How to Measure Your Windows for Replacement - K & J Windows, LLC

How to Measure Your Windows for Replacement

Posted by in Window Installation and Window Replacement

How to Measure Your Windows for ReplacementWhen it’s time to replace your home’s old, drafty windows with new, energy-efficient models, getting accurate measurements is one of the most important steps. Knowing the precise width, height, and depth of your existing windows ensures that your new windows will fit perfectly with minimal adjustments or gaps. Follow this guide to learn how to measure windows like a pro so your window replacement project goes smoothly.

Why Proper Measurement Matters

Measuring window openings accurately before ordering replacement windows is crucial for several reasons:

  •         Improperly sized windows may not fit into the existing window frame or opening. This could require additional work to modify the opening or return the windows.
  •         Gaps between the new windows and existing framing can allow air or water to penetrate and decrease energy efficiency.
  •         Inaccurate measurements may result in the need to re-order windows, causing project delays and added costs.
  •         Taking accurate measurements the first time prevents having to redo work, so it saves you time and hassle.
  •         Precise measurements allow the window installer to prepare everything needed for a smooth installation.
  •         Correct measurement helps the manufacturer build your custom windows to suit each unique window opening.

Taking the time to measure correctly the first time prevents headaches down the road!

Tools You’ll Need

Measuring window openings precisely is easy with just a few basic tools:

Tape Measure

How to Measure Your Windows for ReplacementA metal retractable tape measure is essential for accurately measuring linear dimensions. Choose one at least 25 feet long to easily measure large openings. Ensure the tape measure can extend and retract smoothly and holds its place when extended.

Pencil and Paper

Have a pencil and paper handy to record the measurements for each window opening as you work. Pencil allows errors to be easily erased. Organize your notes by labeling each window, e.g. “Bedroom window 1.”


A sturdy ladder may be needed to access measurement points on tall windows. Use caution when working at height.

Laser Distance Measure

For hard-to-reach spots, consider using a laser distance measurer for precise single-point measurements. Just be sure to double check the laser readings manually.

Measuring Window Width and Height

The two most important measurements are the width and height of your current window openings. Measure from inside the house for inside mount windows, or outside for outside mount windows.

Inside Mount Windows

If your existing window frames will remain in place, measure between them for the inside width and height. Measure across the inside of the frames in 3 spots – top, middle, and bottom – and record the smallest width. Do the same for the height, measuring in 3 places on each side. This ensures your new windows are slightly smaller than the openings.

Outside Mount Windows

For windows that will mount completely inside the window opening, measure the opening itself. Measure width across the top, middle, and bottom, then height on both sides. Record the largest measurements.

How to Measure Your Windows for ReplacementTriple Check

To ensure accuracy, measure each window width and height three times. Multiple measurements help identify any human errors. Take notes each time and compare for consistency.

Measuring Window Depth

The depth of your window openings is also needed to ensure the window box extends properly beyond the exterior wall. This varies by window type:

Flush Mount Windows

Flush mount windows sit directly against the interior wall with no window box. Simply measure the wall thickness as the depth. Often this is 4 1⁄2 or 6 1⁄2 inches.

Projected or Box Windows

Projected or box windows have an angled extension that protrudes beyond the wall. For these, measure from the interior wall to the exterior edge of the window box.

Be sure to measure depth at both the top and bottom of the window and use the greater value. Account for any sloping or irregularities.

Other Measurements to Consider

Some additional measurements may be needed for certain window types or features:

Frame Thickness

If keeping existing frames, measure the frame thickness from the interior wall to the inside edge. This ensures proper window clearance.

Moulding and Trim

Measure any interior or exterior mouldings or trim that may impact window clearance. Include baseboard trim and window sill thickness.

Window Hardware

Note measurements for existing hardware like hand cranks, latches or locks that will be replaced or reused.

Window Condition

Inspect windows for any damage, rot or defects that may impact installation and note this for the installer.

It’s always better to have too many measurements than too few, so don’t miss any small details that could affect your replacement windows.

Snap Photos to Supplement Measurements

Taking photos of each measured window from both interior and exterior angles is highly recommended. This provides useful visual references for the window installers. Photos can clarify any unclear measurement notes too.

Contact the Experts for Help

Window measurement doesn’t need to be a hassle or guesswork. The team at K&J Windows has years of experience measuring windows for flawless installation. If you need help determining the perfect custom windows for your Phoenix home, contact us today to schedule your free in-home consultation! We provide precise measurements and expert guidance so you get windows that maximize beauty, comfort and value.

Quality Installation

In addition to precision measurements, proper window installation is also key to getting a tight seal and long-term performance from your new windows. K&J Windows employs fully licensed, bonded, and insured installation experts who follow manufacturer specifications and industry best practices. We also handle any necessary permits or paperwork.

How to Measure Your Windows for ReplacementEnergy Efficient Options

Replacing outdated windows with energy efficient models is one of the smartest upgrades you can make. New windows prevent costly air leaks and keep your home’s temperature stable. K&J Windows offers high performance glass, weatherstripping, and other options to customize your windows for maximum energy savings.

Enhance Curb Appeal and Comfort

Along with saving on energy bills, new replacement windows also boost your home’s beauty and comfort. We help select customized windows to match your home’s style and layout. Added features like UV protection, noise reduction, and security enhancements also let you tailor your new windows for ideal comfort.

 Refresh and enhance your home today with new energy efficient windows expertly installed by the pros at K&J Windows!

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