how to calculate glass measurement

How to Calculate Glass Measurement | Ideas from Professionals

Getting the size of glass so you can place an order for your window or door glass can be very demanding. And most often, you have to know the measurement of glass so you can get the right fit for what you intend to use it for, be it for your window, door or shelves. This article will discuss how to calculate glass measurement, taking into consideration, glass thickness, glass weight, and other instruments you can use to measure glass. When measuring your glass, you should keep in mind the tight size which will determine If the new sheet of glass you are ordering will fit into the existing glass frame. Order a large size and it will not fit into the hole.

On the other way around, order a small size and you have to struggle to fit the glass in, but definitely, it will not fit into the hole. So, what must you do to get the right size of glass that fits? Read along to get the answer to that. To get it right, you must not only measure according to the hole, but you also have to take into the calculation, the dimensions the glass will recess into, which is called the “tight size.”

What is the measurement of a glass?

Measurement of a class is the calculation necessary to determine the size of the glass, taking into account its weight, thickness, length, and width, amongst others. A glass measurement is done by calculating the glass weight and also the square footage. The formula is given below.

First, to even begin the calculation of a glass measurement, you need to determine the area of the glass. The calculation for the area of glass formula is:

Area of glass = Area of cuboid 



            =4250 cm2

Thus, the area of glass is 4250 cm2.

For the weight of a glass:

Glass weight in KG = Area of glass M2 (length x width) x thickness of the glass x 2.5KG.

The calculation may seem perplexing to someone who is not good at mathematics. Hence, there is a glass weight calculator app online that you can use to arrive at the answer you seek. One of them is available at Glass Calculator. You can also search online if you find the website complicated, or download a glass weight calculator app.

To calculate the square footage of glass, the formula is:

Measurement of square footage

Measure the length of the glass and jot the result down somewhere. Then with the same tape, measure the width of the glass. All should be measured in inches. The result you get from the two should be multiplied together. Then divide the result by 144. The result you get from the division is the square footage of the glass.

Width x length = square inch ÷ 144 = square feet.

Table showing the size of a sheet of glass

Sheet glass size comes in varied thicknesses, however, the most commonly used for window glass are 3/32- and 1/8 inch according to Construction Manuals. Thicknesses may be single-strength (SS) or Double Strength (DS) based on their ability to withstand the design. A table is given below:

THICKNESS (in.)THICKNESS (mm)WEIGHT (oz/sq ft)WEIGHT (kg/m2)MAX. SIZE (in.)MAX. SIZE (mm)
Window glass SS 3/32 DS 1/8  2.4 3.2  19 26  5.8 7.8  40×50 60×80  1,020 x 1,270 1,520 x 2,030
Thick Sheet Glass     
3/164.84012.2120×843,050 x 2,130
7/325.64513.7120×843,050 x 2,130
1/46.35215.9120×843,050 x 2,130
3/89.57723.5160×844,060 x 2,130
7/1611.18626.260×841,520 x 2,130

How to calculate glass measurement

Step 1: Measure the glass

Find the edges of the glass frame.

Step 2: Measure the horizontal tight size

Leadbitter Glass recommends that you measure the dimension of the horizontal tight size. This is done by measuring the two outer edges on either side of the frame to get the required value.

Step 3: Measure the vertical tight size

Measure the vertical distance of the “tight size” from the top and bottom of the outer edges from left and right. Then record the dimension.

Step 4: Deduct ¼ inch from your results

Since the measurement was taken from the edges of the frame. It is pertinent that you deduct ¼ from the vertical dimension and also from the horizontal dimension. The result you get is the adjusted measurements. This adjustment is done so that the cut glass is smaller in size than the frame. But the adjusted measurement should only be a slight adjustment. It allows for the contraction and expansion of the glass to fit the frame.

What is the difference between measurement and calculations?

Measurement is the primary stage of getting requirements for a calculation. Whereas calculation is the second stage where the measured results are worked at to get a definite answer. 

According to Brainly, the actual figure of the given object is the measurement. On the other hand, a calculation is using the measured object and putting it into the formula to get the desired result.

How to calculate glass measurement: Tips 

  • To calculate the weight of glass per square foot, use the above formula strictly. However, if you are not able to get the certainty you expect, especially for your window, use the window glass size calculator.
  • According to Dan Vandervort’s, they recommend you take a scrap of the old glass to the store you will place your order. This is used by the manufacturers to determine the thickness of the glass to be replaced and the type of glass that will fit the old one.
  • You are also advised to desist from the assumption that the dimensions of the old glass are the same. It is a known fact that old frames are not always perfect.

Learn more: How to measure glass for aluminum window

Frequently Asked Question

How are measurements calculated?

Measurements are calculated by taking into account different mechanisms. The object of your measurement, the specific details of each dimension. The formula for the measurement is also taken into account. The result you want to arrive at is all that is taken into consideration when you calculate the measurement.

How do you estimate a measurement?

You can estimate a measurement by using a benchmark of the object that are similar. For estimating length, you can use centimeters, inches, yards, miles, and feet. While to determine a reasonable estimate of the mass of an object, you can use a similar object in kilogram, pounds, ounces, and kilogram.

How is the glass price calculated?

The price of glass is calculated by setting a markup for the glass per square inch or foot. Then you multiply it by the number or inch of glass you want to purchase to arrive at the price. In another instant, the thickness of the glass may also drive the cost of the glass. So, there is no single answer to what the price of glass is. Several factors will determine the glass price, then you multiply it by the amount you want to purchase.


How to calculate glass measurement is not all that complicated if you know the formula required to arrive at the square footage of the glass and the weight of the glass. This article has given the measurements and formulas you need to calculate glass measurements. Then a table the size of a glass sheet was highlighted with details in rows and columns.

Afterward, the difference between measurement and calculation is explained. Noting that measurement is the first stage, while calculation is the secondary stage. Thus, measurement is an integral part of the calculation.

Furthermore, useful tips that are necessary for calculating a glass measurement were enumerated. Best of luck in your glass replacement journey! Remember to always get expert opinions when you choose the type of glass you want to replace your old glass with. Because it will help you choose the best glass that will fit your budget.



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