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Which is least dense: aluminum, titanium, or iron?

Aluminum, at roughly 0.10 pound per cubic inch in this comparison.

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  1. Titanium
  2. Aluminum ✔
  3. Iron

Why: Aluminum is the lightest by volume of these three. Titanium sits between aluminum and iron, so an equal-size titanium part weighs about 60 percent more than an aluminum one.

Huh, didn't know that: Low density matters most when engineers compare parts that can be redesigned to exploit a material's strength.

The dad joke
Aluminum entered the lightweight contest and barely tipped the scale.
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References

Answer: Aluminum. Aluminum is the lightest by volume of these three. Titanium sits between aluminum and iron, so an equal-size titanium part weighs about 60 percent more than an aluminum one.

  1. NASA Titanium and Titanium Alloys ntrs.nasa.gov/api/citations/19660015718/downloads/19660015718.pdf
    The density of titanium is about 0.16 lb/cu in. as compared with 0.10 for aluminum and 0.28 for iron.
    Checked 2026-10-10.

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