Density of Titanium Metal: The Numbers, the Nuances, and How to Use Them Correctly

On a recent project, a team quoted a titanium plate job using 4.50 g/cm³ for titanium’s density. The drawing review used 4.51 g/cm³. Nothing “mystical” happened—just a small mismatch in assumptions. But after multiplying that tiny difference across a large batch (and adding machining allowance), the weight estimate drifted enough to trigger a pricing recheck and a delivery discussion nobody wanted.

This article is here to prevent that kind of avoidable friction. You’ll get the commonly accepted density of titanium metal, the correct unit conversions, and—more importantly—clear rules for which density value to use in design calculations, purchasing, inspection, and additive manufacturing.

The headline value: titanium’s density at room temperature

For commercially pure titanium at room temperature, a widely cited density is about 4.51 g/cm³ (which equals 4510 kg/m³).

If you’ve seen 4.50 g/cm³ instead, that is often just rounding (or a different reference convention). In engineering communication, what matters is not winning the “last decimal” debate—it’s stating the conditions so your colleagues, suppliers, and customers can reproduce your calculation.

Pure titanium vs common titanium alloys (Grade 2, Grade 5)

“Titanium metal” in search results usually means elemental/commercially pure Ti. In real procurement, you may be using a grade (e.g., ASTM Grade 2) or an alloy (e.g., Grade 5 / Ti-6Al-4V). Alloys can shift density slightly because alloying elements have their own densities and alter lattice parameters.

As a practical rule:

• Commercially pure titanium: ~4.51 g/cm³ (typical reference value at room temperature).
• Ti-6Al-4V (Grade 5): commonly listed around ~4.43 g/cm³ in many engineering datasheets (varies by source and specification context; always confirm with your supplier’s datasheet/MTC).

When I write specifications, I avoid locking a project into a single “universal” density number for all titanium products. Instead, I specify the grade/alloy + standard + test/assumption.

Unit conversions you’ll actually use (g/cm³, kg/m³, lb/in³)

Unit	Conversion from 4.51 g/cm³	Notes
g/cm³	4.51	Common in datasheets and classrooms
kg/m³	4510	Multiply g/cm³ by 1000
lb/in³	~0.163	Useful in US machining quotes; depends on rounding

Recommended “safe” citation format (prevents 4.50 vs 4.51 arguments):
“Density (commercially pure Ti, ~room temperature): ≈4.51 g/cm³ (≈4510 kg/m³), value referenced from the Royal Society of Chemistry periodic table entry for Titanium. Use grade-specific values when applicable.”

Authority note: The RSC provides an accessible, citable baseline value for elemental titanium. For deeper property datasets and verification pathways, the NIST Chemistry WebBook is a respected reference hub. (You’ll still want grade-level datasheets for alloys.)

Why different sources show different titanium density values

Different density values are usually not “contradictions.” They’re different assumptions. In practice, four factors explain most discrepancies.

1) Rounding (and the psychology of “nice” numbers)

Some references publish densities to two decimals; others round to one. If one site shows 4.50 and another shows 4.51, they may be describing the same physical reality with different rounding conventions.

2) Reference temperature (density is not temperature-invariant)

Metals expand when heated. If volume increases while mass stays the same, density decreases. Many casual pages omit the reference temperature entirely, even though engineering work often assumes “room temperature” (commonly 20°C, but not always explicitly stated).

If your application spans large temperature ranges, don’t treat density as a constant. A simple way to estimate the trend is to account for volumetric expansion using the coefficient of thermal expansion (CTE). For small temperature changes, density roughly follows:

ρ(T) ≈ ρ(T₀) / (1 + 3αΔT)

Where α is the linear CTE and ΔT is the temperature change. This is an approximation, but it’s often more meaningful than arguing about 0.01 g/cm³ at “room temperature.”

3) Composition and grade (pure Ti vs alloys vs “impurities”)

Commercially pure titanium is not a lab-perfect single isotope crystal. Real products have controlled chemistry ranges (including interstitials like oxygen) that influence mechanical properties and can slightly affect density. Alloys (Ti-6Al-4V, Ti-3Al-2.5V, etc.) legitimately have different densities.

4) Porosity and processing route (cast, forged, PM, AM)

This is the big one that many density articles ignore: the density you measure on a real part can be lower than the theoretical density if the material contains pores (from casting, powder metallurgy, or additive manufacturing), or if measurement method struggles with surface-connected voids.

A 3-step “density alignment” workflow (use this in design reviews and purchasing):

1. State the material identity: CP Ti or alloy? Which grade/spec (e.g., ASTM grade)?
2. State the density type: theoretical density (chemistry-based) vs measured (Archimedes/pycnometry/CT).
3. State the conditions: reference temperature, measurement method (if measured), and whether porosity is expected/allowed.

How to calculate titanium weight from dimensions (with worked examples)

Core formula: Weight (mass) = Volume × Density

Pick a density value consistent with your grade and assumptions. For quick estimating of commercially pure titanium at room temperature, many engineers use ρ = 4.51 g/cm³ (or 4510 kg/m³).

Example 1: Weight of a titanium round bar (from diameter and length)

Suppose you have a titanium bar:

• Diameter D = 20 mm
• Length L = 1.0 m
• Density (assumed CP Ti): ρ = 4510 kg/m³

Convert to meters: D = 0.02 m, radius r = 0.01 m.

Volume of cylinder: V = πr²L = π × (0.01)² × 1.0 ≈ 3.1416×10⁻⁴ m³

Mass: m = Vρ ≈ 3.1416×10⁻⁴ × 4510 ≈ 1.42 kg

Result: A 20 mm × 1 m titanium bar is about 1.42 kg (for CP Ti at room temperature). If it’s Ti-6Al-4V, the result will be slightly lower using an alloy-appropriate density.

Example 2: Weight of a titanium plate (from length × width × thickness)

• Length: 1000 mm (1.0 m)
• Width: 500 mm (0.5 m)
• Thickness: 10 mm (0.01 m)

Volume: V = 1.0 × 0.5 × 0.01 = 0.005 m³

Mass: m = 0.005 × 4510 = 22.55 kg

A quick “procurement-friendly” method you can turn into a spreadsheet

If your team often quotes bars and plates, build a sheet with:

• Input: dimensions (mm), quantity
• Auto-conversion to meters
• Selectable density dropdown by grade/alloy
• Output: mass per piece, total mass
• Notes column: “density basis” (theoretical vs measured, temperature)

Common failure mode: mixing mm and m without conversion. In my experience, this causes far more error than choosing 4.50 vs 4.51.

Titanium vs aluminum vs steel: what density does (and doesn’t) tell you

Density is a powerful first filter, but it is not a complete selection method.

Density ratios (the “back of the napkin” comparison)

• Titanium (CP): ~4.51 g/cm³
• Aluminum (pure; many alloys near this): ~2.70 g/cm³
• Steel (typical carbon steels): ~7.85 g/cm³

So, at equal volume:

• Titanium is about ~40–45% lighter than steel (4.51 vs 7.85).
• Titanium is about ~65–70% heavier than aluminum (4.51 vs 2.70).

What density misses: stiffness and “design reality”

Many people hear “titanium is lightweight” and assume it always makes parts lighter. Not necessarily.

• Strength-driven designs: Titanium’s high strength can allow thinner sections, so the finished part can be lighter even if titanium is denser than aluminum.
• Stiffness-driven designs: If deflection limits dominate, elastic modulus matters a lot. Titanium’s modulus is lower than steel’s, so you may need thicker geometry to hit stiffness targets, which reduces the “density advantage.”
• Cost & manufacturability: Density doesn’t tell you machining cost, scrap rate, or lead time.

Density in powders and additive manufacturing: true density, apparent density, relative density

If you work with titanium powder or additive manufacturing (AM), “density” becomes a family of metrics—not a single number.

Three density terms you should not mix

• True (theoretical) density: Density of the solid material with no pores (chemistry and crystal structure basis).
• Apparent/bulk density (powder): Includes the voids between powder particles; useful for powder handling and recoating behavior, not for part mass prediction by itself.
• Relative density (part quality metric): measured density / theoretical density.

The practical math: relative density and porosity (quick estimate)

Relative density: RD = ρ_measured / ρ_theoretical

A commonly used first-order approximation links porosity fraction (P) to relative density:

P ≈ 1 − RD

Example: If a titanium AM coupon measures RD = 0.99, then P ≈ 1%. That may or may not be acceptable depending on application, fatigue requirements, inspection method, and customer specification—but at least everyone can discuss it using the same language.

Boundary conditions (important):

• This approximation treats pores as “missing volume” and ignores complex pore shapes and measurement artifacts.
• If your method underestimates volume because surface-connected pores trap bubbles (Archimedes), RD can be biased.
• For critical applications, you’ll often combine density with microscopy/CT and mechanical testing.

How to measure titanium density (and avoid common errors)

Two labs can measure the “same” titanium sample and get different results if they don’t control the details. The goal is not perfection—it’s repeatability and method transparency.

Archimedes method: a practical checklist

The Archimedes method measures density via buoyancy, using mass in air and apparent mass in a fluid (often water). It’s widely used because it’s accessible and fast.

• Clean the sample: oils and residues change wetting and trap bubbles.
• Control water temperature: water density changes with temperature; note it or use a standard condition.
• Reduce bubbles: agitate gently, use wetting agents if allowed by your procedure, and watch for bubbles clinging to rough surfaces.
• Surface roughness matters: rough AM surfaces can trap air; consider sealing, polishing, or switching method depending on your quality plan.
• Repeat measurements: take multiple readings and report average and spread.

When to consider helium pycnometry or CT (high-level guidance)

• Helium pycnometry: often used to measure true volume more reliably for porous materials (especially powders), because helium penetrates fine surface-connected pores better than water.
• CT scanning: provides pore morphology and distribution, not just a single density number—useful when fatigue or leak-tightness is critical.

Procurement & QA: how to specify density in a purchase order or inspection plan

Density disputes happen when a PO or drawing treats density as “obvious.” It’s not. Make it explicit.

What to put on drawings / POs (template-style wording)

• Material: “Titanium, Grade __, per ASTM __ (or ISO __).”
• Density basis for calculations (if needed): “Mass estimates based on density ___ at ~20°C (reference).”
• If density is an acceptance requirement: “Measured density by method ___; report relative density vs theoretical density for alloy ___.”
• Documentation: “Provide MTC/CoC including chemistry and mechanical properties per the specified standard.”

If you buy titanium mill products, you’ll often reference standards such as ASTM B348 (titanium and titanium alloy bars and billets) and ASTM B265 (titanium and titanium alloy strip, sheet, and plate). Even when the standard text is paywalled, citing the standard number aligns expectations across buyer and supplier.

Acceptance criteria: be careful with “density tolerance”

Unless you are in a powder/AM quality context, density is typically not used as a tight acceptance metric for wrought titanium products. If you try to enforce an overly strict “density tolerance” without specifying method and sample prep, you may create false rejects.

A better QA approach is:

• Use density as a calculation parameter for weight estimates and logistics.
• Use chemistry, mechanical tests, dimensions, and NDT as primary acceptance criteria per standard.
• For AM/PM parts where porosity is central, define relative density + method + sampling plan.

HonTitan support for titanium density and weight-critical projects

When weight drives cost, lead time, and compliance, small assumptions matter. HonTitan can help you align grade, standard, and density basis before you lock a quote or a drawing. If you share dimensions, target alloy (or application), and the spec you’re working to, we’ll support weight estimates, documentation (MTC/CoC), and clear communication so purchasing and engineering stay on the same page.

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