Accurate measurements are the foundation of a successful window replacement. Order a window that's even a quarter-inch too large or too small, and you're looking at delays, extra costs, and a compromised installation. This step-by-step guide walks you through how to measure your windows correctly — whether you're getting quotes from contractors or ordering windows yourself.
Important note: These measurements are for getting accurate quotes and understanding your project scope. Your installer will take their own precise measurements before ordering. Never order windows based solely on your own measurements without professional verification.
- A steel tape measure (not a fabric tape)
- A pencil and notepad
- A helper (for larger windows)
- A ladder if measuring from outside
Measure the width of the window opening from the inside of your home. Place your tape measure from the left interior side jamb (the vertical frame piece) to the right interior side jamb. Take three measurements: one near the top, one in the middle, and one near the bottom. Record the smallest measurement — this is your rough opening width.
Measure the height from the sill (the flat horizontal piece at the bottom of the window) to the head jamb (the horizontal piece at the top). Take three measurements: left side, center, and right side. Again, record the smallest measurement.
Measure diagonally from corner to corner in both directions. If the two diagonal measurements are equal (or within 1/8 inch of each other), your opening is square. If they differ by more than 1/4 inch, the opening is out of square and your installer will need to account for this — it may affect the type of installation required.
Measure the depth of the window frame from the interior stop (the small strip of wood that holds the sash in place) to the exterior stop. This measurement determines whether a standard replacement window will fit in your frame or whether you need a custom depth. Most replacement windows are designed to fit standard 3 1/4" to 4 9/16" frame depths.
Insert replacement (also called pocket replacement) involves installing a new window unit inside the existing frame, leaving the exterior trim and siding intact. This is the most common and cost-effective approach when the existing frame is in good condition. The new window is sized slightly smaller than the opening to fit inside the existing frame.
Full-frame replacement removes the entire window assembly — frame, sill, and all — down to the rough opening. This is necessary when the existing frame is rotted, damaged, or when you want to change the window size. Full-frame replacement costs more but gives you a completely fresh installation.
Let Us Handle the Measurements
When you schedule a free estimate with Jonesboro Window Pros, our installer will take precise measurements of every window in your home — at no charge. We guarantee our measurements are accurate and that every window we install will fit perfectly.
Call (870) 259-5628