How to Measure Windows for Replacement
Getting the right Window size will save you time and money. This article explains, in easy steps, how to measure windows for replacement.
  • When you order Windows from a Manufacturer or a Reseller, your measurements will be for estimates only.
  • The sizes you measure are critical if you use your measurements to order windows from a Retailer or Online for a DIY project.

How to Measure Windows for Replacement:

Measure Screens for Replacement


1. Measuring the Window Opening Size: Width x Height


All Measurements are from the Inside of the house.
  1. To Measure the Width: you will need to measure the distance from Side to Side (Jamb to Jamb).
  2. To Measure the Height: you will measure the Distance from Top to Bottom (Head to Sill).
  3. The starting point for measuring is where you see the window touching the wall. You will find these points on the Left, Right, Top, and Bottom of each window you are replacing.
  4. The Points where the window touches the wall on the left and right are the Jambs. You will measure the Width by measuring Jamb to Jamb (Left Jamb to Right Jamb).
  5. The Point where the window touches the Top is the Head, and the Bottom is the Sill. You will measure the Height by measuring the distance between the Top and Bottom points (Head to Sill).
  6. Measuring the Width: measure the distance between the Left and Right points at the Top, Bottom, and Middle (between the Top & Bottom) of the window. Please write the measurements down.
  7. Measuring the Height: measure the distance between the Top and Bottom at the left and Right Sides and the Center of the window. Please write the measurements down.
  8. Select the smallest of the 3 Widths and Heights you measured as your Width and Height to order or use to get an estimate. The smallest size measured is the safest size to order. Installers can always build & shim around an undersized window, but it is much harder to deal with an oversized window. The smallest size also safeguards against Windows that are not Square or have become misshapen over time.
  9. The Windows will be smaller (by a 1/4 or 1/2 an Inch) than the sizes you measured.

2. Measuring the Window Depth

To order windows for a Do It Yourself Window Replacement Project, measuring the Depth of the Existing window is essential.
Steps To Measure the Depth of the Wall and the Window: 
  1. Open The Window so that you can access the outside of it. 
  2. Measure the distance between the Inside and the Outside of the Window. That measurement is the Frame Depth. Please write it down, as it will be helpful to get Estimates and choose the right window. 
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