Steel Density Table — Weight per Unit Volume Reference
Steel density is a fundamental property used in dead load calculations, weight estimates, and material takeoffs. Structural carbon steel has a density of 490 lb/ft^3 (7,850 kg/m^3). This page provides density values for structural materials commonly encountered alongside steel in building design.
Structural steel density
| Property | Imperial | Metric |
|---|---|---|
| Density | 490 lb/ft^3 | 7,850 kg/m^3 |
| Unit weight | 490 pcf | 76.97 kN/m^3 |
| Density (alternative) | 0.2836 lb/in^3 | 7.85 g/cm^3 |
This value applies to all common structural carbon steels: ASTM A36, A572, A992, A500, A53, A913, and their international equivalents (AS/NZS 3678/3679, EN 10025 S235/S275/S355). Alloy composition variations have negligible effect on density -- all structural steels are within 0.5% of 490 pcf.
Density of related structural materials
| Material | lb/ft^3 | kg/m^3 | kN/m^3 | Notes |
|---|---|---|---|---|
| Carbon steel (structural) | 490 | 7,850 | 76.97 | A36, A992, A572, etc. |
| Stainless steel (304) | 500 | 8,000 | 78.5 | Higher due to chromium/nickel |
| Stainless steel (316) | 500 | 8,000 | 78.5 | Similar to 304 |
| Cast iron | 450 | 7,200 | 70.6 | Historical structures |
| Wrought iron | 480 | 7,700 | 75.5 | Historical structures |
| Aluminum (6061-T6) | 169 | 2,710 | 26.6 | ~1/3 of steel |
| Normal-weight concrete | 150 | 2,400 | 23.5 | With reinforcement |
| Lightweight concrete | 110 | 1,760 | 17.3 | Expanded shale/clay aggregate |
| Reinforced concrete | 150 | 2,400 | 23.5 | ASCE 7 default |
| Wood (Douglas Fir) | 34 | 545 | 5.3 | Air-dry, ~12% MC |
| Wood (Southern Pine) | 37 | 593 | 5.8 | Air-dry, ~12% MC |
| Masonry (solid brick) | 120 | 1,920 | 18.8 | Varies with mortar |
| Masonry (CMU, grouted) | 135 | 2,160 | 21.2 | Fully grouted |
| Glass | 160 | 2,560 | 25.1 | Plate glass |
| Water | 62.4 | 1,000 | 9.81 | For ponding and tank loads |
| Soil (average) | 110 | 1,760 | 17.3 | Varies widely |
Weight calculations for steel members
The weight per linear foot of a steel member is given by the W-shape designation. For example, W16x40 weighs 40 lb/ft. For plates and other non-standard shapes:
Weight (lb/ft) = cross-sectional area (in^2) * 3.4
This uses: 490 lb/ft^3 / 144 in^2/ft^2 = 3.4 lb/(ft*in^2).
Plate weight formula
Weight (lb) = L * W * t * 490 / 1728
Where L = length (in), W = width (in), t = thickness (in). Or in simpler form:
Weight (lb/ft^2) = t (in) * 40.8
| Plate Thickness | Weight (lb/ft^2) | Weight (kg/m^2) |
|---|---|---|
| 1/4" | 10.2 | 49.8 |
| 3/8" | 15.3 | 74.7 |
| 1/2" | 20.4 | 99.6 |
| 5/8" | 25.5 | 124.5 |
| 3/4" | 30.6 | 149.4 |
| 1" | 40.8 | 199.2 |
| 1-1/2" | 61.2 | 298.8 |
| 2" | 81.6 | 398.4 |
Steel weight for dead load calculations
In dead load calculations, the self-weight of steel framing is typically estimated as:
| Framing Type | Estimated Weight |
|---|---|
| Light steel framing (residential) | 5-8 psf |
| Steel floor framing (office) | 8-12 psf |
| Heavy steel framing (industrial) | 12-20 psf |
| Steel roof framing (simple) | 3-6 psf |
| Steel roof framing (long span) | 6-12 psf |
| Metal deck (1.5" composite) | 2-3 psf (deck only) |
| Metal deck + concrete (3.25" LW) | 40-45 psf |
These are preliminary estimates for initial sizing. Final dead loads must be calculated from the actual member sizes selected.
Unit conversions
| From | To | Multiply by |
|---|---|---|
| lb/ft^3 | kg/m^3 | 16.018 |
| kg/m^3 | lb/ft^3 | 0.06243 |
| kN/m^3 | lb/ft^3 | 6.366 |
| lb/ft^3 | kN/m^3 | 0.1571 |
| lb/ft | kg/m | 1.488 |
| kg/m | lb/ft | 0.6720 |
Common mistakes
Using 480 lb/ft^3 for steel. Some older references use 480 pcf. The AISC-accepted value is 490 pcf (7,850 kg/m^3).
Confusing density with unit weight. Density is mass per volume (kg/m^3). Unit weight is force per volume (kN/m^3 or pcf). In US practice, "density" in pcf is actually unit weight (since 1 lb-mass weighs 1 lb-force at standard gravity).
Not including connection weight. Connections typically add 5-15% to the steel member weight. For material takeoffs, a connection allowance of 10% is common.
Using normal-weight concrete density for lightweight concrete. Lightweight concrete is 110 pcf vs. 150 pcf for normal-weight. Using the wrong value significantly affects dead load calculations.
Forgetting fireproofing weight. Spray-applied fireproofing adds 1-3 psf depending on the required thickness and rating.
Frequently asked questions
What is the density of structural steel? 490 lb/ft^3 (7,850 kg/m^3). This applies to all common structural carbon steels (A36, A992, A572, etc.) and varies by less than 0.5% across grades.
How do I calculate the weight of a steel plate? Weight (lb) = length (in) _ width (in) _ thickness (in) _ 490 / 1728. Or use the quick formula: weight per square foot = thickness (in) _ 40.8 lb/ft^2.
What is the difference between density and unit weight? Density is mass per unit volume (kg/m^3). Unit weight (or specific weight) is weight per unit volume (kN/m^3 or pcf). In US customary units, the numerical values are the same because 1 lbm = 1 lbf at standard gravity.
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Related references
Disclaimer
This page is for educational and reference use only. It does not constitute professional engineering advice. All design values must be verified against the applicable standard and project specification. The site operator disclaims liability for any loss arising from the use of this information.