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How to Measure Your Double Glazing


Before you can select your doors and windows, it is important to know how to measure your double glazing. This is to ensure that your fittings are ordered in the right size. Incorrect measurements lead to doors and windows that don’t fit in the apertures. Even if they do, it might result in improper installation and lead to you paying an inaccurate double glazing cost.

As a result, your double glazing will not perform as expected. What’s more, it is even likely to need repairs sooner rather than later. If you are unsure about measuring your double glazing, you can consult a professional.

If you call us at 0800 954 8085, we’d be happy to advice you on how to measure your double glazing. We’ll even recommend FENSA or CERTASS accredited local installers who might be able to help you. However, our double glazing quote includes a full technical assessment by a double glazing surveyor. He will be happy to verify your measurements for you.


Things to Remember When You Measure Your Double Glazing


Measure from Outside


As a standard, always measure the apertures of your doors and windows from the outside. This is because doors and windows are usually fitted from the outside in. There is a chance that there is a variation in the sizes of the aperture on the inner and outer edges. In this case, the double glazing needs to fit in from the outside.


Measure Brick-to-Brick


When you measure your double glazing, always measure from brick to brick. That is, do not measure the frames or from the edge to edge of the sash or panel. The measurement should be of the aperture or opening. Measurements of the current door or window will result in incorrect sizes being ordered.


Three Measurements


In order to get a more accurate measure of your double glazing, always take three different sets of measurements. When measuring the width, measure it at the top, middle, and bottom of the aperture. Similarly, when you measure your double glazing for height, get the left, middle and right measurements. Use the average of the three figures, and subtract 10mm from this figure for fitting allowances.




When you measure your double glazing, always include the width and height of the frame, the cill, and the measurements of frame extenders or additional fittings. This will give your double glazing supplier an accurate estimate of the measurements.


Window Height From Floor


When you are measuring for window sizes, always check the height of the window from the floor. To measure this, you need to start from the bottom of the cill and down to the floor. If the distance is less than 80cm, or 800mm, you will need reinforced glass for your window.


Bay and Bow Window Measurements


Bow and Bay windows are measured slightly differently from other windows. You will need the measurements of all panels, and the depth of projection. The height for these panels will be the same, but the width of each needs to be measured. When measuring for these windows, you will need to measure your double glazing both internally and externally.


Why Is Knowing How to Measure Your Double Glazing Important


Knowing how to measure your double glazing is a very important first step in replacing your double glazing. Correct measurements can save you money and time. They will also help prevent shoddy installation and poor performance.

If you measure your double glazing improperly, chances are you will get double glazing units that don’t fit your apertures. Since you have already bought and paid for them, it’s a loss for you. You will need to reorder them with the proper measurements. As a result, you would have wasted time.

Additionally, if you had already booked your installers, you’d have to reschedule. You might or might not get your deposit back in such a case. What’s more, the installer’s time as well as yours is wasted.

This is one of the main reasons why we offer a full technical survey included in our quote. The surveyor will double-check your figures after you measure your double glazing. As a result, when you place your order, you know it’s going to be perfect for your home.


Get An Honest Quote After You Measure Your Double Glazing


Once you know how to measure your double glazing, you will need to get quotes for replacement double glazing online. You’ll be happy to know that our team does not believe in aggressive sales pitches. Therefore, when you get a quote from us, it is completely free with no obligations.

Give us a call at 0800 954 8085 to get your quote, or for help in learning how to measure your double glazing. We’ll be happy to answer any questions you may have. Alternatively, you can contact us online.

You can even get an instant quote using our online quoting engine. Just feed in your measurements and requirements and it will generate your quote in minutes!

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