The density of stainless steel 304 is 7,930 kg/m³. That is the value cited in the ASM Handbook, Volume 1 and consistent with every compliant material test report (MTR) I have seen for UNS S30400 sheet and plate in 17 years of production. It is not an approximation.
The practical challenge is that this number appears in different forms depending on where you look it up — 7.93 g/cm³ in a materials database, 0.286 lb/in³ in a fabrication estimate, 494 lb/ft³ in a structural table. They are all the same value. This article provides the complete conversion set, the official source chain that establishes the origin of 7,930 kg/m³, and ready-to-use weight tables that make the density value immediately applicable to sheet metal calculations.
The Official Value for Density of Stainless Steel 304 — Source and Authority
Before using any density value in an engineering calculation, it is important to know its source. For stainless steel 304, the path is:
ASTM A240/A240M-22 is the procurement specification for 304 stainless steel flat products (plate, sheet, and strip). It sets the chemical composition limits (Table 1) and mechanical property minimums (Table 2) that mill-supplied 304 must meet. The chemical limits for 304 (UNS S30400) are: Chromium 18.0–20.0%, Nickel 8.0–11.0%, Carbon ≤ 0.08%, Manganese ≤ 2.00%, Silicon ≤ 0.75%. The specification does not directly list density — that is, not a certifiable property under A240 — but the composition range it defines is the basis from which density is derived.
ASM Handbook, Volume 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (10th Edition, ASM International, 1990) is the metallurgical reference that documents physical properties — including density — for stainless grades consistent with ASTM A240 chemistry. The value cited is 7,930 kg/m³ for austenitic 304 in the annealed condition. This is the authoritative engineering reference value for the grade.
The range of values you see across different sources — 7,900, 7,930, 7,940, and occasionally 8,000 kg/m³ — all arise from the same source: nickel content within the A240-permitted range of 8.0–11.0% by weight. Nickel has a density of 8,908 kg/m³, significantly above iron’s 7,874 kg/m³. A heat of 304 at the low end of the nickel range (8.0% Ni) is measurably less dense than a heat at the high end (11.0% Ni). Both are fully compliant with ASTM A240. The difference in bulk density between these extremes is approximately 50–80 kg/m³.
7,930 kg/m³ is the correct central value for any weight or density calculation involving 304 stainless steel. It represents the mid-range nickel composition and is the value used in our quoting system, our freight calculations, and our lifting fixture specifications.
Density of Stainless Steel 304 in Every Unit System
This is the complete conversion table. The source value is 7,930 kg/m³; all other values are exact conversions.
For data source, please refer to the Metal Density Chart.
Primary engineering units
| Unit System | Symbol | Value | Application |
|---|---|---|---|
| Kilograms per cubic metre | kg/m³ | 7,930 | SI standard; structural engineering; most international specifications |
| Grams per cubic centimetre | g/cm³ | 7.930 | Materials databases; scientific references; lab measurements |
| Grams per millilitre | g/mL | 7.930 | Identical to g/cm³; used in chemistry and pycnometry |
| Kilograms per decimetre cubed | kg/dm³ | 7.930 | Identical to g/cm³; used in European engineering |
| Tonnes per cubic metre | t/m³ | 7.930 | Structural and civil engineering; identical to g/cm³ numerically |
| Megagrams per cubic metre | Mg/m³ | 7.930 | Materials science; identical to g/cm³ numerically |
US customary and imperial units
| Unit System | Symbol | Value | Application |
|---|---|---|---|
| Pounds per cubic inch | lb/in³ | 0.2863 | US fabrication estimating; machine shop weight calculations |
| Pounds per cubic foot | lb/ft³ | 494.9 | Structural engineering; building and construction |
| Ounces per cubic inch | oz/in³ | 4.581 | Rarely used; occasionally appears in older US references |
| Short tons per cubic yard | st/yd³ | 6.694 | Civil and mining engineering |
The 0.286 vs. 0.2863 lb/in³ question
Most US fabrication references round to 0.286 lb/in³. The exact conversion of 7,930 kg/m³ is:
7,930 kg/m³ × (1 lb / 0.453592 kg) × (1 m / 39.3701 in)³ = 0.28634 lb/in³
Rounded to three decimal places: 0.286 lb/in³.
The rounding introduces an error of 0.12%. On a 100 lb part, that is 0.12 lb — less than 2 oz. For freight and weight estimation, 0.286 is the correct working value. For high-precision engineering calculations where the unrounded value matters, use 0.2863 lb/in³.
Surface density — the value sheet metal workers actually use
In sheet metal fabrication, weight is almost always calculated per unit area rather than per unit volume. The surface density (weight per unit area per unit thickness) of 304 stainless steel is:
7.93 kg/m² per millimetre of thickness
Or equivalently: a 1 mm thick sheet of 304 stainless steel weighs 7.93 kg per square metre of area.
This is the starting point for every sheet weight calculation:
Sheet weight (kg) = Length (m) × Width (m) × Thickness (mm) × 7.93
Density of Stainless Steel 304: Weight Calculation Formulas
Formula 1 — SI units (metric)
Weight (kg) = L (m) × W (m) × T (m) × 7,930
Or equivalently, using thickness in millimetres:
Weight (kg) = L (m) × W (m) × T (mm) × 7.93
Example: A 600 mm × 400 mm × 2 mm 304 stainless blank: Weight = 0.600 × 0.400 × 2 × 7.93 = 3.81 kg
Formula 2 — Imperial units
Weight (lb) = L (in) × W (in) × T (in) × 0.286
Example: A 24″ × 16″ × 0.079″ (2 mm) 304 stainless blank: Weight = 24 × 16 × 0.079 × 0.286 = 8.66 lb
Formula 3 — Mixed units (mm dimensions, kg result)
Weight (kg) = L (mm) × W (mm) × T (mm) × 7.93 × 10⁻⁶
Example: Same 600 × 400 × 2 mm blank in all-millimetre inputs: Weight = 600 × 400 × 2 × 7.93 × 10⁻⁶ = 3.81 kg ✓
304 Stainless Steel Sheet Weight Table — Standard Metric Sizes
This table gives full-sheet weights for standard 304 stainless sheet gauges and plate thicknesses on a 1,220 × 2,440 mm (4′ × 8′) sheet — the most common format in stock at service centres globally.
Formula: 1.220 × 2.440 × thickness (mm) × 7.93
| Thickness | Gauge equiv. | Weight per m² (kg) | Full sheet weight (1,220 × 2,440 mm) |
|---|---|---|---|
| 0.5 mm | 25 ga | 3.97 | 11.8 kg |
| 0.8 mm | 22 ga | 6.34 | 18.9 kg |
| 1.0 mm | 20 ga | 7.93 | 23.6 kg |
| 1.2 mm | 18 ga | 9.52 | 28.4 kg |
| 1.5 mm | 16 ga | 11.90 | 35.5 kg |
| 2.0 mm | 14 ga | 15.86 | 47.3 kg |
| 2.5 mm | 12 ga | 19.83 | 59.1 kg |
| 3.0 mm | 11 ga | 23.79 | 70.9 kg |
| 4.0 mm | — | 31.72 | 94.6 kg |
| 5.0 mm | — | 39.65 | 118.2 kg |
| 6.0 mm | — | 47.58 | 141.8 kg |
| 8.0 mm | — | 63.44 | 189.1 kg |
| 10.0 mm | — | 79.30 | 236.4 kg |
| 12.0 mm | — | 95.16 | 283.7 kg |
| 16.0 mm | — | 126.88 | 378.2 kg |
| 20.0 mm | — | 158.60 | 472.8 kg |
| 25.0 mm | — | 198.25 | 591.0 kg |
304 Stainless Steel Sheet Weight Table — Standard Imperial Sizes
Standard 4′ × 8′ sheet (48″ × 96″). Formula: 48 × 96 × thickness (in) × 0.286
| Gauge | Nominal thickness (in) | Decimal thickness | Full sheet weight (4′ × 8′) |
|---|---|---|---|
| 26 ga | — | 0.0187″ | 24.6 lb |
| 24 ga | — | 0.0239″ | 31.5 lb |
| 22 ga | — | 0.0299″ | 39.4 lb |
| 20 ga | 1/32″ | 0.0359″ | 47.3 lb |
| 18 ga | 3/64″ | 0.0478″ | 63.0 lb |
| 16 ga | 1/16″ | 0.0598″ | 78.8 lb |
| 14 ga | 5/64″ | 0.0747″ | 98.4 lb |
| 12 ga | 7/64″ | 0.1046″ | 137.8 lb |
| 11 ga | 1/8″ | 0.1196″ | 157.6 lb |
| 3/16″ plate | — | 0.1875″ | 247.1 lb |
| 1/4″ plate | — | 0.2500″ | 329.5 lb |
| 3/8″ plate | — | 0.3750″ | 494.2 lb |
| 1/2″ plate | — | 0.5000″ | 659.0 lb |
| 3/4″ plate | — | 0.7500″ | 988.5 lb |
| 1″ plate | — | 1.0000″ | 1,317.9 lb |
Note: US stainless steel gauge thicknesses differ from carbon steel gauges. The values above follow the standard stainless steel sheet gauge system.
How Density of Stainless Steel 304 Applies to Specific Fabrication Calculations
Laser-cut blank weight for quoting
In our quoting process, every laser-cut 304 stainless job starts with a sheet weight calculation. Before programming the nest, I know the total sheet stock required for the job. After nesting is complete, the software reports the part area and the drop/skeleton area. I apply the density separately to each:
Assist Gas Selection: nitrogen assist gas for stainless steel
- Parts weight = part area (m²) × thickness (mm) × 7.93
- Scrap weight = scrap area (m²) × thickness (mm) × 7.93
- Total sheet weight = full sheet area × thickness × 7.93 (always 1.220 × 2.440 × T × 7.93)
The three numbers must reconcile: parts + scrap = total sheet. If they don’t, there’s an error in the nest area calculation.
For a recent job: 3 mm 304 sheet, 74% utilization. Full sheet weight = 1.220 × 2.440 × 3 × 7.93 = 70.9 kg. Parts = 70.9 × 0.74 = 52.5 kg delivered. Scrap = 70.9 × 0.26 = 18.4 kg recovered.
Freight weight for pallets of cut parts
The freight carrier needs the total pallet weight, which is parts weight plus pallet weight plus any dunnage. Underestimating parts weight means the pallet is declared at a lower weight class than actual, which triggers freight adjustments, delayed delivery, and in some jurisdictions, compliance issues under transport regulations.
For a pallet of 3 mm 304 stainless parts at 72% sheet utilisation, 10 full sheets:
- Total parts weight = 10 × 70.9 × 0.72 = 510 kg
- Add pallet (typically 20–25 kg for a wooden pallet) and strapping
Arriving at 535 kg before the carrier picks up is the number. Getting it wrong by 5% because an incorrect density was used means the pallet is actually 562 kg — 27 kg above what was declared.
Lifting and handling fixture design
Vacuum pad systems for 304 stainless sheet handling are specified by maximum sheet weight. A vacuum pad system rated to 80 kg per pad, with 4 pads, handles up to 320 kg per sheet. For a 10 mm thick 304 stainless full sheet: 1.220 × 2.440 × 10 × 7.93 = 236 kg. That is within the 320 kg limit with a margin. For a 16 mm plate: 378 kg — over the 4-pad limit, requiring either a 6-pad configuration or a different handling method.
These calculations depend directly on density accuracy. Using the wrong density — even one that is 1–2% off — can push a plate weight across an equipment capacity boundary.
Density of Stainless Steel 304 Compared to the Grades Most Commonly Substituted for It
These are the comparisons that come up in specification decisions at our facility.
| Grade | Density (kg/m³) | lb/in³ | Difference from 304 | Why it’s considered as an alternative |
|---|---|---|---|---|
| 304 / 304L (S30400/S30403) | 7,930 | 0.286 | — | Reference |
| 316 / 316L (S31600/S31603) | 7,980 | 0.288 | +50 kg/m³ (+0.6%) | Chloride resistance upgrade |
| 303 (S30300) | 7,930 | 0.286 | 0 | Free-machining version of 304; not weldable |
| 301 (S30100) | 7,880 | 0.285 | −50 kg/m³ (−0.6%) | Work-hardenable; springs, clips |
| 321 (S32100) | 7,920 | 0.286 | −10 kg/m³ (−0.1%) | Titanium-stabilised; high-temperature service |
| 2205 duplex (S32205) | 7,805 | 0.282 | −125 kg/m³ (−1.6%) | Strength upgrade + corrosion resistance |
| 430 ferritic (S43000) | 7,720 | 0.279 | −210 kg/m³ (−2.6%) | Cost reduction; non-magnetic; no nickel |
For every grade in this table except 430, the density difference from 304 is less than 1.6%. In a weight calculation, none of these differences changes the answer enough to affect a freight classification or lift equipment decision. The reasons to specify one over another are always corrosion, mechanical, or process requirements, not density.
The one meaningful density step is 304 to 430 ferritic: −210 kg/m³, or 2.6% lighter. On a large panelling job — cladding, decorative trim, food equipment panels — where 430 is technically acceptable, the weight saving is real and worth factoring into a total assembly weight.
Data source: density of stainless steel all grades
Learn more:
Engineer’s Guide: Is Stainless Steel Magnetic? Explaining Different Grades
Frequently Asked Questions About the Density of Stainless Steel 304
Q: What is the density of stainless steel 304 in kg/m³?
7,930 kg/m³. This is the value documented in the ASM Handbook, Volume 1, for annealed 304 (UNS S30400) and is consistent with ASTM A240/A240M-22 certified material. It applies equally to 304, 304L, and 304H — the density is the same across all three variants.
Q: What is the density of stainless steel 304 in g/cm³?
7.93 g/cm³. This is a direct unit conversion of 7,930 kg/m³ (multiply by 0.001). It is the form most commonly cited in materials databases and scientific references.
Q: What is the density of stainless steel 304 in lb/in³?
0.286 lb/in³ (precisely: 0.2863 lb/in³). This is the value used in US customary fabrication estimating and imperial weight calculations. The formula for sheet weight in imperial units is: Weight (lb) = Length (in) × Width (in) × Thickness (in) × 0.286.
Q: Is the density of 304 stainless steel the same as 304L?
Yes. 304L differs from 304 only in carbon content — 0.030% maximum vs. 0.08% maximum per ASTM A240 Table 1. Carbon at these concentrations has no measurable effect on density. Both grades are 7,930 kg/m³.
Q: What is the weight of a 4′ × 8′ sheet of 304 stainless steel in 12 gauge?
12-gauge stainless steel is 0.1046″ thick. Weight = 48 × 96 × 0.1046 × 0.286 = 137.8 lb (62.5 kg). This is for a standard 48″ × 96″ (4′ × 8′) sheet.
Q: Why does my supplier’s datasheet say 7.9 g/cm³ instead of 7.93 g/cm³ for 304?
7.9 g/cm³ is a rounded value — it truncates 7.93 to one decimal place. It introduces an error of approximately 0.38%. For most applications, this is acceptable. For precise weight calculations on large volumes of material, use the full 7.93 g/cm³ (7,930 kg/m³) value.
References
- 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 requirements for 304/S30400, 304L/S30403, and 304H/S30409; the composition limits from which density variation across the 304 family is derived.)
- ASM Handbook, Volume 1: Properties and Selection — Irons, Steels, and High-Performance Alloys, 10th Edition. ASM International, Materials Park, OH, 1990 (4th printing 1995). (Physical properties of austenitic stainless grades; 7,930 kg/m³ as the documented density value for 304 stainless steel; wrought stainless steel properties by grade family.)
- 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 framework for A240 material; surface finish definitions; dimensional tolerances that affect sheet weight in practice.)
- NIST Special Publication 330 (2019 Edition), The International System of Units (SI), National Institute of Standards and Technology. (Basis for all SI unit conversions and the definition of kg/m³ as the SI unit of density; source for exact conversion factors between SI and US customary units used in the conversion table.)
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