How to Measure Your Windows for Storm Windows

Get accurate measurements for custom storm windows. Follow our step-by-step guide to ensure a perfect fit and easy installation for every window in your home.

Tools You'll Need

Measuring your windows accurately is crucial for a perfect fit. Here's what you'll need:

• 1
  Metal Measuring Tape:At least 6 feet long for accuracy
• 2
  Step Ladder:For measuring high windows safely
• 3
  Notebook & Pencil:To record measurements for each window
• 4
  Assistant (Optional):Helpful for measuring hard-to-reach areas

Step-by-Step Measuring Guide

Follow these steps carefully for each window. Remember to measure the opening, not the existing window.

Step 1: Prepare Your Window

• Remove any existing storm windows or screens from the window you're measuring.
• Clean the window frame and ensure it's free of debris.
• Close the interior window completely. If your window has movable sashes, position them as they would be when closed.
• Important: Always measure the window opening (jamb), not the glass or existing window frame. The storm window will mount to the exterior of your current window.

Step 2: Measure Width (Left to Right)

• Measure the width at the top, middle, and bottom of the window opening.
• Use the smallest measurement to ensure your storm window will fit.
• Place your tape measure at the left jamb and extend it to the right jamb.
• Measure in three places and record the smallest width.
• Round down: If your measurement is 35 ⅝", round down to 35 ½" for ordering.

Step 3: Measure Height (Top to Bottom)

• Measure the height at the left, center, and right sides of the window opening.
• Again, use the smallest measurement.
• Start from the top jamb and measure down to the bottom jamb.
• Take measurements at three points and record the smallest height.
• Round down: If your measurement is 59 ⅞", round down to 59 ¾" for ordering.

Step 4: Record Your Measurements

• Write down the measurements for each window, including the room location and window number.
• Example: "Living Room Window #1: Width 35½", Height 59¾""
• Keep your measurement sheet organized and double-check all entries before ordering.

Common Measuring Mistakes to Avoid

These common errors can lead to ill-fitting storm windows. Make sure to avoid them.

• Measuring the Glass:Storm windows mount to the exterior frame, not the glass. Always measure the jamb opening.
• Using Average Measurements:Windows aren't always perfectly square. Always take multiple measurements and use the smallest.
• Not Rounding Down:Storm windows need clearance to fit properly. Always round down to the nearest ⅛ inch.
• Measuring with Window Open:Close the interior window completely before measuring. Storm windows mount to the jamb.

Special Measuring Situations