Glass Weight Calculator
Use this glass weight calculator to get pane weight from area and thickness: a 20 sq ft pane at 1/4 inch weighs about 65.02 lb, or 3.25 psf.
Glass weight calculator formula
A glass weight calculator multiplies the volume of the pane by the density of the glass. The formula is weight in pounds = area in square feet × 144 × thickness in inches × 0.0903.
The 144 turns square feet into square inches. The 0.0903 is the weight of one cubic inch of soda-lime glass in pounds. Enter the area and the thickness and you get the total weight and the weight per square foot (psf).
A shortcut worth remembering: glass weighs about 13 lb per square foot for every inch of thickness. A 1/4 inch pane is a quarter of that, so roughly 3.25 psf.
Worked examples
Example 1 is a fixed window, 20 sq ft at 1/4 inch.
- 20 × 144 = 2,880 square inches
- 2,880 × 0.25 = 720 cubic inches
- 720 × 0.0903 = 65.02 lb
- 65.02 ÷ 20 = 3.25 psf
Example 2 is a glass tabletop, 12 sq ft at 1/2 inch.
- 12 × 144 = 1,728 square inches
- 1,728 × 0.5 = 864 cubic inches
- 864 × 0.0903 = 78.02 lb
- 78.02 ÷ 12 = 6.50 psf
A 4 ft × 3 ft top at half an inch weighs about the same as one 80 lb bag of concrete mix. It is not a one-handed lift, and the table base has to carry it on top of whatever sits on the glass.
Weight per square foot by thickness
Inch thickness figures are the nominal values most glass is sold in.
| Thickness | Weight per sq ft | 20 sq ft pane |
|---|---|---|
| 1/8 in | 1.63 psf | 32.5 lb |
| 3/16 in | 2.44 psf | 48.8 lb |
| 1/4 in | 3.25 psf | 65.0 lb |
| 3/8 in | 4.88 psf | 97.6 lb |
| 1/2 in | 6.50 psf | 130.0 lb |
| 3/4 in | 9.75 psf | 195.0 lb |
Insulated glass units for windows are two panes with an air gap. The gap weighs almost nothing, so add the two glass thicknesses together. A typical unit with two 1/8 inch panes weighs about 3.25 psf, the same as one 1/4 inch pane.
How to measure the pane
- Measure the visible glass and add the part that sits inside the frame or channel. The pane the glazier orders is bigger than the view through it.
- Multiply height by width in feet. A pane 48 in × 30 in is 4 ft × 2.5 ft, or 10 sq ft.
- Read the thickness off the edge, or from the stamp in the corner of tempered glass. Use calipers if you can, because 1/4 inch and 5/16 inch look alike.
- For a laminated pane, measure the total thickness and subtract the interlayer if you want to be careful. The interlayer is thin, so the error is small.
- For several panes, find the weight of one and multiply. Do not add the areas first unless the panes are the same thickness.
What the number is used for
The weight tells you what the frame, the hinge, the post or the base has to hold. It also tells you how many people you need on moving day.
Sliding doors and large windows are the usual concern. A 6 ft × 8 ft patio door panel is 48 sq ft. At 3/8 inch that is about 234 lb, before the frame. Rollers and tracks are rated for a stated panel weight, so compare the two figures before you buy.
Glass railings and overhead glass are different. They are safety-critical, and the thickness, the type of glass and the way it is fixed come from the system’s engineering and from your local building code. Use this calculator to estimate handling and dead load, and leave the design to the railing manufacturer and a licensed professional.
For floors, roofs and walls that carry glass, add the figure to your other dead loads with the dead load calculator.
Common mistakes
- Using the nominal size of the window instead of the glass size. The glass is smaller than the rough opening.
- Entering thickness in millimeters. 6 mm is about 0.236 in. Convert first with the mm to inches calculator.
- Forgetting the second pane in an insulated unit or the second ply in laminated glass.
- Ignoring the frame. A vinyl or aluminum frame adds weight, and a wood frame adds more.
- Treating the result as the support requirement. Point loads, wind and impact are separate questions.
Related calculators
If you are pricing replacements, the double pane window cost calculator estimates installed cost. The steel weight calculator uses the same area-times-thickness method for plate and flat bar.
Frequently asked questions
What glass density does this calculator use?
It uses 0.0903 lb per cubic inch, which is the usual figure for soda-lime glass, the type in most windows, railings and tabletops. That works out to about 13 lb per square foot for every inch of thickness. Specialty glasses can differ a little, so confirm with the manufacturer if the load is critical.
Does tempered or laminated glass weigh differently than regular glass?
Tempered glass weighs the same as annealed glass of the same size and thickness, because heat treating does not change the density. Laminated glass is two or more plies plus a plastic interlayer, so its weight is close to the total glass thickness. Add the plies together and enter that figure.
Why does thickness matter so much to total weight?
Weight follows the volume of glass, and thickness is the only dimension that changes for a given pane size. Going from 1/4 inch to 3/8 inch adds half again as much weight. On a 30 sq ft pane that is about 146 lb instead of 97 lb.
How much heavier is a 1/2-inch pane than a 1/4-inch pane of the same size?
Exactly twice as heavy. A 20 sq ft pane is 65.02 lb at 1/4 inch and 130.03 lb at 1/2 inch. The weight per square foot goes from 3.25 to 6.50. Plan for two people and suction cups on anything over about 100 lb.
Estimates only. Verify quantities with your supplier before purchasing.