate Office


5515 E. La Palma Ave
Anaheim, CA 92807

Corporate Office Hours

Start Your Project With Reborn Today
There’s no time like the present to give yourself the gift of a Reborn home.