Glass Thickness Converter
Convert glass thickness between millimeters, fractional inches, and calculate weight per square foot and square meter for common glass types.
Enter a glass thickness — see the conversion and weight per area.
6 mm (1/4") = 3.07 lb/sq ft — Tempered, shower doors
10 mm (3/8") = 5.12 lb/sq ft — Tabletops, railings
Understanding Glass Thickness Measurements
Glass thickness is specified in millimeters in most of the world but in fractional inches in the United States. Converting between these systems is essential when ordering glass, specifying glazing for construction projects, or comparing products from different manufacturers. Glass weight calculations are important for structural support design and shipping estimates.
Standard Glass Thicknesses:
Glass is manufactured in standard thicknesses. The nominal sizes do not always convert to exact fractions:
| Millimeters | Inches (exact) | Common Fraction | Common Name |
|---|---|---|---|
| 2 mm | 0.079" | 5/64" | Picture frame glass |
| 2.5 mm | 0.098" | 3/32" | Single-strength (SS) |
| 3 mm | 0.118" | 1/8" | Double-strength (DS) |
| 4 mm | 0.157" | 5/32" | Standard window glass |
| 5 mm | 0.197" | 3/16" | Shelving, heavier windows |
| 6 mm | 0.236" | 1/4" | Standard tempered, shower doors |
| 8 mm | 0.315" | 5/16" | Heavy glazing, tabletops |
| 10 mm | 0.394" | 3/8" | Tabletops, balustrades |
| 12 mm | 0.472" | 1/2" | Heavy commercial, structural |
| 15 mm | 0.591" | 19/32" | Structural glazing |
| 19 mm | 0.748" | 3/4" | Heavy structural, aquariums |
| 22 mm | 0.866" | 7/8" | Special applications |
| 25 mm | 0.984" | 1" | Heavy-duty commercial |
Weight Calculation Formulas:
Standard float glass has a density of approximately 2,500 kg/m³ (156 lb/ft³):
Weight per sq ft (lb) = thickness (inches) × 13.0
Weight per sq m (kg) = thickness (mm) × 2.5
Or more precisely:
Weight (kg/m²) = thickness (mm) × 2.5
Weight (lb/ft²) = thickness (mm) × 0.512
Glass Weight Reference:
| Thickness | Weight per sq ft (lb) | Weight per sq m (kg) |
|---|---|---|
| 2 mm | 1.02 lb | 5.0 kg |
| 3 mm | 1.54 lb | 7.5 kg |
| 4 mm | 2.05 lb | 10.0 kg |
| 5 mm | 2.56 lb | 12.5 kg |
| 6 mm | 3.07 lb | 15.0 kg |
| 8 mm | 4.10 lb | 20.0 kg |
| 10 mm | 5.12 lb | 25.0 kg |
| 12 mm | 6.15 lb | 30.0 kg |
| 19 mm | 9.73 lb | 47.5 kg |
Practical Examples:
- A standard residential window uses 3 mm (1/8 inch) double-strength glass, weighing about 1.54 lb per square foot (7.5 kg per square meter).
- A frameless shower door typically uses 3/8 inch (10 mm) tempered glass, weighing 5.12 lb/sq ft. A standard 30"×72" shower panel weighs about 76 pounds (34.5 kg).
- A 4 ft × 8 ft glass tabletop in 1/2 inch (12 mm) glass weighs approximately 197 lb (89 kg).
- Laminated glass (two layers bonded with PVB interlayer) weighs approximately double the single-layer weight for the same total thickness.
Tips:
- Tempered glass is the same thickness as regular glass but is 4-5 times stronger. The thickness does not change during the tempering process.
- Insulated glass units (IGUs or double-pane windows) use two panes separated by an air or gas gap. A typical IGU might be 3mm + 12mm gap + 3mm = 18mm total thickness.
- For safety glazing in doors and low windows, most building codes require tempered or laminated glass of at least 6 mm (1/4 inch).
- When shipping glass panels, account for packing materials adding 20-30% to the glass weight alone.