Density of Titanium: 4,507 kg/m³ — Alloys, Strength-to-Weight, and Applications

Pure titanium density varies slightly by grade: Grade 1 (CP-Ti, 4,510 kg/m³) through Grade 4 (4,510 kg/m³) are all commercially pure with minor impurity differences. Ti-6Al-4V (Grade 5), the most widely used alloy, is 4,430 kg/m³.

Titanium alloys are grouped into α, β, and α+β types by microstructure. Adding alloy elements usually lowers density slightly because aluminum (2,700 kg/m³) and vanadium (6,110 kg/m³) average below pure titanium, while greatly increasing strength.

Ti-6Al-4V (Grade 5) accounts for approximately 50% of all titanium alloy production worldwide. Its combination of 4,430 kg/m³ density and 950 MPa tensile strength gives it one of the highest strength-to-weight ratios of any structural metal.

For broader alloy and material comparisons, open the density table.

Density alone tells only half the story. To understand why titanium is difficult to replace in aerospace, strength and density must be considered together as specific strength: strength divided by density.

Ti-6Al-4V has a higher specific strength than both high-strength aluminum alloys and most structural steels. This means a titanium component can be made lighter than an equivalent steel part while matching or exceeding its load-bearing capacity. CFRP composites have higher specific strength but are anisotropic, more expensive to manufacture, and cannot be easily machined or welded.

Atomic mass: Titanium has an atomic mass of 47.9 atomic mass units (u), compared to iron's 55.8 u. Although the difference seems modest, it is compounded by crystal structure. Pure titanium at room temperature adopts a hexagonal close-packed (HCP) crystal structure (α-phase), which has a packing efficiency of about 74% — similar to iron's body-centered cubic (BCC) structure at ~68%. The lighter atomic mass is the dominant factor in titanium's lower density. For the base mass-per-volume concept, see what is density.

Phase transformation and density: Above 882°C, titanium transforms from the α-phase (HCP) to the β-phase (BCC). The β-phase is slightly less dense than the α-phase because BCC packing is less efficient than HCP. Beta-stabilising alloy elements (vanadium, molybdenum, chromium) retain some β-phase at room temperature, which is why β-rich alloys like Ti-10V-2Fe-3Al (4,650 kg/m³) are slightly denser than pure titanium despite containing lighter alloying elements — the structural change partially offsets the compositional effect.

Comparison with aluminum: Titanium (47.9 u) is about 1.77 times heavier per atom than aluminum (27.0 u), which is why titanium's density (4,507 kg/m³) is about 1.67 times that of aluminum (2,700 kg/m³). However, titanium's much higher strength means that a titanium structural component can often be made thinner and smaller than an aluminum equivalent, partially or fully recovering the weight penalty.