FRP / fibreglass weight & density
Pultruded FRP (fibreglass / GRP) has a density of about 1900 kg/m³ for standard E-glass/polyester — roughly a quarter of steel and 30% lighter than aluminium. The chart lists common pultruded sections by weight per metre and per foot; weigh any FRP profile from its geometry in the tool below.
| Size | Shape | Area · mm² | Weight · kg/m | Weight · lb/ft |
|---|---|---|---|---|
| I 120×60×6 | I-Beam | 1,368 | 2.599 | 1.747 |
| I 200×100×10 | I-Beam | 3,800 | 7.220 | 4.852 |
| CH 100×50×5 | Channel | 950 | 1.805 | 1.213 |
| L 50×50×6 | Angle | 564 | 1.072 | 0.720 |
| L 100×100×10 | Angle | 1,900 | 3.610 | 2.426 |
| SHS 50×50×5 | Square Hollow | 900 | 1.710 | 1.149 |
| CHS ⌀50×5 | Round Tube | 707 | 1.343 | 0.902 |
| ⌀25 rod | Round Rod | 491 | 0.933 | 0.627 |
| 50×6 flat | Flat Bar | 300 | 0.570 | 0.383 |
Computed from the exact section area × 1,900 kg/m³ (Pultruded FRP (E-glass / polyester)). Fillets excluded (<2%). Verify against certified data before release.
DXF (LWPOLYLINE/CIRCLE) · CSV/XLSX with X,Y columns (blank row = new loop). DWG → export as DXF first.
EL 23,000 MPa · Pultruded FRP (E-glass / polyester)
| Area | A | 5472 | mm² |
| Mass / metre | m | 10.397(6.986 lb/ft) | kg/m |
| 2nd moment | Ix | 4.754e+7 | mm⁴ |
| 2nd moment | Iy | 3.487e+6 | mm⁴ |
| Section mod. | Sx | 396173 | mm³ |
| Section mod. | Sy | 58118 | mm³ |
| Gyration | rx | 93.21 | mm |
| Gyration | ry | 25.24 | mm |
| Torsion | J | 262656 | mm⁴ |
| Published catalogue weight: 8.40 kg/m · computed Δ 24% | |||
Derived exactly from the section polygon (Green’s theorem). Fillets excluded (<2% effect). Verify against certified data before release.
The density of FRP / fibreglass
Standard pultruded FRP is about 1.9 g/cm³ (1900 kg/m³) for E-glass in a polyester or vinylester matrix — the exact figure depends on glass content, which is typically 50–70% by weight. High-fibre unidirectional rods run a little denser (≈2.0). That is around a quarter of steel's weight and about 70% of aluminium's, which is the whole point of FRP in corrosive and access-limited work.
Why FRP catalogue weights can differ from geometry
Published pultrusion weight tables sometimes assume a nominal density slightly different from pure geometry, and profiles carry a surface veil and resin-rich corners. Dimviz shows the computed engineering weight (area × density) next to the catalogue figure where known, so you can see and explain the small delta rather than being surprised by it.
Light enough to change the install
A pultruded FRP I-beam at a quarter of steel's weight can often be carried and installed by hand where a steel equivalent needs lifting gear. Combined with corrosion immunity and electrical insulation, the low density is why FRP wins in water treatment, chemical plant and rail trackside. Compare the same section in FRP, aluminium and steel in the tool.
FAQ
What is the density of FRP / fibreglass?+
About 1900 kg/m³ (1.9 g/cm³) for standard pultruded E-glass/polyester — roughly a quarter of steel and 30% lighter than aluminium. It varies with glass content.
How much lighter is FRP than steel?+
For the same section, FRP (≈1900 kg/m³) is about 24% of the weight of steel (7850 kg/m³) — roughly four times lighter.
How do I calculate FRP profile weight?+
Weight per metre = cross-sectional area (m²) × 1900. Dimviz integrates the exact area of the pultruded section and multiplies by density, and shows the catalogue weight alongside where known.