Gray Cast Iron Plate Weight
Mass per square metre for gray cast iron plate at 7,200 kg/m³ (ASTM A48 Class 30 / ISO 185). Plate is sold by area, so every figure here is per square metre rather than per metre of length.
At the reference dimensions (w = 1000 mm, t = 10 mm) this section has a cross-sectional area of 10,000.0 mm², giving 72.00 kg/m² (14.75 lb/ft²). Against carbon steel's 7,850 kg/m³ that is -8.3 % — the same section in steel would be 78.50 kg/m².
Plate — formula and derivation
Area of a plate
A = w · t
A = w × t. For plate the useful output is mass per unit area: m″ = t × ρ
Worked through with the default dimensions:
A = w × tA = 1000 × 10A = 10000.0 mm²Per square metre: 10 mm × 1 m² = 0.0100 m³/m²
- w
- Width
- t
- Thickness
Weight follows from the area with no further geometry: m = A × 10⁻⁶ × ρ, where A is in mm², ρ in kg/m³ and m in kg/m. At 7,200 kg/m³ that is 72.0000 kg/m for the reference size above.
Cast iron plate — size series
| Width | Cross-section | Mass / length | Mass / area |
|---|---|---|---|
| 0.5 mm | 500.00 mm² · 0.7750 in² | 3.600 kg/m · 2.419 lb/ft | 3.60 kg/m² · 0.74 lb/ft² |
| 0.8 mm | 800.00 mm² · 1.2400 in² | 5.760 kg/m · 3.871 lb/ft | 5.76 kg/m² · 1.18 lb/ft² |
| 1.0 mm | 1,000.00 mm² · 1.5500 in² | 7.200 kg/m · 4.838 lb/ft | 7.20 kg/m² · 1.47 lb/ft² |
| 1.2 mm | 1,200.00 mm² · 1.8600 in² | 8.640 kg/m · 5.806 lb/ft | 8.64 kg/m² · 1.77 lb/ft² |
| 1.5 mm | 1,500.00 mm² · 2.3250 in² | 10.800 kg/m · 7.257 lb/ft | 10.80 kg/m² · 2.21 lb/ft² |
| 2.0 mm | 2,000.00 mm² · 3.1000 in² | 14.400 kg/m · 9.676 lb/ft | 14.40 kg/m² · 2.95 lb/ft² |
| 3.0 mm | 3,000.00 mm² · 4.6500 in² | 21.600 kg/m · 14.515 lb/ft | 21.60 kg/m² · 4.42 lb/ft² |
| 4.0 mm | 4,000.00 mm² · 6.2000 in² | 28.800 kg/m · 19.353 lb/ft | 28.80 kg/m² · 5.90 lb/ft² |
| 5.0 mm | 5,000.00 mm² · 7.7500 in² | 36.000 kg/m · 24.191 lb/ft | 36.00 kg/m² · 7.37 lb/ft² |
| 6.0 mm | 6,000.00 mm² · 9.3000 in² | 43.200 kg/m · 29.029 lb/ft | 43.20 kg/m² · 8.85 lb/ft² |
| 8.0 mm | 8,000.00 mm² · 12.4000 in² | 57.600 kg/m · 38.705 lb/ft | 57.60 kg/m² · 11.80 lb/ft² |
| 10 mm | 10,000.00 mm² · 15.5000 in² | 72.000 kg/m · 48.382 lb/ft | 72.00 kg/m² · 14.75 lb/ft² |
| 12 mm | 12,000.00 mm² · 18.6000 in² | 86.400 kg/m · 58.058 lb/ft | 86.40 kg/m² · 17.70 lb/ft² |
| 16 mm | 16,000.00 mm² · 24.8000 in² | 115.200 kg/m · 77.411 lb/ft | 115.20 kg/m² · 23.59 lb/ft² |
| 20 mm | 20,000.00 mm² · 31.0001 in² | 144.000 kg/m · 96.764 lb/ft | 144.00 kg/m² · 29.49 lb/ft² |
| 25 mm | 25,000.00 mm² · 38.7501 in² | 180.000 kg/m · 120.954 lb/ft | 180.00 kg/m² · 36.87 lb/ft² |
| 30 mm | 30,000.00 mm² · 46.5001 in² | 216.000 kg/m · 145.145 lb/ft | 216.00 kg/m² · 44.24 lb/ft² |
| 40 mm | 40,000.00 mm² · 62.0001 in² | 288.000 kg/m · 193.527 lb/ft | 288.00 kg/m² · 58.99 lb/ft² |
| 50 mm | 50,000.00 mm² · 77.5002 in² | 360.000 kg/m · 241.909 lb/ft | 360.00 kg/m² · 73.73 lb/ft² |
| 60 mm | 60,000.00 mm² · 93.0002 in² | 432.000 kg/m · 290.291 lb/ft | 432.00 kg/m² · 88.48 lb/ft² |
Computed for Cast iron at 7200 kg/m³ (0.2601 lb/in³). ASTM A48 Class 30 / ISO 185.
Each row is one nominal size. The thickness column drives everything: mass per square metre is thickness × density, so it scales in a straight line.
Imperial sizes
Plate is also bought in inch sizes. The conversions below are exact (1 in = 25.4 mm by definition), so the metric equivalents are the true millimetre dimensions rather than a rounded nominal figure.
| Stock size | Metric equivalent mm | Cross-section | Mass per unit area |
|---|---|---|---|
| 3/16 in | 4.76 | 4,762.50 mm² · 7.3819 in² | 34.29 kg/m² · 7.02 lb/ft² |
| 1/4 in | 6.35 | 6,350.00 mm² · 9.8425 in² | 45.72 kg/m² · 9.36 lb/ft² |
| 5/16 in | 7.94 | 7,937.50 mm² · 12.3031 in² | 57.15 kg/m² · 11.71 lb/ft² |
| 3/8 in | 9.52 | 9,525.00 mm² · 14.7638 in² | 68.58 kg/m² · 14.05 lb/ft² |
| 1/2 in | 12.70 | 12,700.00 mm² · 19.6850 in² | 91.44 kg/m² · 18.73 lb/ft² |
| 5/8 in | 15.88 | 15,875.00 mm² · 24.6063 in² | 114.30 kg/m² · 23.41 lb/ft² |
| 3/4 in | 19.05 | 19,050.00 mm² · 29.5276 in² | 137.16 kg/m² · 28.09 lb/ft² |
| 1 in | 25.40 | 25,400.00 mm² · 39.3701 in² | 182.88 kg/m² · 37.46 lb/ft² |
| 1-1/4 in | 31.75 | 31,750.00 mm² · 49.2126 in² | 228.60 kg/m² · 46.82 lb/ft² |
| 1-1/2 in | 38.10 | 38,100.00 mm² · 59.0551 in² | 274.32 kg/m² · 56.19 lb/ft² |
| 2 in | 50.80 | 50,800.00 mm² · 78.7402 in² | 365.76 kg/m² · 74.91 lb/ft² |
Stock sizes in inches, converted exactly at 25.4 mm per inch. Material: Gray Cast Iron at 7200 kg/m³.
The same plate in every material
Geometry is fixed and only density changes, so this table is the whole material-selection question in one view. Gray Cast Iron is highlighted. The percentage column is against carbon steel, which is the figure most quotations are built on.
| Material | Density kg/m³ | lb/in³ | Mass / length kg/m | lb/ft | vs carbon steel |
|---|---|---|---|---|---|
| Carbon Steel | 7,850 | 0.2836 | 78.500 | 52.750 | +0.0 % |
| Stainless Steel 304 | 8,000 | 0.2890 | 80.000 | 53.758 | +1.9 % |
| Stainless Steel 316 | 8,000 | 0.2890 | 80.000 | 53.758 | +1.9 % |
| Stainless Steel 316L | 8,000 | 0.2890 | 80.000 | 53.758 | +1.9 % |
| Stainless Steel 430 | 7,700 | 0.2782 | 77.000 | 51.742 | -1.9 % |
| Aluminum 6061-T6 | 2,700 | 0.0975 | 27.000 | 18.143 | -65.6 % |
| Aluminum 5052-H32 | 2,680 | 0.0968 | 26.800 | 18.009 | -65.9 % |
| Aluminum 7075-T6 | 2,810 | 0.1015 | 28.100 | 18.882 | -64.2 % |
| Copper C11000 | 8,940 | 0.3230 | 89.400 | 60.074 | +13.9 % |
| Brass C36000 | 8,500 | 0.3071 | 85.000 | 57.117 | +8.3 % |
| Bronze C93200 | 8,800 | 0.3179 | 88.000 | 59.133 | +12.1 % |
| Titanium Grade 2 | 4,510 | 0.1629 | 45.100 | 30.306 | -42.5 % |
| Gray Cast Iron | 7,200 | 0.2601 | 72.000 | 48.382 | -8.3 % |
| Lead | 11,340 | 0.4097 | 113.400 | 76.201 | +44.5 % |
| Rigid PVC (Type I) | 1,400 | 0.0506 | 14.000 | 9.408 | -82.2 % |
| HDPE (PE 100) | 960 | 0.0347 | 9.600 | 6.451 | -87.8 % |
Same geometry throughout, so the only variable is density. Carbon steel is highlighted as the baseline.
A note on using this table for costing: mass is not price. Aluminium is roughly a third of steel's mass here, but per kilogram it costs several times more, so a straight swap rarely saves money — what it buys is reduced load on a structure or a vehicle.
About gray cast iron
The only common ferrous material lighter than steel, because the graphite flakes that give cast iron its damping and machinability also displace iron — 7,200 kg/m³ against steel’s 7,850, an 8.3 % saving. Those flakes are also why it fails in tension but excels in compression, and why engine blocks, machine bases and drainage products are cast iron. Normal spread is 7,150–7,350 kg/m³, so a large casting should always be weighed against the foundry’s own figure.
- Density
- 7,200 kg/m³ = 0.2601 lb/in³ · 0.9172× carbon steel · typical spread ±3 %
- Specification
- ASTM A48 Class 30 / ISO 185
- Equivalents
- EN GJL-250 · JIS FC250 · GB HT250
- Typical uses
- Machine tool bases · Engine blocks and manifolds · Drainage and soil pipe · Column and bracket castings
Density varies with graphite content and section thickness — thin sections cool faster and can differ from a heavy boss in the same casting.
About plate
Plate is the one product where the customer usually wants mass per unit area rather than per unit length, because plate is priced and handled by the square metre. Reducing thickness by a fraction of a millimetre has an outsized commercial effect: stepping a 6 mm floor plate down to 5 mm removes 16.7 % of the steel on a job that may be measured in thousands of square metres. That is also exactly why plate thickness tolerances are specified separately from the nominal value — a permitted negative tolerance on a nominally 6 mm plate is real money at scale.
Specified as thickness × width × length, plus the tolerance class and whether the pattern is plain, chequer or floor plate.
Download this data
Cast iron plate — CSV
Both buttons below read the tables rendered on this page, so the file matches what you are looking at. The full catalogue — all 16 materials across all 10 sections — is on the downloads page.
Fields are quoted per RFC 4180, with a UTF-8 byte-order mark so Excel reads the mm² and · characters correctly. Blank lines separate the weight matrix from the area matrix.
Frequently asked questions
How much does gray cast iron plate weigh?
At the reference thickness of 1000 mm, gray cast iron plate weighs 7,200.00 kg/m², which is 1,474.68 lb/ft². Weight per unit area is thickness multiplied by density, so it scales in a straight line: halve the thickness and you halve the weight.
How is the weight of plate calculated?
Weight is cross-sectional area × length × density. For this shape the area is A = w · t. At the reference dimensions that gives 10,000.0 mm², and multiplying by gray cast iron's density of 7,200 kg/m³ gives 72.000 kg/m. Nothing is looked up in a table — which is why a non-standard size is calculated just as accurately as a standard one.
Why does gray cast iron weigh more or less than steel?
It is lighter than carbon steel for the same section — about 8 % lighter at 7,200 kg/m³. Density is the only variable: the cross-sectional area depends purely on geometry, so a plate of the same dimensions has the same area in every material and the mass simply scales with density. In this case the ratio is 0.9172× carbon steel.
What is the cross-sectional area of a plate?
The area depends only on the dimensions, not on the material, so it is identical whichever material you select: at the reference dimensions it is 10,000.0 mm² (15.5000 in²). That is the number you would enter into a stress or deflection calculation, and it is why changing material on this page never changes the area column.
Does a cast iron plate weigh the same as a cast iron part of a different shape?
No, and the difference is larger than most people expect. At equal nominal size, a square bar is 27.3 % heavier than a round bar, and a hollow section is typically 60–80 % lighter than the solid bar it replaces. Weight follows area, and area changes faster than dimensions do — which is exactly why this needs calculating rather than estimating.
Other materials, same plate
The same geometry in every material, so the only variable is density.
- Carbon steel plate — 7850 kg/m³
- SS 304 plate — 8000 kg/m³
- SS 316 plate — 8000 kg/m³
- AL 6061 plate — 2700 kg/m³
- Copper plate — 8940 kg/m³
- Brass plate — 8500 kg/m³
- HDPE plate — 960 kg/m³
- PVC plate — 1400 kg/m³
Other Cast iron sections
The same density applied to every shape the site covers.
- Cast iron round bar — A = π/4 · d²
- Cast iron square bar — A = a²
- Cast iron hexagonal bar — A = (√3/2) · AF² ≈ 0.8660 · AF²
- Cast iron flat bar — A = w · t
- Cast iron round tube — A = π/4 · (D² − d²), d = D − 2t
- Cast iron square tube — A = a² − (a − 2t)²
Reference data and tools
- Metal weight overview — how the calculation works
- All 16 materials — densities and specifications
- All 10 sections — formulas and size series
- Density chart — lightest to heaviest
- Metal weight calculator — any size, any material
- All calculators — metal weight and pipe weight
- Download the data — CSV, generated from the same source
- Cross-reference tables — DN / NPS / material equivalents
- Methodology and sources — where every number comes from
Plate area from A = w · t. Mass computed as area × length × density at 7,200 kg/m³ (ASTM A48 Class 30 / ISO 185). No weight on this page is copied from a published table — which is why figures can differ in the last significant digit from a mill's chart calculated at a nominal density.
- Elementary plane geometry. The circle, polygon and hollow-section area formulas.
- ASTM material specifications for each grade named in the material entry (A36, A240/A276, B209/B211/B221, B152/B16/B505, B265/B348, A48, B29, D1784, D3350).
- BIPM / NIST definitional constants: international inch = 25.4 mm, foot = 0.3048 m, pound = 0.45359237 kg.
Dataset version 2026.09.1 · dimensions last verified against source 2026-09-21. Found an error? Report it — corrections are issued with a version bump.