Density of Aluminum: 2,700 kg/m³ — Alloys, Comparisons, and Weight Estimates
Pure aluminum has a density of 2,700 kg/m³ (2.70 g/cm³), making it one of the most widely used lightweight metals in engineering. Its density is roughly one-third that of steel, which is why it is common in aircraft, vehicles, and consumer electronics.
Aluminum alloy grades vary slightly because copper, zinc, magnesium, and other elements change the final composition, typically across 2,600–2,900 kg/m³. This page gives pure aluminum and major alloy density values, compares aluminum with steel, and shows practical weight estimates using the material density calculator.
Key values
Aluminum Density: Key Values
kg/m³
2,700 kg/m³
Pure aluminum at room temperature
g/cm³
2.70 g/cm³
Standard reference value
lb/ft³
168.6 lb/ft³
U.S. engineering reference
Values are for commercially pure aluminum (1100 series, 99%+ Al) at 20°C.
Most structural aluminum alloys fall between 2,600 and 2,900 kg/m³.
Alloys
Aluminum Alloy Density by Grade
Pure aluminum is rarely used in engineering because its strength is relatively low. Adding copper, zinc, magnesium, silicon, and other alloying elements greatly improves strength, while density usually changes by less than ±5%.
Even at the denser end of the alloy range, aluminum remains far lighter than steel.
| Alloy | Series | Key Elements | Density | Typical Use |
|---|---|---|---|---|
| 1100 | 1xxx | 99%+ Al (pure) | 2,710 kg/m³ | Chemical equipment, foil |
| 2024 | 2xxx | Cu 4.4%, Mg 1.5% | 2,780 kg/m³ | Aircraft structures |
| 3003 | 3xxx | Mn 1.2% | 2,730 kg/m³ | Cookware, roofing |
| 5052 | 5xxx | Mg 2.5%, Cr 0.25% | 2,680 kg/m³ | Marine, pressure vessels |
| 6061 | 6xxx | Mg 1.0%, Si 0.6% | 2,700 kg/m³ | Structural, most common alloy |
| 6063 | 6xxx | Mg 0.7%, Si 0.4% | 2,690 kg/m³ | Extrusions, window frames |
| 7075 | 7xxx | Zn 5.6%, Mg 2.5% | 2,810 kg/m³ | High-strength aerospace |
| 7068 | 7xxx | Zn 7.2%, Mg 2.3% | 2,850 kg/m³ | Ultra-high-strength aerospace |
6061 is the most widely used structural aluminum alloy. Its density of 2,700 kg/m³ is essentially the same as pure aluminum, making it the default reference value in most engineering calculations.
Atomic mass
Why Is Aluminum Less Dense Than Steel?
The most fundamental reason is atomic mass. An aluminum atom has a mass of about 27 atomic mass units (u), while an iron atom (the primary component of steel) has a mass of about 56 u — more than twice as heavy. Even before considering how the atoms pack together, iron atoms are simply much heavier than aluminum atoms. For the general relationship between mass, volume, and material density, see what is density.
Both aluminum and iron adopt face-centered cubic (FCC) or body-centered cubic (BCC) crystal structures with similar packing efficiencies. The packing geometry is not the main driver of the density difference — atomic mass is. Iron's heavier atoms, packed at similar densities, produce a much denser material.
This means that for the same volume, a steel component weighs about 2.9 times more than an aluminum one. In weight-sensitive applications — aircraft fuselages, car body panels, bicycle frames, laptop enclosures — replacing steel with aluminum alloy can cut component weight by roughly two-thirds while retaining adequate strength when the right alloy and geometry are chosen.
Structural comparison
Density of Aluminum vs Other Structural Materials
Aluminum sits in the lightweight range among common structural materials: lighter than steel, copper, and titanium, but heavier than carbon fiber composites and magnesium alloys.
| Material | Density (kg/m³) | vs Aluminum | Notes |
|---|---|---|---|
| Carbon fiber composite | 1,550 kg/m³ | 43% lighter | CFRP typical value |
| Magnesium alloy | 1,770 kg/m³ | 34% lighter | Lightest structural metal |
| Aluminum 6061 | 2,700 kg/m³ | — | Reference |
| Titanium (pure) | 4,500 kg/m³ | 67% heavier | High strength-to-weight; see density of titanium |
| Steel (carbon) | 7,850 kg/m³ | 191% heavier | Standard structural metal; see density of steel |
| Copper | 8,960 kg/m³ | 232% heavier | Electrical applications; see density of copper |
| Lead | 11,340 kg/m³ | 320% heavier | Shielding and ballast |
For broader material comparisons, open the density table.
Examples
Aluminum Weight Estimation: Practical Examples
Using aluminum density lets you estimate part weight quickly before machining or purchasing material.
Example 1 — Aluminum sheet weight
An aluminum sheet measuring 2 m × 1 m × 3 mm thick (6061 alloy):
Volume = 2 × 1 × 0.003 = 0.006 m³
Mass = 2,700 × 0.006 = 16.2 kg
Same sheet in steel: 7,850 × 0.006 = 47.1 kg — 2.9× heavier.
Example 2 — Aluminum extrusion weight
A 6063 aluminum extrusion 6 m long with a cross-section area of 800 mm²:
Volume = 0.0008 × 6 = 0.0048 m³
Mass = 2,690 × 0.0048 = 12.9 kg
Example 3 — Aluminum vs steel for a bicycle frame
A simplified frame volume of 0.0012 m³:
Aluminum (6061): 2,700 × 0.0012 = 3.24 kg
Steel (chromoly): 7,850 × 0.0012 = 9.42 kg
Aluminum saves about 6.2 kg — roughly two-thirds of the frame weight.
Calculate Aluminum Mass or Volume
Material Density Calculator
Select aluminum or any of 232 materials and solve for mass or volume instantly. Supports custom density input for specific alloy grades.
Density of Steel
Compare aluminum against steel grades side by side, with worked weight estimation examples for plates, rods, and structural sections.
FAQ
Frequently Asked Questions
What is the density of aluminum in kg/m³?
Pure aluminum has a density of 2,700 kg/m³ at room temperature. The most common structural alloy, 6061, has essentially the same density. Higher-strength alloys like 7075 are slightly denser at 2,810 kg/m³ due to their higher zinc and copper content.
What is the density of aluminum in g/cm³?
The density of aluminum is 2.70 g/cm³ for pure aluminum and most 6xxx series alloys. This is the value most commonly cited in chemistry and materials science references. For comparison, steel is 7.85 g/cm³ — about 2.9 times denser.
Why is aluminum so much lighter than steel?
The primary reason is atomic mass. Aluminum atoms weigh about 27 atomic mass units, while iron atoms (the main component of steel) weigh about 56 u — more than twice as much. Both metals have similar crystal packing efficiencies, so the heavier iron atoms produce a much denser material at the same packing geometry.
What is the density of 6061 aluminum?
Aluminum 6061 has a density of 2,700 kg/m³ (2.70 g/cm³), essentially the same as pure aluminum. It is the most widely used structural aluminum alloy, combining good strength, weldability, and corrosion resistance with the weight advantage of aluminum.
What is the density of 7075 aluminum?
Aluminum 7075 has a density of approximately 2,810 kg/m³ (2.81 g/cm³), slightly higher than 6061 due to its higher zinc content (about 5.6%). It is one of the strongest aluminum alloys and is widely used in aerospace and high-performance applications where strength-to-weight ratio is critical.
Is aluminium the same as aluminum?
Yes. Aluminium (British and international spelling) and aluminum (American spelling) refer to the same element, atomic number 13. The density values are identical regardless of spelling convention: 2,700 kg/m³ for the pure metal.