Aluminum Casting Weight Calculator
Quick Answer
For aluminum castings, weight ≈ part volume × alloy density. Common cast aluminum densities: A356 ≈ 2.68 g/cm³, A380/ADC12 ≈ 2.74 g/cm³, A413 ≈ 2.66 g/cm³. Multiply the net solid volume (cm³) by the alloy density to get net casting weight in grams; add gating, risers and machining stock for poured weight.
- Formula: weight (g) = volume (cm³) × alloy density (g/cm³)
- A356: 2.68 g/cm³ · A380/ADC12: 2.74 g/cm³ · A413: 2.66 g/cm³
- Net vs poured: add gating, risers and machining stock for the metal actually poured
- Cored cavities: subtract the void volume before multiplying by density
Estimate aluminum casting weight using real casting-alloy densities — A356, A380, ADC12, A413, 319, AlSi10Mg — not the generic 2.70 every other calculator assumes. The ~3% spread between the lightest (A413, 2.66) and heaviest (ADC12, 2.74) alloys changes part weight and cost. Includes CAD-volume input and poured weight.
How aluminum casting weight is calculated
Aluminum casting alloys span roughly 2.62–2.74 g/cm³. Die-cast parts (A380/ADC12) are slightly denser than sand/gravity-cast A356. Apply a ±2% guard band until first-article verification, as porosity lowers effective density.
Aluminum casting alloy density
| Alloy | Process | Density (g/cm³) |
|---|---|---|
| A356 / 356 | sand / gravity / investment | 2.68 |
| A380 | die casting | 2.73 |
| ADC12 | die casting | 2.74 |
| A413 | die casting | 2.66 |
| 319 | sand / permanent mould | 2.73 |
| AlSi10Mg | casting / additive | 2.68 |
A413/AlSi10Mg are the lightest common casting alloys; ADC12/A380/319 the heaviest. Use a custom density for alloys not listed.
Frequently Asked Questions
What is the density of aluminum casting alloys?
Common casting alloys range from about 2.66 g/cm³ (A413) to 2.74 (ADC12). A356 is 2.68, A380 is 2.73, 319 is 2.73, AlSi10Mg is 2.68. Pure aluminum is 2.70.
Why does A380 weigh more than A356?
A380 and ADC12 are die-casting alloys with more copper, zinc and iron, giving a higher density (~2.73–2.74) than the Al-Si-Mg alloy A356 (~2.68). For the same part geometry, A380 is about 2% heavier.
Does porosity change the cast weight?
Yes. Real castings contain some porosity, which lowers the effective density and the actual weight slightly below the calculated value. Allow a ±2% guard band and verify with a first-article weighing.
Which density should I use for die casting vs sand casting?
Use the alloy that matches your process: A380/ADC12/A413 for die casting, A356/319 for sand, gravity or investment casting. Pick the alloy in the dropdown and the correct density is applied automatically.
Can I calculate weight from a CAD model?
Yes — choose Custom Volume and enter the part volume from CAD in cm³ or in³. This is the most accurate method for real cast geometry.
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Related Resources
Aluminum Casting alloy grade chart — ASTM ↔ EN ↔ GB ↔ JIS
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 |
|---|---|---|---|---|
| A356 (T6) | 2.68 | 234 MPa min (T6) | JIS AC4C / EN AC-42000 AlSi7Mg / GB ZL101 | Structural, leak-tight, heat-treatable |
| A360 | 2.68 | 317 MPa | JIS ADC3 / EN AC-43400 AlSi10Mg / GB YL104 | Die cast, corrosion + strength |
| A380 | 2.74 | 324 MPa | JIS ADC10 / EN AC-46100 / GB YL113 | Most common die-casting alloy |
| A383 | 2.74 | 310 MPa | JIS ADC12 / EN AC-47100 | Thin-wall, intricate die castings |
| A413 | 2.66 | 290 MPa | JIS ADC1 / EN AC-44300 AlSi12 / GB YL102 | Pressure-tight, complex shapes |
| ADC12 | 2.7 | ≈ A383 (310 MPa) | JIS H5302 / EN AC-47100 | JIS-standard die casting (≈ A383) |
Frequently Asked Questions
How do you calculate the weight of a casting?
Casting weight = part volume × material density. Get the volume from your 3D/CAD model, select the alloy for its density (aluminum casting grades shown above), multiply to get grams, then divide by 1000 for kilograms. Add gating, risers and machining allowance for the as-cast weight.
Is A380 aluminum the same as ADC12?
Not exactly. A380 is closest to JIS ADC10, while A383 corresponds to JIS ADC12. A383/ADC12 has slightly higher silicon and lower copper than A380, giving better fluidity for thin walls. They are often substituted but differ in composition — confirm the spec for your application.
Why casting weight matters for aluminum parts
With aluminum castings, weight is rarely just a shipping number — it is the whole reason the part exists. Lightweighting is the core value proposition of cast aluminum: at roughly 2.70 g/cm³, aluminum is about one third the weight of iron or steel (around 7.1–7.85 g/cm³). Knowing the cast weight early lets you validate that switch from a ferrous part before you commit to tooling, and it is the single biggest lever on material cost, freight, and how the part behaves in the final assembly.
The math itself is simple and transparent: weight (kg) = part volume (cm³) × alloy density (g/cm³) ÷ 1000. The volume comes from your CAD model's mass-properties readout; the density comes from the alloy you choose. Among common cast aluminum alloys the density only shifts a little — LM6/AlSi12 at 2.65, A356 at 2.68, A380 at 2.71, ADC12/A383 at 2.74 — so swapping grades barely moves the scale. What the alloy choice really changes is cost, castability, and mechanical properties: gravity-cast A356 for leak-tight, heat-treatable structural parts versus high-volume die-cast ADC12 for thin, intricate housings. Use this calculator to lock in the weight target, then choose the alloy on properties and process — not on the small density difference. For background on the alloys and processes, see our aluminum casting overview.
Worked examples
A356 gravity-cast bracket (250 × 120 × 30 mm)
A solid rectangular bracket measuring 250 × 120 × 30 mm has a bounding volume of 250 × 120 × 30 = 900,000 mm³, which is 900 cm³ (divide by 1000). Casting it in A356 / AlSi7Mg at a density of 2.68 g/cm³:
900 cm³ × 2.68 g/cm³ ÷ 1000 = 2.41 kg
That 2.41 kg is the net part weight. The as-cast weight from the foundry will be higher once gating, risers, and machining stock are added — see the trust note below.
The same bracket in cast iron — the lightweighting case
To show why teams move to aluminum, take the identical 900 cm³ geometry and cast it in iron at 7.15 g/cm³ instead:
900 cm³ × 7.15 g/cm³ ÷ 1000 = 6.43 kg
Same shape, but the iron version weighs 6.43 kg versus 2.41 kg in A356 — a saving of about 4.0 kg, roughly 63% lighter. On a vehicle, robot arm, or anything that has to move or be carried, that mass reduction is exactly what justifies the cost of an aluminum casting and its tooling.
ADC12 die-cast housing with a cored cavity (subtract the void)
Real castings are rarely solid blocks. Take a die-cast housing with outer dimensions 180 × 100 × 60 mm and an internal cored cavity of 140 × 70 × 40 mm. Work out the net volume by subtracting the void:
Outer: 180 × 100 × 60 = 1080 cm³
Cavity: 140 × 70 × 40 = 392 cm³
Net volume: 1080 − 392 = 688 cm³
In ADC12 / A383 at 2.74 g/cm³:
688 cm³ × 2.74 g/cm³ ÷ 1000 = 1.89 kg
If you forgot the cored cavity and treated the part as solid (1080 cm³) you would get 2.96 kg — over 50% too heavy. Always use the true net volume from your CAD mass properties, which already accounts for cores, fillets, and draft.
Cast aluminum alloy density reference
Standard densities for the cast aluminum alloys you will most often weigh. Densities are stable enough to cite for estimating; the right grade is chosen on properties and casting process, not on these small differences.| Alloy / grade | Density (g/cm³) | Typical process & use |
|---|---|---|
| A356 / AlSi7Mg | 2.68 | Gravity die and sand casting; heat-treatable (T6), leak-tight structural parts, wheels and chassis brackets |
| A380 | 2.71 | High-pressure die casting; the most common general-purpose die alloy, good strength and castability |
| ADC12 / A383 | 2.74 | High-pressure die casting; excellent fluidity for thin walls and intricate housings (A383 is the ASTM near-equivalent of JIS ADC12) |
| LM6 / AlSi12 | 2.65 | Sand and gravity casting; near-eutectic, very fluid and pressure-tight, good for complex or marine parts |
| 6061 | 2.70 | Wrought alloy shown for comparison/machining reference; not a casting alloy but common in machined-from-billet and hybrid parts |
| Generic aluminum | ~2.70 | Use as a default when the exact cast alloy is not yet decided |
Densities are nominal room-temperature values for the alloy. Actual part density varies slightly with porosity, heat-treat temper, and exact chemistry within the spec. For comparison, gray/ductile iron sits near 7.1–7.3 g/cm³ and steel near 7.85 — about three times heavier than aluminum.
Who uses casting weight numbers
Estimating cast aluminum weight early matters across every industry where mass, cost, or assembly fit is on the line. In automotive and EV work, every kilogram removed from a bracket, housing, or battery component improves range and handling, so weight targets are set before the alloy is even chosen. Electronics and telecom teams weigh die-cast enclosures and heat-sink housings to balance thermal mass against shipping cost; lighting and consumer-product designers do the same for fixtures and bodies where feel and freight both count. Aerospace component engineers treat weight as a hard requirement, and pump and fluid-power makers use it to size castings against pressure-tight, leak-free targets. Across all of these, design engineers validate concepts, sourcing teams compare quotes on a per-kilogram basis, and product developers sanity-check whether a part can realistically hit its weight goal in aluminum.
How accurate is this estimate?
This calculator is deliberately transparent: it applies the universal formula weight = volume × density ÷ 1000 using published nominal densities for standard cast aluminum alloys. There is no hidden fudge factor — if you know your part's true volume, the net-part weight it returns is as accurate as that volume figure. It is, however, an indicative estimate, and the real as-cast and finished weight can differ for a few honest reasons:
- Gating, runners and risers add metal that is later cut off — the foundry's as-cast weight is higher than the net part weight.
- Machining allowance (extra stock on faces to be CNC-finished) raises the cast weight, then removes it in machining.
- Porosity and shrinkage mean actual density can sit slightly below the nominal value, especially in heavier sections.
- Alloy temper and exact chemistry within the specification shift density by a small amount.
- Cored cavities, draft and fillets change the true volume — always use CAD mass properties rather than a simple bounding box.
For a weight and price tied to your actual drawing and process, send us your part for a quote rather than relying on the estimate alone.
Glossary
- Die vs gravity vs sand casting
- Three ways to fill a mold with molten aluminum. Die casting forces metal into a steel mold under high pressure (fast, thin walls, high volume — e.g. ADC12/A380). Gravity (permanent-mold) casting pours into a reusable metal mold under gravity (denser, heat-treatable parts — e.g. A356). Sand casting pours into an expendable sand mold (low tooling cost, large or low-volume parts).
- Porosity
- Small voids or gas pockets trapped inside a casting. Porosity slightly lowers the part's effective density and can affect strength and pressure-tightness, which is why nominal density is a close estimate rather than an exact figure.
- Machining allowance
- Extra material left on surfaces that will be CNC-machined to final tolerance. It increases the as-cast weight, then is removed during finishing, so the cast weight is higher than the finished part weight.
- Alloy
- A metal blend; in cast aluminum the main additions are silicon (for fluidity), magnesium and copper (for strength). The alloy sets both the density used here and the casting process and mechanical properties — e.g. AlSi7Mg (A356) versus AlSi12 (LM6).
Why casting weight matters for aluminum parts
With aluminum castings, weight is rarely just a shipping number — it is the whole reason the part exists. Lightweighting is the core value proposition of cast aluminum: at roughly 2.70 g/cm³, aluminum is about one third the weight of iron or steel (around 7.1–7.85 g/cm³). Knowing the cast weight early lets you validate that switch from a ferrous part before you commit to tooling, and it is the single biggest lever on material cost, freight, and how the part behaves in the final assembly.
The math itself is simple and transparent: weight (kg) = part volume (cm³) × alloy density (g/cm³) ÷ 1000. The volume comes from your CAD model's mass-properties readout; the density comes from the alloy you choose. Among common cast aluminum alloys the density only shifts a little — LM6/AlSi12 at 2.65, A356 at 2.68, A380 at 2.71, ADC12/A383 at 2.74 — so swapping grades barely moves the scale. What the alloy choice really changes is cost, castability, and mechanical properties: gravity-cast A356 for leak-tight, heat-treatable structural parts versus high-volume die-cast ADC12 for thin, intricate housings. Use this calculator to lock in the weight target, then choose the alloy on properties and process — not on the small density difference. For background on the alloys and processes, see our aluminum casting overview.
Worked examples
A356 gravity-cast bracket (250 × 120 × 30 mm)
A solid rectangular bracket measuring 250 × 120 × 30 mm has a bounding volume of 250 × 120 × 30 = 900,000 mm³, which is 900 cm³ (divide by 1000). Casting it in A356 / AlSi7Mg at a density of 2.68 g/cm³:
900 cm³ × 2.68 g/cm³ ÷ 1000 = 2.41 kg
That 2.41 kg is the net part weight. The as-cast weight from the foundry will be higher once gating, risers, and machining stock are added — see the trust note below.
The same bracket in cast iron — the lightweighting case
To show why teams move to aluminum, take the identical 900 cm³ geometry and cast it in iron at 7.15 g/cm³ instead:
900 cm³ × 7.15 g/cm³ ÷ 1000 = 6.43 kg
Same shape, but the iron version weighs 6.43 kg versus 2.41 kg in A356 — a saving of about 4.0 kg, roughly 63% lighter. On a vehicle, robot arm, or anything that has to move or be carried, that mass reduction is exactly what justifies the cost of an aluminum casting and its tooling.
ADC12 die-cast housing with a cored cavity (subtract the void)
Real castings are rarely solid blocks. Take a die-cast housing with outer dimensions 180 × 100 × 60 mm and an internal cored cavity of 140 × 70 × 40 mm. Work out the net volume by subtracting the void:
Outer: 180 × 100 × 60 = 1080 cm³
Cavity: 140 × 70 × 40 = 392 cm³
Net volume: 1080 − 392 = 688 cm³
In ADC12 / A383 at 2.74 g/cm³:
688 cm³ × 2.74 g/cm³ ÷ 1000 = 1.89 kg
If you forgot the cored cavity and treated the part as solid (1080 cm³) you would get 2.96 kg — over 50% too heavy. Always use the true net volume from your CAD mass properties, which already accounts for cores, fillets, and draft.
Cast aluminum alloy density reference
Standard densities for the cast aluminum alloys you will most often weigh. Densities are stable enough to cite for estimating; the right grade is chosen on properties and casting process, not on these small differences.| Alloy / grade | Density (g/cm³) | Typical process & use |
|---|---|---|
| A356 / AlSi7Mg | 2.68 | Gravity die and sand casting; heat-treatable (T6), leak-tight structural parts, wheels and chassis brackets |
| A380 | 2.71 | High-pressure die casting; the most common general-purpose die alloy, good strength and castability |
| ADC12 / A383 | 2.74 | High-pressure die casting; excellent fluidity for thin walls and intricate housings (A383 is the ASTM near-equivalent of JIS ADC12) |
| LM6 / AlSi12 | 2.65 | Sand and gravity casting; near-eutectic, very fluid and pressure-tight, good for complex or marine parts |
| 6061 | 2.70 | Wrought alloy shown for comparison/machining reference; not a casting alloy but common in machined-from-billet and hybrid parts |
| Generic aluminum | ~2.70 | Use as a default when the exact cast alloy is not yet decided |
Densities are nominal room-temperature values for the alloy. Actual part density varies slightly with porosity, heat-treat temper, and exact chemistry within the spec. For comparison, gray/ductile iron sits near 7.1–7.3 g/cm³ and steel near 7.85 — about three times heavier than aluminum.
Who uses casting weight numbers
Estimating cast aluminum weight early matters across every industry where mass, cost, or assembly fit is on the line. In automotive and EV work, every kilogram removed from a bracket, housing, or battery component improves range and handling, so weight targets are set before the alloy is even chosen. Electronics and telecom teams weigh die-cast enclosures and heat-sink housings to balance thermal mass against shipping cost; lighting and consumer-product designers do the same for fixtures and bodies where feel and freight both count. Aerospace component engineers treat weight as a hard requirement, and pump and fluid-power makers use it to size castings against pressure-tight, leak-free targets. Across all of these, design engineers validate concepts, sourcing teams compare quotes on a per-kilogram basis, and product developers sanity-check whether a part can realistically hit its weight goal in aluminum.
How accurate is this estimate?
This calculator is deliberately transparent: it applies the universal formula weight = volume × density ÷ 1000 using published nominal densities for standard cast aluminum alloys. There is no hidden fudge factor — if you know your part's true volume, the net-part weight it returns is as accurate as that volume figure. It is, however, an indicative estimate, and the real as-cast and finished weight can differ for a few honest reasons:
- Gating, runners and risers add metal that is later cut off — the foundry's as-cast weight is higher than the net part weight.
- Machining allowance (extra stock on faces to be CNC-finished) raises the cast weight, then removes it in machining.
- Porosity and shrinkage mean actual density can sit slightly below the nominal value, especially in heavier sections.
- Alloy temper and exact chemistry within the specification shift density by a small amount.
- Cored cavities, draft and fillets change the true volume — always use CAD mass properties rather than a simple bounding box.
For a weight and price tied to your actual drawing and process, send us your part for a quote rather than relying on the estimate alone.
Glossary
- Die vs gravity vs sand casting
- Three ways to fill a mold with molten aluminum. Die casting forces metal into a steel mold under high pressure (fast, thin walls, high volume — e.g. ADC12/A380). Gravity (permanent-mold) casting pours into a reusable metal mold under gravity (denser, heat-treatable parts — e.g. A356). Sand casting pours into an expendable sand mold (low tooling cost, large or low-volume parts).
- Porosity
- Small voids or gas pockets trapped inside a casting. Porosity slightly lowers the part's effective density and can affect strength and pressure-tightness, which is why nominal density is a close estimate rather than an exact figure.
- Machining allowance
- Extra material left on surfaces that will be CNC-machined to final tolerance. It increases the as-cast weight, then is removed during finishing, so the cast weight is higher than the finished part weight.
- Alloy
- A metal blend; in cast aluminum the main additions are silicon (for fluidity), magnesium and copper (for strength). The alloy sets both the density used here and the casting process and mechanical properties — e.g. AlSi7Mg (A356) versus AlSi12 (LM6).