How To Measure For Replacement Windows

If you’re looking at installing replacement windows yourself then understanding how to measure for replacement windows correctly is essential, if you don’t get the measurements correct you could end up ordering a window which is completely the wrong size for your window opening and end up wasting a lot of your hard-earned money.

When you’re measuring the window it’s important that you get the measurements as close to the rough opening of the window as possible so that your window has the best chance of fitting without any further issues. If you’re not 100% sure on the process then it’s usually best to get an approved window installer to measure and install replacement windows for you.

The measurements you take will differ depending on how much of the window you are replacing. If you’re replacing the entire window and frame then the measurements are usually taken from the dry-wall edges but if you’re replacing only the window and leaving the frame in place then the measurement will be taken from the daylight opening on one edge of the frame to the other.How To Measure For Replacement Windows

How To Measure For Replacement Windows

Step 1 – Measure The Width Of The Window

Before you do any other measuring you should take the width of the window first, remember that for situations where you’re not replacing anything other than the window, you will measure from the one inner edge of the window jamb to the other. This measurement has to be taken at three points along the window frame, once at the top, once at the middle and once at the bottom, just as the diagram shows below. You should now have 3 separate measurements written down.

Step 2 – Measure The Height Of The Window

Next, you will need to repeat this process by measuring the height in the window from the window sill to the window head. Again, you will measure once on the left, once in the middle and once on the right, thus giving you 3 separate measurements to write down.

Step 3 – Using The Smallest Of These Measurements

Once you have your 6 measurements, 3 from the horizontal measurement and 3 from the top measurement, you need to take the smallest of each aspect. The reason for this is that you may have 3 slightly different measurements for the both the horizontal and the vertical aspects of the window, going with the largest may result in you purchase a window which is too big, in which case fitting them becomes a nightmare. However, smaller windows can also be padded out to allow for any gaps in the installation.

Quick Reference For Replacement Window Measurement

Table 1 below gives you a brief summary of the measurements you need to take, if may be worth printing this page out for future reference (print icon found at the top of this page) when it comes to measuring your windows.

Table 1: Quick Measurement Sheet For Window Replacement

Window Width Measurements (inches) Window Height Measurements
Width At The Top ……………. inches Height At The Far Left ……………. inches
Width At The Middle ……………. inches Height At The Middle ……………. inches
Width At The Bottom ……………. inches Height At The Far Right ……………. inches
Smallest Width Measurement ……………. inches Smallest Height Measurement ……………. inches

Overall, measuring your windows is the easy part but it’s the part that needs to be done right as those measurements will determine how the rest of the process goes.

If you’re not confident at providing accurate measurements then you can get this free as part of the replacement window quotation process and in all honesty, we recommend that you do.

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