Glass Weight Calculator
Estimate what a piece of glass weighs before you lift, ship, or mount it. Enter width and height in inches, pick a thickness from 3/32 to 3/4 inch, set the pane count, and get weight in pounds and kilograms plus lb per square foot.
Example: with Width (inches) 36 · Height (inches) 24 · Thickness 1/4 in (6 mm) — shelves, insulated units · Number of panes 1 → Glass weight: 19.5 lb.
- In kilograms8.85 kg
- Weight per square foot3.25 lb/sq ft at this thickness
Computed by the calculator below using its default values. Change any input to see your own numbers.
Soda-lime glass has a density of 2.5 g/cm³ — about 1.63 lb per square foot for every 1/8 inch of thickness.
Glass weight is pure geometry times density
Standard soda-lime glass — windows, shelves, tabletops, shower doors — has a density of about 2.5 g/cm³, or 0.0903 lb per cubic inch. Weight is simply width × height × thickness × density. The trade shortcut that falls out of this: every 1/8 inch of thickness weighs about 1.63 lb per square foot. A 36 × 24 inch shelf in 1/4-inch glass is 6 square feet at 3.25 lb/sq ft, so about 19.5 lb.
Tempering does not change the weight: tempered and annealed glass are the same material, just heat-treated differently. Low-iron ('starphire') glass is also effectively the same density.
Multi-pane and laminated units
A double-pane insulated window unit weighs its two panes plus a negligible spacer and seal, so set the pane count to 2 (or 3 for triple glazing). Laminated glass — two layers bonded over a plastic interlayer, as in car windshields and some shower panels — weighs about the same as the two glass layers alone; the interlayer is thin and lighter than glass. Mirror weighs the same as glass of its thickness plus a trivial backing coat. When mounting, always size French cleats, standoffs, or shelf brackets to total glass weight with margin.
How it’s calculated
Weight = width × height × thickness × 0.0903 lb/in³ × panes, dimensions in inches. The 0.0903 lb/in³ figure is soda-lime glass at 2.5 g/cm³ (about 156 lb/cu ft). Per-square-foot figure = thickness × 0.0903 × 144. Kilograms = lb × 0.45359237.
Densities are for common soda-lime float glass — borosilicate runs about 10% lighter and lead crystal 20%+ heavier, and nominal thickness can differ slightly from actual.
Glass weight per square foot
| Thickness | Weight |
|---|---|
| 1/8 in (3 mm) | 1.63 lb/sq ft |
| 3/16 in (5 mm) | 2.44 lb/sq ft |
| 1/4 in (6 mm) | 3.25 lb/sq ft |
| 3/8 in (10 mm) | 4.88 lb/sq ft |
| 1/2 in (12 mm) | 6.50 lb/sq ft |
Computed at 2.5 g/cm³ (0.0903 lb/in³); annealed and tempered glass weigh the same.
Common mistakes
- Reading a metric thickness as inches: 6 mm glass is about 1/4 inch, not 0.6 inch.
- Counting an insulated window unit as one pane when it contains two or three.
- Sizing wall anchors to the glass alone and forgetting frame, hardware, and dynamic load when a door swings.
- Assuming tempered glass is lighter — heat treatment changes strength, not density.
Frequently asked questions
What is the glass weight formula?
Weight (lb) = width(in) × height(in) × thickness(in) × 0.0903. The 0.0903 lb/in³ constant is standard glass density of 2.5 g/cm³. Multiply by pane count for insulated units.
How much does 1/4-inch glass weigh per square foot?
About 3.25 lb per square foot. The rule of thumb is 1.63 lb/sq ft per 1/8 inch of thickness, so 3/8-inch glass runs 4.88 and 1/2-inch runs 6.5 lb/sq ft.
Does tempered glass weigh more than regular glass?
No — tempering is a heat treatment that adds surface compression, not mass. Equal sizes of annealed and tempered glass weigh the same; the strength difference comes from internal stress, not density.
How heavy is a typical glass tabletop?
A 48-inch round in 1/2-inch glass is about 12.6 sq ft × 6.5 lb = 82 lb — a two-person lift. Always confirm the base is rated for the top, and use suction cups to carry large panes safely.