Estimate the weight and cost of a gray iron and ductile iron part: pick the alloy grade (density is filled automatically), enter the part volume, and get the weight in kg and lb. Plus a full ASTM ↔ EN ↔ GB ↔ JIS grade cross-reference below.
Tip: get the exact volume from your 3D/CAD model (mass properties).
Estimate only (material + grade). Final cast weight includes gating/risers & machining stock — send your drawing for an exact quote.
Density and minimum properties per ASTM specification. Cross-standard equivalents are by composition/class for reference — confirm exact interchange for critical parts.
| Grade | Density (g/cm³) | Tensile (per ASTM) | Cross-standard equivalent | Typical use |
|---|---|---|---|---|
| Gray Iron — ASTM A48 Class 30 | 7.15 | 207 MPa (30 ksi) tensile | EN-GJL-200 / GB HT200 | General machinery, housings |
| Gray Iron — ASTM A48 Class 40 | 7.2 | 276 MPa (40 ksi) tensile | EN-GJL-250 / GB HT250 | Gears, machine bases, wear parts |
| Gray Iron — ASTM A48 Class 50 | 7.25 | 345 MPa (50 ksi) tensile | EN-GJL-350 / GB HT350 | High-strength gray iron |
| Ductile Iron — ASTM A536 60-40-18 | 7.1 | 414/276 MPa, 18% elong | EN-GJS-400-18 / GB QT400-18 | Pressure parts, high ductility |
| Ductile Iron — ASTM A536 65-45-12 | 7.1 | 448/310 MPa, 12% elong | EN-GJS-450-10 / GB QT450-10 | Valves & pump bodies (general) |
| Ductile Iron — ASTM A536 80-55-06 | 7.1 | 552/379 MPa, 6% elong | EN-GJS-550-5 / GB QT550-5 | Gears, crankshafts |
| Ductile Iron — ASTM A536 100-70-03 | 7.15 | 689/483 MPa, 3% elong | EN-GJS-700-2 / GB QT700-2 | Heavy-duty, wear-resistant |
Casting weight = part volume × material density. Get the volume from your 3D/CAD model, select the alloy for its density (cast iron grades shown above), multiply to get grams, then divide by 1000 for kilograms. Add gating, risers and machining allowance for the as-cast weight.
ASTM A536 65-45-12 is broadly equivalent to EN-GJS-450-10 and GB/T 1348 QT450-10 (ductile/nodular iron, ~450 MPa tensile, ~10% elongation). Composition and minimum properties are comparable; always confirm the exact controlling standard for critical parts.
For a sand-cast iron part, weight is one of the first numbers that drives the conversation. Foundries pour by the kilogram, so the as-cast weight feeds directly into material cost, melt scheduling, and the freight you will pay to ship finished castings. Getting a reliable weight estimate before tooling is cut lets you compare grades, sanity-check a supplier quote, and catch an over-engineered design while it is still cheap to change.
The arithmetic is the same for every ferrous alloy: weight (kg) = part volume (cm³) × density (g/cm³) ÷ 1000. What changes between iron grades is the density you plug in. Grey iron and ductile (nodular) iron sit remarkably close together — roughly 7.15 versus 7.10 g/cm³ — so for the same geometry the two weigh almost the same. That small density gap is easy to overlook, and on a single part it barely moves the number. The grades diverge dramatically on properties instead: ductile iron's spheroidal graphite gives it real ductility and impact strength, while grey iron's flake graphite makes it stiff, damping, and easy to machine but brittle. So weight alone never tells you which grade is right — it tells you the material mass you are buying once the grade is chosen.
Use this calculator to convert a CAD-model volume into a grade-specific weight, then treat the result as a baseline. The true poured weight is higher than the finished-part weight because of gating, risers, and machining stock — see the worked examples and notes below for how to account for that. For the property side of the grey-versus-ductile decision, see Gray Iron vs Ductile Iron.
A rectangular cover, 300 mm × 200 mm × 25 mm, in grey cast iron (ASTM A48 Class 30, density 7.15 g/cm³).
This is the solid-part weight. For the actual poured weight, add gating, risers, and any machining stock on faces you will finish.
Pour the identical 1,500 cm³ cover in ductile (nodular) iron (ASTM A536 65-45-12, density 7.10 g/cm³) instead.
The weight drops by only about 0.08 kg — under 1% — because the densities are so close. But the mechanical step is large: the ductile-iron cover gains roughly 12% elongation and far better impact resistance, where the grey-iron version is brittle and would crack rather than bend. The lesson: switching grades barely changes the weight, so never pick a grade to save mass — pick it for the properties the part needs.
A ductile-iron flanged housing made from a 250 × 250 × 20 mm plate with a cored through-bore of Ø60 mm running 80 mm long. The core removes iron, so subtract that volume.
Cores, drillings, and pockets all reduce the finished weight — model the true net volume (CAD mass properties handle this automatically) rather than the bounding box.
| Iron family | Density (g/cm³) | Typical property / use note |
|---|---|---|
| Grey cast iron (flake graphite) | 7.15 (7.0–7.3) | Excellent machinability, vibration damping and compressive strength; brittle in tension. Housings, machine bases, brake parts, manifolds. |
| Ductile / nodular iron (SG iron) | 7.10 | Spheroidal graphite gives high tensile strength plus real ductility and impact resistance. Pressure-bearing parts, pipe fittings, automotive components. |
| Malleable iron | 7.30 | Heat-treated white iron with tempered-carbon nodules; tough and good for thin sections and small fittings. Pipe fittings, brackets, agricultural hardware. |
| White / high-chrome iron | ~7.70 | Very hard, carbide-rich and highly wear-resistant but brittle and hard to machine. Grinding balls, pump liners, abrasion-resistant wear parts. |
| Austempered ductile iron (ADI) | ~7.10 | Ductile iron given an austempering heat treatment for a steel-like strength-to-weight ratio with good fatigue and wear performance. Gears, suspension and drivetrain parts. |
Densities are indicative reference values for weight estimating, not guaranteed specification limits. Actual density shifts with carbon equivalent, graphite morphology, alloying, and porosity. For exact mass on tight-tolerance parts, weigh a first-article casting.
Accurate weight estimates matter across every sector that buys iron castings, and to several roles within each. In automotive, design engineers trade grey iron's damping for ductile iron's strength on housings, brackets, and brake components. Agricultural and construction machinery rely on tough ductile and ADI parts for drivetrains, linkages, and ground-engaging hardware. Municipal and waterworks buyers specify ductile iron for manhole covers, gratings, and pipe fittings where impact resistance is non-negotiable. Pumps and valves use both grey and ductile bodies depending on pressure rating, while machine tool builders favour grey iron beds and columns for stiffness and vibration absorption. Counterweights are the opposite case — the part exists to add mass, so dense iron is the point. Buyers use these estimates to validate quotes, design engineers to compare grades and check shipping mass, and estimators to build material cost into a bid before tooling is committed.
This tool uses the transparent, industry-standard relationship weight = volume × density ÷ 1000, with density values drawn from the standard published ranges for each cast-iron family (grey iron ≈ 7.15, ductile iron ≈ 7.10, malleable ≈ 7.30, white/high-chrome ≈ 7.7, ADI ≈ 7.1 g/cm³). There is no hidden adjustment — the result is purely your entered volume multiplied by the selected grade's density. It is an indicative engineering estimate, not a guaranteed cast weight, and the real number can differ for several legitimate reasons:
For a binding weight on a tolerance-critical part, send your drawing for a quote and weigh a first-article casting rather than relying on a calculated value.
Only very slightly. Ductile iron's density (≈7.10 g/cm³) is marginally below grey iron's (≈7.15 g/cm³), so an identical part is under about 1% lighter in ductile iron. That difference is negligible in practice — the two grades are chosen for their mechanical properties, not to save weight.
It depends entirely on the geometry and process, so there is no single multiplier. The poured weight adds gating, risers and feed metal (later removed), and the as-cast part also carries machining stock on finished faces. For an exact figure, model the rigging and finished part separately or weigh a first-article casting.
Among common iron families, white and high-chrome irons are the densest at roughly 7.7 g/cm³, followed by malleable iron at about 7.30; grey and ductile iron sit near 7.10–7.15. Because the calculator multiplies your volume by the selected grade's density, switching to a denser iron raises the estimated weight proportionally for the same geometry.