304 Stainless Steel Density in kg/m³
Use 7,900 kg/m³ (7.90 g/cm³) as a sourced starting point for a room-temperature 304 stainless steel weight estimate. Some supplier data sheets use 8,000 kg/m³. Follow the value required by your supplier or project, and record it with the dimensions. The calculator below compares density choices without treating them as a guaranteed tolerance.
Sheet-metal pieces with cutouts: removed areas reduce the net metal volume. Representative photo: Jmettlen / Wikimedia Commons, CC BY-SA 3.0. Cropped and darkened for this layout.
What do 304 density data sheets actually say?
The references below describe material properties. Their spread is a comparison of published values, not a measured batch range or a permissible density tolerance.
| Reference | Published density | In kg/m³ | What the number means |
|---|---|---|---|
| ATI Type 304 | 7.90 g/cm³ | 7,900 | ATI lists this physical property for its Type 304 product forms. Its inch-pound table uses the rounded value 0.285 lb/in³. |
| Outokumpu Core 304/4301 | 7.9 kg/dm³ | 7,900 | The Core range physical-properties table also gives 7.9 kg/dm³ for Core 304L/4307. |
| thyssenkrupp Materials UK, 304/1.4301 | 8,000 kg/m³ | 8,000 | A different supplier's published reference. Its data sheet describes typical properties, not a warranty of each delivered product. |
On a small screen, scroll the table horizontally to see every column.
Use one documented reference consistently. Do not average several suppliers’ values and label the result “certified” or “exact.”
Which density should you use in a weight calculation?
Density is mass divided by material volume: ρ = m / V. The symbol ρ means density. One cubic metre of solid 304 at a density of 7,900 kg/m³ has a mass of 7,900 kg; one litre has a mass of 7.90 kg. A hollow part contains less metal than a solid part with the same outside dimensions.
Choose the density specified for the job. If none is specified, the calculator starts at 7,900 kg/m³ because that value can be traced to the ATI and Outokumpu references above. A different documented value may be appropriate for your material.
The calculator retains 7,930 kg/m³ as an alternative estimating assumption. It is not the mathematical midpoint of 7,900 and 8,000; that midpoint is 7,950. Extra digits alone do not make an estimate more accurate.
At unchanged volume, switching from 7,900 to 8,000 increases calculated mass by 100 ÷ 7,900 × 100% = 1.27%. Whether that matters depends on the required mass accuracy and the uncertainty in the dimensions.
Type 304 is an austenitic stainless steel with specified composition limits. This representative micrograph shows its grain structure; it does not measure density or verify the grade of your stock.
Unsensitized Type 304 microstructure. Image: Webcorr / Wikimedia Commons, CC BY-SA 3.0.
304 density in g/cm³, kg/L and lb/in³
These are conversions of the selected metric value. Additional decimal places describe the conversion, not the certainty of the material property.
| Density basis | g/cm³ | kg/L | lb/in³ | lb/ft³ |
|---|---|---|---|---|
| 7,900 kg/m³ | 7.90 | 7.90 | 0.2854 | 493.2 |
| 7,930 kg/m³ | 7.93 | 7.93 | 0.2865 | 495.1 |
| 8,000 kg/m³ | 8.00 | 8.00 | 0.2890 | 499.4 |
On a small screen, scroll the table horizontally to see every column.
To convert g/cm³ to kg/m³, multiply by 1,000. To convert kg/m³ to lb/in³, divide by approximately 27,679.90. NIST conversion factors support these unit changes.
Why 0.285 lb/in³ does not convert back to exactly 7,900
ATI publishes 0.285 lb/in³ and 7.90 g/cm³ as rounded reference values. Converting 7,900 kg/m³ more closely gives 0.2854056 lb/in³, which rounds to 0.285 at three decimal places. Reversing an already rounded number loses precision; it does not establish a different material density.
How to calculate plate, bar and tube mass
Mass equals material volume × density × quantity. The examples use 7,900 kg/m³ and one item. In workshop language this is often called “weight”; the kg and lb results here are units of mass.
Plate or sheet
Use length L, width W and thickness T in metres. For dimensions all in millimetres: mass in kg = L × W × T × density ÷ 1,000,000,000.
2,000 × 1,000 × 10 mm: 0.020 m³ × 7,900 = 158.00 kg. Mass per area is 79.00 kg/m².
Solid round bar
Use diameter and length in metres. The circular cross-sectional area is multiplied by length.
50 mm diameter × 6 m: 0.011781 m³ × 7,900 ≈ 93.07 kg, or 15.51 kg/m.
Round pipe or tube
Use actual outside diameter (OD), not nominal pipe size. Inside diameter (ID) = OD − 2 × wall thickness. Put all lengths in metres and require ID greater than zero.
60.3 mm OD × 3.91 mm wall × 6 m: ID = 52.48 mm; mass ≈ 32.83 kg, or 5.47 kg/m.
These idealized shapes have uniform dimensions and no cutouts. For CAD parts, use the net solid-material volume; for tubes, exclude the empty bore. Use a separate calculation for contents, fittings or an irregular section.
304 stainless steel weight calculator
Select the shape and enter its dimensions. Length is in millimetres for plate, but metres for bar and tube. Load the shape example to reproduce the formulas above. All results stay in your browser.
All dimensions and density must be positive. Quantity must be a whole number from 1 to 1,000,000. Custom density is your supplied assumption; this calculator does not establish grade identity.
Enter dimensions to calculate nominal mass.
Edit dimensions ↑
How much can a thickness difference change the weight?
A nominal size describes the ordered geometry. It does not prove the exact dimensions of every delivered part. Changing thickness changes metal volume and mass even when the material density stays the same.
At 7,900 kg/m³, a uniform 10.00 mm thickness gives 158.00 kg. If the uniform measured thickness were 9.80 mm, the same calculation would give 154.84 kg: 3.16 kg, or 2.0%, less. This is an assumed dimensional example, not a permitted tolerance.
For a tube, wall thickness changes the metal area along its whole length. Do not treat a pipe's nominal size as its outside diameter. If the section is irregular, use net CAD volume or measured geometry instead of the simple round-tube formula.
- Record the density source, dimensions, units and quantity with the estimate.
- Subtract known holes and cutouts; add fittings, contents, packaging and pallets separately.
- Use the contractual basis for invoicing: theoretical mass and scale mass are different methods.
- For a load or freight decision, verify actual total mass and account for measurement uncertainty.
For dimensional acceptance of flat products, use the applicable specification and product form. The ASTM A240 vs A480 guide explains that separate question.
Does temperature change 304 stainless steel density?
Yes. When a freely expanding piece of solid 304 is heated, its volume increases. If it gains or loses no material, its mass stays constant, so its density falls. The part does not lose mass simply because it expands.
For hot-process calculations, use density data at the relevant temperature or a consistent thermal-expansion model. Do not combine hot dimensions with a room-temperature density and expect an exact mass. The Outokumpu Core data sheet gives thermal-expansion information for its grades.
Composition, material condition and reporting precision also affect the reference basis. Differences between the suppliers’ tables do not, by themselves, reveal which effect caused the difference. Nominal thickness variation is a geometry issue; it does not change the intrinsic density of the metal.
How does 304 compare with 304L, 316 and 430?
Use the same volume when comparing mass. These source-specific values are useful calculation references, but their overlap makes density unsuitable for identifying a grade.
| Grade reference | Density, kg/m³ | Mass of 0.020 m³ | Source |
|---|---|---|---|
| 304 / 1.4301 | 7,900 | 158.0 kg | Outokumpu Core 304/4301 |
| 304L / 1.4307 | 7,900 | 158.0 kg | Outokumpu Core 304L/4307 |
| 316 / 1.4401 | 8,000 | 160.0 kg | Outokumpu Supra 316/4401 |
| 430 / 1.4016 | 7,700 at 20°C | 154.0 kg | thyssenkrupp Materials UK 430 |
On a small screen, scroll the table horizontally to see every column.
On this selected basis, 316 calculates 2.0 kg heavier than 304 for the example volume. Using thyssenkrupp's 8,000 kg/m³ reference for 304 would give the same calculated mass as 316. This illustrates why density cannot settle a grade-identification question.
The low-carbon 304L designation concerns composition and related service behavior; it is not a useful weight-saving choice. Use material records and appropriate composition testing for identification. See the 304 vs 316 identification guide when the grade itself is uncertain.
Questions about using a density estimate
Can I obtain an accurate density by weighing a sample?
You also need an accurate material volume. For a regular, clean sample, divide measured mass by measured volume and record the temperature and measurement method. Errors in thickness, diameter or displaced-volume measurement carry into the result. A casual check is not a substitute for traceable material identification.
Does polishing or a surface coating change the calculation?
Polishing can remove metal, so calculate from the final dimensions when that loss matters. For a coated or laminated part, calculate each material's volume and density separately, then add the masses. Applying 304 density to the entire combined volume can misstate the total.
What does “specific gravity 7.9” mean?
Specific gravity, also called relative density, is a ratio to a stated reference density, usually water for a solid. It has no unit. It is close numerically to density in g/cm³ when the reference water density is close to 1 g/cm³, but the reference temperatures matter. Keep a supplier's density units and test basis intact.
Related material and fabrication guides
Density and unit-conversion references
- ATI Type 304 — density and composition for Type 304 product forms.
- Outokumpu Core range data sheet — 304/304L physical properties, including density and thermal expansion.
- thyssenkrupp Materials UK, 304/1.4301 — alternative supplier density reference and typical-property scope.
- Outokumpu Supra range data sheet — 316/1.4401 comparison value.
- thyssenkrupp Materials UK, 430/1.4016 — density at 20°C.
- NIST Guide to the SI, Chapter 8 — mass-density definition and notation.
- NIST Guide to the SI, Appendix B.9 — mass and density conversion factors.
Planning a 304 stainless steel laser welding application?
Share the material grade, thickness, joint drawing, production target and required finish. Oceanplayer Laser can help define a laser-welding configuration and a representative sample-test plan.