Man standing on ladder measuring top window of brick home
Replacing windows is a significant investment that can greatly enhance your home’s comfort, energy efficiency, and aesthetics. However, accurate measurements are vital for a successful window replacement project.

Whether you’re replacing a single window or undertaking a larger project, understanding the measurement process is crucial to ensure a seamless fit and optimal performance.


Measure Window Width

Accurately measuring the width of your windows is important for selecting the right replacements. Improper width measurements can result in ill-fitting windows that compromise the functionality and look of your home.

To measure the window width effectively, follow these steps:

  1. Using a tape measure, take three measurements of the window’s rough opening width; one at the top, one in the middle, and one at the bottom from the side window jamb.
  2. Make a note of the smallest of these measurements.
  3. Use this smallest measurement as the main width measurement when shopping for a replacement window.

Measure Window Height

An incorrect height measurement can lead to windows that are too tall or too short, compromising their overall appearance and functionality. List the window’s height measurement after the width:

  1. Use a tape measure to measure the window’s rough opening height from the window sill to the head jamb. Do this three times, at the window’s left, middle, and right.
  2. Make a note of the smallest of these measurements.
  3. When shopping for a replacement window, use this smallest height measurement as the main height measurement.

Measure Window Depth

Determining the window depth is important for selecting the right replacement windows. Proper depth measurement ensures that the new windows will fit within the existing window frames without any issues.

Follow these steps to measure window depth accurately:

  1. Use a tape measure to measure from the outside of the frame to the inside of the frame.
  2. Repeat this at multiple points around the window.
  3. Make a note of the smallest of these measurements.
  4. When buying a replacement window, use the smallest measurement as the main depth measurement.

For windows that won’t open, measure the depth on each side of the glass. Add those two measurements to the thickness of the glass itself. In most cases, glass is usually 1/8 inch or 3 mm thick.

Measuring a Bow or Bay Window

Taking measurements for a bow or bay window is more complex than measuring for a standard rectangular window. Width and height measurements are needed for each window panel and the entire window area.

  1. With a tape measure, measure the width of each panel at the center from jamb to jamb or trim to trim.
  2. Note the center window width separately.
  3. Measure the height of the bay window at the center, from trim to trim.

This information will give you a solid foundation when pricing options and determining your budget.

Additional Considerations for Window Replacement

In addition to the essential dimensions, there are a few factors to consider when preparing for window replacements:

  • Frame condition: Ensure that the window frames are in good shape, free from rot or damage, as they provide the structural support for the new windows.
  • Check if the window is square: Square means that all four corners of the window opening measure at 90-degree angles. To conduct a square check, use a tape measure to measure the opening diagonally from top right to bottom left and top left to bottom right. If the two measurements are within a quarter inch of each other, the opening is square. If not, contact a professional for a new frame.
  • Window level: Place a level on the window sill. If the bubble rests between the indicator lines, the window is level.
  • Window plumb: Place a level against the face of the side jamb. If the bubble rests between the indicator lines, the window is plumb.
  • Window variations: Account for adjustments needed for custom windows, screens, storm windows, or double-hung windows. Following the same measurement process, you’ll need to measure each pane for double-hung windows.

Top-Quality Replacement Windows

Installation of replacement windows can be complex. To ensure you get the best return on your investment, consider a professional who understands those complexities and can handle anything unexpected. The installation team at Zen Windows St. Louis has extensive experience and comprehensive training to handle all your window replacement needs.

You can expect high-quality materials, exceptional customer service, and a simple, no-hassle process for your window replacement project.

Get the best professional window replacements in the St. Louis area today. Call Zen Windows at (314) 399-0856.