Materials / Compare
Glass vs. Steel
Compare Glass vs. Steel strength, stiffness, weight and thermal properties.
| Try it on a partA sample part to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | not given (tensile used) | 385MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey), as reported by AISC |
| Ultimate tensile strength | 41MPasourcetypical mean surface tensile stress at fracture (MOR), 60 s load, weathered, 50% breakage probability | 505MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey) |
| Flexural strength | 41MPasourcemean MOR (same value as tensile) | not sourced |
| Elongation at break | not sourced | not sourced |
| Young's modulus (stiffness) | 72GPasourcetypical | 200GPasourcedesign value (AISC 360-16) |
| Density | 2,500kg/m³sourcetypical | 7,850kg/m³sourcenominal (constructional data) |
| Strength to weight | 16.4kN·m/kg | 49kN·m/kg2.99x higher |
| Stiffness to weight | 28.8MN·m/kg13% higher | 25.5MN·m/kg |
| Poisson's ratio | 0.22sourcetypical | 0.3sourcedesign value (AISC 360-16 Commentary) |
| Shear modulus | 29.5GPa | 76.9GPa2.61x stiffer in shear |
| Bulk modulus | 42.9GPa | 167GPa |
| Speed of sound | 5,367m/s | 5,048m/s |
| Thermal | ||
| Thermal conductivity | 0.937W/m·Ksourcetypical at 75 F | 48W/m·Ksourcenominal at 20 °C |
| Thermal expansion | 8.3µm/m·Ksourcetypical, 75-575 F | 12µm/m·Ksourcenominal (constructional data, no temperature range stated) |
| 100 mm part over a 50 °C swing | 41.5µm growth45% less | 60µm growth |
| Specific heat | 880J/kg·Ksourcetypical at 75 F | 460–480J/kg·Ksourcebase material: EN S275JR unalloyed structural steel (the EN counterpart of A36), typical, 50/100 °C |
| Heats up and cools (diffusivity) | 0.426mm²/s | 13mm²/s30.5x faster |
| Thermal shock resistance | 50.1W/m | 5,390W/m107x more resistant |
| Max service temperature | 511°Csourcestrain point (ASTM C336) - stress-relaxation onset, not a rated service limit | not sourced |
| Values for | Annealed soda-lime-silica float glass, Pilkington North America Technical Bulletin ATS-129 (04/2025) | Generic structural steel, cited as ASTM A992 (the current US structural grade): ASTM A992 W-shapes; Fy/Fu specified minimums from AISC publications (AISC 360-16 Commentary; Modern Steel Construction); elastic constants AISC 360; physical constants from the bauforumstahl structural-steel EPD, which names A992 among covered product standards. |
Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Questions
Is Glass stronger than Steel?
Steel is stronger: its yield strength is 385 MPa against tensile strength 41 MPa for Glass (9.39x).
Which is lighter, Glass or Steel?
Glass is lighter: 2,500 kg/m³ against 7,850 kg/m³ for Steel.
Which is stiffer, Glass or Steel?
Steel is stiffer: Young's modulus 200 GPa against 72 GPa for Glass, so the same part in Steel deflects less under the same load.
Which is lighter for the same job, Glass or Steel?
For the same stiffness or strength: Glass is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong panel or plate; Steel is lighter for a strong rod or tie, strong beam.
| Part that must be | Glass | Steel |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 13% heavier |
| Stiff beam (bending) | lighter | 1.88x heavier |
| Stiff panel or plate | lighter | 2.23x heavier |
| Strong rod or tie | 2.99x heavier | lighter |
| Strong beam | 42% heavier | lighter |
| Strong panel or plate | lighter | 2% heavier |
For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).
Which conducts heat better, Glass or Steel?
Steel conducts heat better: 48 W/m·K against 0.937 W/m·K for Glass.
Which expands less with temperature?
Glass expands less: 8.3 µm/m·K against 12 µm/m·K for Steel.