Density of 316 Stainless Steel: Grade Data vs 304 and 316L

The density of 316 stainless steel is 7,980 kg/m³. That is 50 kg/m³ more than 304 — a difference of 0.6% —, and it comes directly from one element: molybdenum.

I process 316 and 316L sheet and plate every week at ARCUSCNC. For most weight calculations, the 50 kg/m³ difference from 304 is a rounding correction, not an engineering decision. But understanding why 316 is denser than 304 — and why 316L, despite having less carbon, weighs the same as 316 — answers questions that come up constantly in specification work and freight planning.

This article provides the official density value for 316 stainless steel in all unit systems, the molybdenum chemistry behind that value, a full grade comparison with 304 and 316L, and ready-to-use weight tables for standard sheet sizes.

The Official Density of Stainless Steel 316: Values in All Units

The density of 316 stainless steel is documented in the ASM Handbook, Volume 1 and is consistent with ASTM A240/A240M-22 certified material test reports for UNS S31600.

The lb/in³ value rounds to 0.288 in US fabrication practice. Precisely: 7,980 × (1/0.453592) × (1/39.3701)³ = 0.28816 lb/in³.

Weight formula — SI: Weight (kg) = Length (m) × Width (m) × Thickness (mm) × 7.98

Weight formula — Imperial: Weight (lb) = Length (in) × Width (in) × Thickness (in) × 0.288

Worked example: A 500 mm × 300 mm × 4 mm 316 stainless blank: Weight = 0.500 × 0.300 × 4 × 7.98 = 4.79 kg

The same blank in 304: 0.500 × 0.300 × 4 × 7.93 = 4.76 kg — 0.03 kg less. At the single-part level, the density difference between 304 and 316 is irrelevant. Across a large assembly or a full freight pallet, it accumulates.

For data source, please refer to the Metal Density Chart.

Why 316 Stainless Steel Density Is Higher Than 304 — The Molybdenum Effect

The density difference between 316 and 304 stainless steel is due to the addition of molybdenum.

Per ASTM A240/A240M-22, Table 1:

Molybdenum has a density of 10,280 kg/m³ — approximately 30% denser than iron (7,874 kg/m³) and 23% denser than nickel (8,908 kg/m³). When 2–3% molybdenum dissolves in an iron-chromium-nickel matrix, it pulls the alloy density upward.

Alongside the Mo addition, 316 also carries a higher nickel floor than 304: minimum 10.0% Ni vs. minimum 8.0% for 304. Nickel at 8,908 kg/m³ is also denser than iron. The higher minimum Ni in 316 adds a secondary upward pull on density.

Quantifying the density contribution from molybdenum

Using a simplified rule-of-mixtures for the difference between 304 and 316 at their nominal mid-range compositions:

Approximate 304 mid-range: 81% Fe + 19% Cr + 9.5% Ni (ignoring minor elements). Approximate 316 mid-range: 74% Fe + 17% Cr + 12% Ni + 2.5% Mo

Mo contribution: 2.5% × (10,280 − 7,874) = 2.5% × 2,406 = +60 kg/m³ from replacing iron with Mo Additional Ni contribution (12% vs. 9.5%): 2.5% × (8,908 − 7,874) = 2.5% × 1,034 = +26 kg/m³ Cr reduction (17% vs. 19%): −2% × (7,874 − 7,190) = −2% × 684 = −14 kg/m³ Net estimated increase: 60 + 26 − 14 = +72 kg/m³

The measured difference (7,980 − 7,930 = 50 kg/m³) is somewhat below the rule-of-mixtures estimate because solid solution atomic volume effects mean the alloy density is not perfectly additive. But the calculation confirms the direction and approximate magnitude: molybdenum, supported by the higher nickel floor, is responsible for 316’s higher density.

The practical lesson: if you ever encounter a stainless alloy with even higher molybdenum — 317 (3–4% Mo) or 317L, or the super-austenitic 254 SMO (6–6.5% Mo) and AL-6XN (6–7% Mo) — you can predict with confidence that density will be higher than 316, tracking the Mo content upward.

Density of 316 vs. 316L Stainless Steel: Are They the Same?

This is the question that comes up most often in our quoting process when a customer shifts between 316 and 316L on a revision.

Yes — 316 and 316L have identical density: 7,980 kg/m³.

Per ASTM A240/A240M-22, Table 1, the only compositional difference between 316 (S31600) and 316L (S31603) is the maximum carbon content:

• 316: Carbon ≤ 0.08%
• 316L: Carbon ≤ 0.030%

The chromium, nickel, and molybdenum ranges are identical. Carbon has an atomic mass of 12.011 — one of the lightest elements in the periodic table. At concentrations of 0.03–0.08%, reducing carbon from the 316 maximum to the 316L maximum changes the alloy density by approximately 3–4 kg/m³ — well within measurement noise for any practical calculation.

The reason to specify 316L over 316 is weld sensitisation, not weight. At carbon contents above approximately 0.035%, stainless steel held in the sensitisation temperature range (approximately 425–870°C) during welding precipitates chromium carbides at grain boundaries. This depletes chromium from the adjacent metal, reducing corrosion resistance in the heat-affected zone (HAZ). 316L’s lower carbon limit keeps chromium carbide precipitation below the threshold that causes sensitisation, preserving corrosion resistance in welded assemblies without requiring post-weld annealing.

If your part will be welded and will not receive solution-annealing heat treatment after welding, specify 316L. If your part will not be welded or will receive post-weld annealing, 316 and 316L are interchangeable for corrosion performance, and their densities are identical for every weight calculation.

Density of Stainless Steel 316 vs. 304: When the Difference Matters

The 50 kg/m³ density gap between 316 (7,980) and 304 (7,930) is 0.6%. This is a small number with specific practical thresholds.

Where the 304 vs. 316 density difference is negligible

Single-part weight estimates: A 300 × 200 × 2 mm bracket in 304 weighs 0.951 kg; in 316 it weighs 0.957 kg. The difference is 6 grams. For any calculation at the part level below about 50 kg, the 0.6% density difference is below the precision of any freight or handling decision.

Structural calculations: A column or beam design using 316 stainless steel instead of 304 will have a self-weight 0.6% higher. Within any structural safety factor, this is irrelevant.

Quoting and estimating: For job quoting, using 7,980 for 316 and 7,930 for 304 adds precision. Using 7,950 as a blended approximation for mixed 304/316 assemblies introduces ±0.3% error — acceptable in most quoting contexts.

Where the 304 vs. 316 density difference accumulates into a real number

Large assemblies with significant stainless content. A 316 stainless pharmaceutical vessel fabricated from an 8 mm plate, with a total surface area of 12 m², weighs:

• In 316: 12 × 0.008 × 7,980 = 765.1 kg
• In 304: 12 × 0.008 × 7,930 = 760.3 kg
• Difference: 4.8 kg — roughly 0.6% of the total, a meaningful lift for crane rigging calculations.

Freight pallets with many sheets. Twenty full sheets (1,220 × 2,440 mm) of 3 mm stainless:

• In 316: 20 × 1.220 × 2.440 × 3 × 7.98 = 1,427.5 kg
• In 304: 20 × 1.220 × 2.440 × 3 × 7.93 = 1,418.6 kg
• Difference: 8.9 kg — just under 10 kg on a pallet that may already be near a freight class boundary.

Long-run quoting. On a long-term supply contract for 316 stainless parts quoted at 304 density, the systematic underestimate of material weight produces systematic freight underestimates. Over hundreds of shipments, this is a real cost.

The rule I apply at ARCUSCNC: use the grade-specific density for any calculation where the total stainless content exceeds 100 kg. Below that threshold, the 0.6% error is within rounding tolerance for all practical purposes.

Density of Stainless Steel 316: Sheet Weight Table

Full sheet (1,220 × 2,440 mm) weights for 316 and 316L stainless steel. Formula: 1.220 × 2.440 × thickness (mm) × 7.98

The “vs. 304” column shows the per-sheet weight increment from the density upgrade. On a single 3 mm sheet, the difference is 0.4 kg. On a 20-sheet pallet, it is 8 kg.

316 Stainless Steel Density vs. Key Comparison Grades

This is the table most often needed when a grade substitution is under consideration.

The 317/317L observation deserves explanation. Type 317 contains 3–4% Mo and 11–15% Ni — both higher than 316’s 2–3% Mo and 10–14% Ni. By the molybdenum-density argument, 317 should be slightly denser than 316. The ASM Handbook lists both at 7,980 kg/m³ because the alloy density spread from composition variation within the A240 permitted range for each grade overlaps — 316 at the high end of its Ni/Mo range and 317 at the low end of its Ni/Mo range produce indistinguishable density values. For any fabrication calculation, 7,980 kg/m³ is correct for both 316 and 317.

The 254 SMO and AL-6XN note: These super-austenitic grades carry 6–7% Mo, two to three times 316’s addition. At that molybdenum level, density rises clearly above the 7,980 kg/m³ standard austenitic value to 8,000–8,060 kg/m³. For fabrication involving these high-alloy grades, use the grade-specific value.

International Grade Equivalents for 316 Stainless Steel — Density Is Always 7,980 kg/m³

316 stainless steel is sold under different designations in different markets. The density does not change across designation systems — 7,980 kg/m³ is 7,980 kg/m³ regardless of the standard body that certified the material.

Source: Michael Smith Engineers Limited, Material Grade Comparison Table.

When a European drawing specifies 1.4401, it means 316. When it specifies 1.4404, it means 316L. Both carry the same density: 7,980 kg/m³. I encounter 1.4404 regularly on drawings from German and Dutch machine builders — the material on the cutting table is the same 316L we process for domestic customers, and the weight calculation uses exactly the same number.

What the Density of Stainless Steel 316 Cannot Tell You

This section exists in our 304 article for the same reason it belongs here: density is one property, and for 316 in particular, the property that defines the grade is something else entirely.

Density does not quantify corrosion resistance. The entire reason to specify 316 over 304 — accepting the small density increase and the significant cost premium — is the molybdenum content. Molybdenum disrupts the electrochemical pit propagation mechanism in chloride environments, raising the pitting resistance equivalent (PRE = Cr + 3.3 × Mo + 16 × N) from approximately 18–20 for 304 to approximately 24–26 for 316. That PRE difference is the reason 316 is standard in marine deck hardware, food-processing equipment, pharmaceutical vessels, and coastal architectural applications. It is not visible in the density number.

Density does not confirm grade. The 50 kg/m³ difference between 304 and 316 is not detectable by weighing parts. A 304 part and a 316 part of identical geometry are indistinguishable in weight to any practical measurement. Grade confirmation requires chemical analysis — XRF (X-ray fluorescence) or OES (optical emission spectrometry) — to verify molybdenum presence. We run XRF verification on every incoming heat of stainless steel when the job requires food-grade or pressure vessel certification.

Density does not change with heat treatment. Solution-annealed 316L and cold-worked 316L have identical density. The work-hardening that increases yield strength from the A240 minimum of 205 MPa toward the cold-worked values has no measurable effect on the mass per unit volume. Use 7,980 kg/m³ for any 316 or 316L in any condition.

Frequently Asked Questions About Density of Stainless Steel 316

Q: What is the density of 316 stainless steel in kg/m³? 7,980 kg/m³. This is the value documented in ASM Handbook, Volume 1 for UNS S31600 and S31603 and consistent with ASTM A240/A240M-22 certified material. It applies equally to 316 and 316L — both grades have identical density.

Q: What is the density of 316 stainless steel in g/cm³? 7.98 g/cm³. Direct conversion of 7,980 kg/m³. This is the form most commonly cited in materials databases and laboratory references.

Q: What is the density of 316 stainless steel in lb/in³? 0.288 lb/in³ (precisely 0.2881 lb/in³). This is the value used in US fabrication estimating. Weight formula: Weight (lb) = Length (in) × Width (in) × Thickness (in) × 0.288.

Q: Is the density of 316 different from that of 316L? No. 316 (S31600) and 316L (S31603) have identical density: 7,980 kg/m³. The only difference is the maximum carbon content — 0.08% for 316, 0.030% for 316L. Carbon at these concentrations does not measurably affect density. The reason to choose 316L is weld sensitisation resistance; density plays no role in that decision.

Q: Why is 316 stainless steel denser than 304? Because 316 contains 2–3% molybdenum, which 304 does not. Molybdenum has a density of 10,280 kg/m³ — approximately 30% denser than iron. Dissolving 2–3% Mo into the iron-chromium-nickel matrix raises the alloy density by approximately 50 kg/m³ above 304’s value. The higher nickel floor in 316 (10–14% vs. 8–11% for 304) contributes a secondary upward pull.

Q: Can I use 304 density for weight calculations on 316 stainless parts? For individual parts, yes — the 0.6% error is within rounding tolerance for most applications. For large assemblies exceeding 100 kg of stainless content, for freight pallet weight declarations, or for lifting fixture design where weight budget is tight, use 7,980 kg/m³ specifically for 316. Systematically using 304 density for 316 parts underestimates weight by approximately 6 kg per tonne of material — a small but cumulative error in high-volume production.

References

1. ASM Handbook, Volume 1: Properties and Selection — Irons, Steels, and High-Performance Alloys, 10th Edition. ASM International, Materials Park, OH, 1990 (4th printing 1995). (Density of 316 and 316L stainless at 7,980 kg/m³; physical properties of austenitic stainless grades; molybdenum and nickel element density data used in the rule-of-mixtures analysis.)
2. ASTM A240/A240M-22, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications, ASTM International, 2022. (Table 1 chemical composition limits: 316/S31600 Cr 16–18%, Ni 10–14%, Mo 2–3%; 316L/S31603 identical except C ≤ 0.030%; basis for all composition data in this article.)
3. ASTM A480/A480M-22a, Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip, ASTM International, 2022. (General requirements governing A240 material; certification and testing requirements; surface quality standards relevant to laser-cut 316 stainless applications.)
4. Michael Smith Engineers Limited, Material Grade Comparison Table (DIN / BS / USA / Japan cross-reference). Available at michaelsmithengineers.co.uk. (Source for international grade equivalents: 1.4401 = 316, 1.4404 = 316L, SUS316, SUS316L, 316S16; note that this is a commercial reference document — exact compositions should be verified against applicable national standard for procurement.)

Density of Stainless Steel: All Grades, All Units, One Reference

• Author
• Recent Posts

Dr. Liu Che

Dr. Liu Che holds a Ph.D. in Engineering from Dalian University of Technology and completed postdoctoral research at the Mechanical Engineering Postdoctoral Fellowship of Harbin Institute of Technology. His research focuses on core algorithms for large-scale laser equipment integration, laser cladding remanufacturing, and real-time intelligent monitoring systems for processing. He possesses profound academic expertise in cutting-edge fields such as laser beam spatial shaping and the mechanism analysis of laser processing of special alloys. He has led numerous solutions to technical challenges in cutting and surface modification of high-hardness materials in the heavy machinery industry, demonstrating strong theoretical foundations and outstanding engineering implementation capabilities.

Latest posts by Dr. Liu Che (see all)

• Laser Coating Removal Without Damaging the Substrate - September 30, 2026
• Laser Cleaning for Paint Adhesion: Improving Surface Energy - September 29, 2026
• Common Mistakes in Laser Rust Removal Applications - September 23, 2026