Lightest Alloys by Density

20 alloys

Density — mass per unit volume — determines how heavy a component will be for a given size. In aerospace, automotive, and portable electronics, lighter alloys translate directly into fuel savings, longer range, and better ergonomics. The lightest structural alloys are magnesium-based, with densities below 1.9 g/cm³ — roughly one-quarter the density of steel.

Aluminum alloys dominate the middle ground at 2.6–2.9 g/cm³, offering an excellent balance of strength, corrosion resistance, and manufacturability. Titanium alloys, though denser at 4.4–4.5 g/cm³, deliver strength-to-weight ratios that rival or exceed aluminum in high-performance applications.

This ranking lists alloys in ascending order of density, highlighting the lightest options available to engineers. Tensile strength and metal base are shown alongside density so you can quickly identify alloys that combine low weight with adequate structural performance.
How we ranked these

Ranked by density in g/cm³ (ascending — lightest first). Values from manufacturer datasheets and ASM International. Only alloys with measured density values are included.

🥇 #1
MPEA Al0.312 Ca0.021 Li0.792 Mg1 Si0.021
MPEA Al0.312 Ca0.021 Li0.792 Mg1 Si0.021

High-Entropy Alloy (MPEA) · Other

High-entropy alloy. Phase: other. Processing: CAST.

1.40 g/cm³ Other
See details
🥈 #2
MPEA Al0.333 Ca0.011 Li0.844 Mg1 Si0.033
MPEA Al0.333 Ca0.011 Li0.844 Mg1 Si0.033

High-Entropy Alloy (MPEA) · Other

High-entropy alloy. Phase: other. Processing: CAST.

1.40 g/cm³ Other
See details →
🥉 #3
MPEA Al0.429 Ca0.286 Li1 Mg1 Si0.143
MPEA Al0.429 Ca0.286 Li1 Mg1 Si0.143

High-Entropy Alloy (MPEA) · Other

High-entropy alloy. Phase: other. Processing: CAST.

1.40 g/cm³ Other
See details →
  1. MPEA Al0.333 Ca0.011 Li0.867 Mg1 Si0.011
    MPEA Al0.333 Ca0.011 Li0.867 Mg1 Si0.011

    High-Entropy Alloy (MPEA) · Other

    High-entropy alloy. Phase: other. Processing: CAST.

    1.40 g/cm³ Other
    See details →
  2. MPEA Al0.569 Ca0.143 Li0.857 Mg1 Si0.286 Y0.003
    MPEA Al0.569 Ca0.143 Li0.857 Mg1 Si0.286 Y0.003

    High-Entropy Alloy (MPEA) · Other

    High-entropy alloy. Phase: other. Processing: CAST.

    1.60 g/cm³ Other
    See details →
  3. MPEA Al0.667 Li0.667 Mg0.333 Sc0.667 Ti1
    MPEA Al0.667 Li0.667 Mg0.333 Sc0.667 Ti1

    High-Entropy Alloy (MPEA) · Titanium

    High-entropy alloy. Phase: other. Processing: .

    2.70 g/cm³ Titanium
    See details →
  4. MPEA Al1 Li0.5 Mg1 Sn0.2 Zn0.5
    MPEA Al1 Li0.5 Mg1 Sn0.2 Zn0.5

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: CAST.

    2.90 g/cm³ 546 MPa Aluminum
    See details →
  5. MPEA Al1 Cu0.062 Li0.062 Mg0.062 Zn0.062
    MPEA Al1 Cu0.062 Li0.062 Mg0.062 Zn0.062

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: CAST.

    2.90 g/cm³ 879 MPa Aluminum
    See details →
  6. MPEA Al1 Li0.062 Mg0.062 Sn0.062 Zn0.062
    MPEA Al1 Li0.062 Mg0.062 Sn0.062 Zn0.062

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: CAST.

    3.00 g/cm³ 836 MPa Aluminum
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  7. MPEA Al1 Cr0.077 Cu0.077 Mg0.077 Si0.231 Zn0.077
    MPEA Al1 Cr0.077 Cu0.077 Mg0.077 Si0.231 Zn0.077

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: FCC. Processing: CAST.

    3.10 g/cm³ Aluminum
    See details →
  8. MPEA Al1 Cu0.077 Fe0.077 Mg0.077 Si0.231 Zn0.077
    MPEA Al1 Cu0.077 Fe0.077 Mg0.077 Si0.231 Zn0.077

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: FCC. Processing: CAST.

    3.20 g/cm³ Aluminum
    See details →
  9. MPEA Al1 Cu0.077 Mg0.077 Mn0.077 Si0.231 Zn0.077
    MPEA Al1 Cu0.077 Mg0.077 Mn0.077 Si0.231 Zn0.077

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: FCC. Processing: CAST.

    3.20 g/cm³ Aluminum
    See details →
  10. MPEA Al1 Cu0.077 Mg0.077 Si0.231 Zn0.077 Zr0.077
    MPEA Al1 Cu0.077 Mg0.077 Si0.231 Zn0.077 Zr0.077

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: CAST.

    3.20 g/cm³ Aluminum
    See details →
  11. MPEA Al1 Cu0.077 Mg0.077 Ni0.077 Si0.231 Zn0.077
    MPEA Al1 Cu0.077 Mg0.077 Ni0.077 Si0.231 Zn0.077

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: FCC. Processing: CAST.

    3.20 g/cm³ Aluminum
    See details →
  12. MPEA Al1 Li1 Mg1 Sn1 Zn1
    MPEA Al1 Li1 Mg1 Sn1 Zn1

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: CAST.

    3.90 g/cm³ 615 MPa Aluminum
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  13. MPEA Al1 Co0.255 Cr0.426 Cu0.106 Fe0.234 Ni0.106
    MPEA Al1 Co0.255 Cr0.426 Cu0.106 Fe0.234 Ni0.106

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: .

    5.00 g/cm³ Aluminum
    See details →
  14. MPEA Al1 Co0.234 Cr0.468 Cu0.106 Fe0.213 Ni0.106
    MPEA Al1 Co0.234 Cr0.468 Cu0.106 Fe0.213 Ni0.106

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: .

    5.00 g/cm³ Aluminum
    See details →
  15. MPEA Al1 Co0.277 Cr0.426 Cu0.106 Fe0.213 Ni0.106
    MPEA Al1 Co0.277 Cr0.426 Cu0.106 Fe0.213 Ni0.106

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: .

    5.00 g/cm³ Aluminum
    See details →
  16. MPEA Al1 Co0.298 Cr0.404 Cu0.106 Fe0.213 Ni0.106
    MPEA Al1 Co0.298 Cr0.404 Cu0.106 Fe0.213 Ni0.106

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: .

    5.10 g/cm³ Aluminum
    See details →
  17. MPEA Al1 Co0.298 Cr0.319 Cu0.106 Fe0.277 Ni0.128
    MPEA Al1 Co0.298 Cr0.319 Cu0.106 Fe0.277 Ni0.128

    High-Entropy Alloy (MPEA) · Aluminum

    High-entropy alloy. Phase: other. Processing: .

    5.10 g/cm³ Aluminum
    See details →

Frequently Asked Questions

What is the lightest structural alloy?
Magnesium alloys are the lightest structural metals, with densities below 1.9 g/cm³ — roughly 35% lighter than aluminum and 78% lighter than steel. They are used in laptop cases, automotive steering columns, and aerospace brackets.
Why is density important in engineering?
Lower density means less weight for the same volume. In aerospace, every kilogram saved translates to fuel savings over the aircraft's lifetime. In automotive, lighter vehicles improve fuel efficiency and reduce emissions.
Can light alloys be strong enough for structural use?
Yes. Advanced aluminum-lithium alloys and high-strength magnesium alloys achieve strength-to-weight ratios that rival or exceed many steels. Titanium alloys, though denser, offer exceptional specific strength for critical aerospace components.

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