Density of Aluminum: The Complete Reference Guide

Every week, someone on our team fields a version of the same question: “What density should I use for this aluminum part?” Sometimes it’s a purchasing coordinator building a freight estimate. Sometimes it’s a design engineer cross-checking a weight budget. Sometimes it’s a customer who found three different numbers online and isn’t sure which one is correct.

I’ve been laser-cutting and processing aluminum since 2007. The density question sounds simple, but it hides genuine complexity — the right answer depends on the alloy, the unit system, and what you’re actually trying to calculate. Get it wrong, and you end up with a freight quote built on phantom weight, or a structural calculation that’s 4% off because you used the wrong alloy’s value.

This guide settles the number, explains why it is what it is, and tells you exactly when each value applies.

The Density of Aluminum You Need Right Now

Pure aluminum has a density of 2,700 kg/m³ (2.70 g/cm³ or 0.0975 lb/in³) at room temperature. That’s the value standardized by the Aluminum Association and the number you’ll find in the ASM Handbook, Volume 1.

Here it is across all common engineering unit systems:

Use 2,700 kg/m³ whenever you need a general-purpose value and don’t know the exact alloy. For specific grades — especially the copper-rich 2xxx series or the zinc-rich 7xxx series — use the alloy-specific density from the table in the next section. The variation across commercial alloys runs from roughly 2,640 to 2,810 kg/m³. I’ll explain exactly what drives that range.

For data source, please refer to the Metal Density Chart.

The Weight Formula You Can Use Today

For a quick weight estimate of any aluminum part:

Weight (kg) = Length (m) × Width (m) × Thickness (m) × 2,700

For imperial units:

Weight (lb) = Length (in) × Width (in) × Thickness (in) × 0.0975

Worked example — a 6061-T6 sheet blank, 1,000 mm × 500 mm × 3 mm:

Weight = 1.0 × 0.5 × 0.003 × 2,700 = 4.05 kg / 8.9 lb

That formula runs constantly in our quoting system. It’s also the starting point for every shipping manifest, pallet weight, and lifting fixture specification we produce.

Why the Density of Aluminum Is So Low — The Physics

This is what most articles skip, and it’s the part that actually gives you confidence in the number.

Aluminum’s FCC crystal structure sets the baseline

At room temperature, aluminum atoms pack into a face-centred cubic (FCC) crystal lattice. Understanding this structure lets you derive the density from first principles rather than just accepting a tabulated value.

An FCC unit cell contains exactly 4 atoms. The lattice parameter for aluminum is 4.046 Å (4.046 × 10⁻¹⁰ m). Running through the calculation:

• Unit cell volume = (4.046 × 10⁻¹⁰)³ = 6.629 × 10⁻²⁹ m³
• Mass per unit cell = 4 atoms × (26.982 g/mol) ÷ (6.022 × 10²³ atoms/mol) = 1.792 × 10⁻²² g
• Calculated density = (1.792 × 10⁻²⁵ kg) ÷ (6.629 × 10⁻²⁹ m³) = 2,703 kg/m³

The tiny gap between this calculated value and the measured 2,699–2,700 kg/m³ comes from lattice vacancies in real material. The point is: the density of aluminum is not an arbitrary measurement — it follows directly from atomic mass (26.98 — low among structural metals) and crystal packing. Iron’s atomic mass is 55.85, which is one of the main reasons iron is 2.9× denser than aluminum.

Aluminum vs. common structural metals

You’ll often hear that “aluminum is 1/3 the weight of steel.” That’s essentially correct for equal volumes — 2,700 ÷ 7,850 = 34.4%. But weight per volume is only half the story. I’ll address the full structural comparison later.

Density of Aluminum by Alloy Series — The Complete Reference Table

The density of aluminum alloys ranges from approximately 2,640 to 2,810 kg/m³. That 170 kg/m³ spread comes entirely from the alloying elements added to the aluminum base. Understanding which elements push density up and which push it down eliminates the confusion around why different sources quote different numbers.

Why alloying elements change aluminum density

Each element added to aluminum brings its own density, which displaces a proportional volume of the aluminum matrix. Here’s the effect of each major alloying element:

No other article targeting this keyword maps this element-by-element explanation. It’s the framework that makes every density value in the table below predictable, not arbitrary.

Full density reference table by alloy series

Source: Aluminum Association, Aluminum Standards and Data; ASM Handbook, Vol. 1.

Key practical takeaways from this table:

The most commonly laser-cut grades — 6061 and 6063 — sit at essentially pure aluminum density: 2,700 kg/m³. The 2,700 value is correct for 95% of sheet metal and precision fabrication work. You only need to reach for a different number if you’re working with 7075 (2,810 kg/m³) or 2024 (2,780 kg/m³), where the difference starts to matter in weight budgets.

Temper does not change aluminum density — ever

This is a question I get regularly, and the answer is unambiguous.

The same alloy in different tempers — O (annealed), T4, T6, H32 — always has identical density. The Aluminum Association confirms this across all published data. Here’s the proof for 6061:

Temper changes the microstructure — the distribution of precipitates, the dislocation density. It does not change the mass per unit volume. Yield strength nearly quintuples from O to T6. The weight formula uses the same density regardless.

I know this sounds obvious, but I’ve seen engineers hesitate to use the standard 2,700 value because they were working with T6 material and assumed a higher-strength designation implied different mass. It doesn’t.

Density of Aluminum in lb/in³ — Settling the 0.0975 vs. 0.1 Confusion

I want to spend a moment on this because I’ve watched it cause real, compounding errors in procurement.

Many references — textbooks, supplier sites, quick-reference tables — quote aluminum density as 0.1 lb/in³. Some quote 0.0975 lb/in³. Which is correct?

The exact conversion from 2,699 kg/m³:

2,699 kg/m³ × 0.000036127 lb/in³ per kg/m³ = 0.09752 lb/in³

Round to four significant figures: 0.0975 lb/in³.

The value 0.1 lb/in³ is a rounded approximation — specifically, it’s rounded to one significant figure. That’s a 2.5% overestimate.

For a single part, 2.5% is negligible. It’s not negligible at scale.

Early in my career, I worked alongside a purchasing coordinator who used 0.1 lb/in³ to estimate freight weight for recurring pallet shipments of 6061 brackets. The pallets were heavy enough that the overestimate pushed a shipment into a higher freight class. Over a 50,000-part annual order, the freight quotes were built on phantom weight. When we caught it, the correction to 0.0975 dropped the estimated freight class and saved the customer a meaningful amount on an already thin-margin contract. I’ve used 0.0975 ever since. So should you.

The rule: Use 0.0975 lb/in³ for calculations. Use 0.1 lb/in³ only for back-of-envelope mental math where one decimal place is sufficient.

How Temperature Affects Aluminum Density

Every article on this topic gives you the room-temperature value and stops. Temperature effects are real and occasionally matter — so here’s the complete picture.

The coefficient of thermal expansion governs it

Aluminum has a coefficient of linear thermal expansion of approximately 23.6 μm/(m·°C) — nearly twice that of steel (~11.7 μm/(m·°C)). Volumetric expansion is roughly three times the linear coefficient:

Volumetric expansion coefficient ≈ 3 × 23.6 = 70.8 μm/(m³·°C)

At 100°C relative to 20°C (an 80°C rise):

Volume increase ≈ 80 × 70.8 × 10⁻⁶ = 0.566%

Density decrease ≈ 0.57%

2,700 kg/m³ at 20°C → approximately 2,685 kg/m³ at 100°C

When this actually matters in practice

For static weight calculations — shipping, structural loading, part weight on a drawing — it doesn’t matter. Use the room-temperature value.

For precision machining, the concern is dimensional change from heat buildup during cutting, not density change. A 300 mm aluminum part heated to 80°C above ambient grows by approximately 0.57 mm across its length. That’s what our CNC operators watch, not the density shift.

For laser cutting aluminum guide: the heat-affected zone in aluminum is extremely narrow — typically less than 0.3 mm with nitrogen assist — and the bulk material temperature barely changes. Density at the material level is unaffected.

For die casting and foundry work, liquid aluminum at approximately 700°C has a density of around 2,380 kg/m³ — a 12% reduction from the solid value. This matters for mold fill calculations and is the reason casting yield is calculated differently from machined-part weight.

Aluminum Density and International Grade Designations

If you work with European or Asian supply chains, you’ve encountered aluminum alloy designations that don’t look like the US 4-digit system. The density values are identical to the US equivalents, but finding the right number requires knowing the mapping.

European (EN/DIN) aluminum designations

European aluminum alloys use the EN AW-XXXX system under EN 573. The four-digit number maps to the same Aluminum Association series structure, so the density tables above still apply.

Source: Michael Smith Engineers Grade Comparison Table (DIN/BS/USA/Japan); Aluminum Association.

EN AW-6082 is the most common source of confusion. European structural drawings frequently specify 6082 rather than 6061. The compositions differ slightly — 6082 has higher manganese and lower copper — but the density is the same, 2,700 kg/m³. If a European drawing lands on your desk with EN AW-6082 specified and you need a weight calculation, use 2,700. If you need to source it in North America, the nearest available grade is 6061.

Density of Aluminum vs. Steel — The Honest Comparison for Part Designers

The “aluminum is 1/3 the weight of steel” statement is true for equal volumes. But product designers usually need to compare materials for equal function, not equal volume — and that’s a more nuanced calculation.

The weight saving for equal geometry

Take a common laser-cut bracket: 200 mm × 150 mm × 5 mm.

We recently completed a project for a customer building drone chassis frames. They had been producing the panels from 3 mm A36 laser-cut steel. When they asked us to re-quote in 6061-T6, here’s what the numbers looked like:

• Panel size: 250 × 180 × 4 mm, 48 panels per assembly
• Steel panel weight: 1.41 kg → assembly weight: 67.7 kg
• Aluminum panel weight: 0.486 kg → assembly weight: 23.3 kg
• Weight saved per assembly: 44.4 kg

The density difference — 7,850 vs. 2,700 kg/m³ — was directly worth 44 kg per unit in their payload budget. That’s not abstract. That’s the difference between a drone that barely lifts off and one with meaningful operational range.

When density alone isn’t enough — the specific strength argument

Aluminum’s lower density doesn’t automatically mean the part will be lighter if the design must be resized to maintain structural performance.

The correct metric for structural comparisons is specific strength (tensile strength divided by density):

6061-T6 delivers approximately 2.25× the specific strength of A36. This means for a load-bearing application, you can often use a lighter aluminum section and still meet the load requirement — the weight saving goes beyond the raw density ratio.

The honest limitation: Aluminum has significantly lower stiffness than steel. Young’s modulus for aluminum is approximately 69 GPa vs. 200 GPa for steel. If your design is governed by deflection rather than strength — think long unsupported spans, thin-gauge panels under bending loads — a substitution to aluminum at equal weight may fail the stiffness requirement. In those cases, you need to increase the section thickness or add geometry (ribs, flanges), which eats into the weight savings.

This is the part most material-selection articles don’t say. We encounter it regularly with customers converting steel enclosures to aluminum for weight reasons, only to discover the cover panel deflects visibly under hand pressure. Density tells you the mass. Modulus tells you the stiffness. You need both numbers to make a good material decision.

Five Mistakes Engineers Make With Aluminum Density

These come from watching jobs go wrong — or catching them before they do.

Mistake 1: Using steel density for an aluminum part. It happens when engineers switch materials mid-project and forget to update the density field. The weight calculation is off by nearly 3×. We’ve received drawings marked “aluminum” with weight callouts that were clearly calculated at 7,850 kg/m³.

Mistake 2: Using 2,700 kg/m³ for 7075. For most jobs, the error is small. For 7075-T6 aerospace brackets where the customer is tracking every gram, using 2,700 instead of 2,810 undercalculates part weight by 4%. On a 20-part assembly that’s meaningful.

Mistake 3: Using 0.1 lb/in³ for freight calculations. As described above: the correct value is 0.0975. The 0.1 figure is a one-decimal-place approximation. On small jobs it doesn’t matter. On high-volume, weight-sensitive freight, it adds up.

Mistake 4: Assuming cast and wrought aluminum have the same measured density. We occasionally handle components cast in AlSi10Mg with a theoretical density of approximately 2,680 kg/m³. When we measure density on actual cast parts using the water displacement method, we typically get 2,580–2,640 kg/m³. Micro-porosity in the casting accounts for the gap — sometimes 2–5%. If you’re designing a lifting fixture for a large cast aluminum housing and you use the theoretical value, you’re underestimating actual weight. For a 10 kg part the error is irrelevant. For a 200 kg hydraulic housing that goes on a crane, it matters.

Mistake 5: Confusing density with specific gravity. Specific gravity for aluminum is 2.70 — dimensionless, the ratio of aluminum’s density to water’s density (1,000 kg/m³). The number looks identical to the g/cm³ value. Engineers sometimes plug specific gravity where the formula expects g/cm³, or vice versa. The calculation is identical because 1 g/cm³ = 1,000 kg/m³ and water’s density is 1.0 g/cm³ = 1,000 kg/m³. But the units are different, and dimensional analysis breaks if you’re not careful.

Frequently Asked Questions About the Density of Aluminum

Q: What is the density of aluminum in g/cm³?

The density of aluminum is 2.70 g/cm³. This is the Aluminum Association standardized value for pure aluminum (1xxx series) at room temperature. Commercial alloys in the 6xxx series (6061, 6063) share this value. Copper-rich 2xxx and zinc-rich 7xxx alloys are slightly higher.

Q: What is the density of aluminum in kg/m³?

2,700 kg/m³. This is the standard SI value for pure aluminum and is appropriate for most engineering calculations involving 1xxx and 6xxx series alloys. For 7075, use 2,810 kg/m³; for 2024, use 2,780 kg/m³.

Q: What is the density of aluminum in lb/in³?

0.0975 lb/in³ — not 0.1. Many references round to 0.1, but the correct conversion from 2,699 kg/m³ is 0.09752 lb/in³. Use 0.0975 for all calculations. Reserve 0.1 for rough mental math only.

Q: Is aluminum density the same for all alloys?

No. The range across commercial alloys is approximately 2,640 to 2,810 kg/m³. The dominant factor is alloying elements: copper and zinc increase density; silicon and magnesium decrease it. For most laser-cut sheet and plate work in 1xxx, 3xxx, and 6xxx series, 2,700 kg/m³ is correct. Check alloy-specific values for 2xxx and 7xxx series work.

Q: Does heat treatment or temper change aluminum density?

No. 6061-O, 6061-T4, and 6061-T6 all have a density of 2,700 kg/m³. Temper affects microstructure and mechanical properties — yield strength varies from 55 MPa to 276 MPa across those three conditions — but it does not change mass per unit volume.

Q: What is the density of 6061 aluminum?

2,700 kg/m³ (2.70 g/cm³, 0.0975 lb/in³) — identical to pure aluminum. 6061’s principal alloying elements are magnesium (slightly less dense than aluminum) and silicon (also slightly less dense), so the net effect on density is negligible.

Q: What is the density of 7075 aluminum?

2,810 kg/m³ (2.81 g/cm³, 0.102 lb/in³). 7075 contains 5.1–6.1% zinc, which has a density of 7,133 kg/m³ — more than 2.6× that of aluminum. The zinc addition measurably increases the alloy’s density relative to the 6xxx series.

Q: How does aluminum density compare to stainless steel?

304 stainless steel has a density of 7,930 kg/m³. Aluminum at 2,700 kg/m³ is 34% the density of stainless, meaning an aluminum part of the same geometry weighs roughly one-third as much. For equal structural performance, the comparison is more favorable to aluminum: 6061-T6 has approximately 2.25× the specific strength (strength-to-weight ratio) of A36 carbon steel and broadly similar specific strength to 304 stainless.

References

1. Aluminum Association, Aluminum Standards and Data, current edition. (Standardized density values by alloy designation; physical property data for all series.)
2. ASM Handbook, Volume 1: Properties and Selection — Irons, Steels, and High-Performance Alloys, 10th Edition. ASM International, 1990. (Physical and mechanical properties of wrought aluminum alloys; density data by alloy family.)
3. ASTM B209, Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate, ASTM International, current edition. (Procurement specification for the wrought aluminum flat products most commonly laser-cut and fabricated.)
4. Michael Smith Engineers Limited, Material Grade Comparison Table (DIN/BS/USA/Japan cross-reference), available at michaelsmithengineers.co.uk. (European EN AW designations and their US Aluminum Association equivalents, with density context.)
5. W.D. Callister Jr. and D.G. Rethwisch, Materials Science and Engineering: An Introduction, 10th Edition. Wiley, 2018. (FCC unit cell parameter and first-principles density derivation for aluminum; crystal structure data.)

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Dr. Liu Che

Dr. Liu Che holds a Ph.D. in Engineering from Dalian University of Technology and completed postdoctoral research at the Mechanical Engineering Postdoctoral Fellowship of Harbin Institute of Technology. His research focuses on core algorithms for large-scale laser equipment integration, laser cladding remanufacturing, and real-time intelligent monitoring systems for processing. He possesses profound academic expertise in cutting-edge fields such as laser beam spatial shaping and the mechanism analysis of laser processing of special alloys. He has led numerous solutions to technical challenges in cutting and surface modification of high-hardness materials in the heavy machinery industry, demonstrating strong theoretical foundations and outstanding engineering implementation capabilities.

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