304 vs 316 Stainless Steel Plate: Density & Weight Differences

Stainless 316 is denser than stainless 304, but only just. Grade-specific reference values put 304 at 7.93 g/cm³ and 316 at 7.98 g/cm³, a difference of 0.63%. An identical plate in 316 therefore weighs 0.63% more than the same plate in 304, whatever its size and whatever its shape.

On a 10 × 1500 × 3000 mm plate that is 2.25 kg on 356.85 kg. It is a real difference and it is almost never the reason to choose between the two grades.

The density figures

These are the values the Steel Plate Weight Calculator applies, and they are the grade-specific figures rather than rounded standard values. The distinction matters, and the next section covers it.

The L variants, 304L and 316L, are low-carbon versions of the same alloys. The carbon reduction is a fraction of a percent by mass and has no practical effect on density, so 304 and 304L share a figure, as do 316 and 316L.

Why published densities for these grades disagree

You will find 304 quoted as 7.90, 7.93 and 8.00 g/cm³ on different pages, and 316 as 7.98 or 8.00. That looks like disagreement and mostly is not.

The British Stainless Steel Association tabulates physical properties to BS EN 10088-1 rounded to the nearest 100 kg/m³, which gives 7,900 kg/m³ for 304 and 8,000 kg/m³ for 316. Grade-specific data sources give 7,930 and 7,980. Both are defensible; one is rounded to a standard step and the other is not.

The rounding changes the answer to the question this article is about:

The rounded values double the apparent gap, because rounding pushed 304 down and 316 up. Neither set is wrong, but they are not interchangeable, and quoting a difference without saying which basis produced it is how two correct sources end up contradicting each other.

Pick one basis, note which one, and hold it across a job. Mixing them inside a single estimate is the only genuinely wrong option.

Both are nominal engineering densities: agreed reference values for calculation. Neither is a measured property of a particular heat of steel or of the plate in front of you.

Same geometry, one multiplier

Because geometry is identical, the entire weight difference between the two grades is the ratio of their densities:

7.98 ÷ 7.93 = 1.0063

That factor applies to every shape and every thickness. A 316 plate, a 316 disc, a 316 ring and a 316 gusset each weigh 1.0063 times their 304 equivalent. Nothing about the shape changes it.

In practical terms:

304: kg/m2 = thickness in mm × 7.93
316: kg/m2 = thickness in mm × 7.98

Worked example: the same plate in both grades

Known values: 10 mm × 1500 mm × 3000 mm. Area 4.50 m².

In 304:

V = 0.010 × 1.500 × 3.000 = 0.045000 m3
m = 0.045000 × 7,930 = 356.85 kg (786.7 lb)

In 316:

m = 0.045000 × 7,980 = 359.10 kg (791.7 lb)

Result: 2.25 kg, 0.63% more. Interpretation: less than the weight of a hand tool, on a plate that takes a crane to move. Reverse check: 356.85 × 1.0063 = 359.10, and the carbon steel equivalent at 7,850 kg/m³ is 353.25 kg, which makes 304 itself 1.02% heavier than mild steel.

Worked example: across three plate sizes

Known values: three common metric plate sizes, both grades.

Interpretation: the percentage is fixed at 0.63% and the kilograms scale with the plate. That is the whole relationship. Reverse check: 0.30 ÷ 47.58 = 0.0063, and the same ratio holds on both larger sizes.

Reference: weight per unit area in both grades

For quick checks, the mass per square metre of each grade at common plate thicknesses. Multiply by the plate area to get the weight.

In imperial, 304 works out at about 495.0 lb/ft³ and 316 at about 498.1 lb/ft³, against 490 lb/ft³ for carbon steel:

Worked example: a 4 × 8 sheet in both grades

Known values: 1/2 in × 48 in × 96 in, 32 ft².

304: 20.62 × 32 = 660.0 lb (299.4 kg)
316: 20.75 × 32 = 664.2 lb (301.3 kg)

Result: 4.2 lb (1.9 kg) apart. Interpretation: on a plate a crane has to move, the grade difference is roughly the weight of a pair of boots. Reverse check: 660.0 × 1.0063 = 664.2.

Worked example: where the difference does start to matter

Known values: a 20 tonne order of 304 plate, re-specified in 316 at the same dimensions.

grade-specific basis: 20 × (7.98 ÷ 7.93) = 20.126 t, +126 kg
EN 10088-1 rounded:   20 × (8.00 ÷ 7.90) = 20.253 t, +253 kg

Result: between 126 kg and 253 kg depending on the density basis. Interpretation: at tonnage this size the difference is worth calculating, and it is worth being clear about which density basis the quotation used, because the two answers differ by a factor of two. Reverse check: 126 ÷ 20,000 = 0.63%, 253 ÷ 20,000 = 1.27%.

This is the situation where the rounding question stops being academic. On one plate it is noise. On a shipload it is a line item, and the two parties should be using the same number.

Why 316 is denser

Briefly, because the detail is not where the value is.

Both grades are austenitic stainless steels, with a face-centred cubic structure and a chromium-nickel base. The difference is that 316 carries molybdenum, typically around 2%, along with a slightly higher nickel content, and 304 carries neither.

Molybdenum is a heavy element, roughly 96 in atomic mass against about 56 for iron. Substituting a couple of percent of iron for molybdenum raises the average atomic mass of the alloy slightly, and density follows. The nickel difference works the same way to a smaller degree.

That is the mechanism, and its size is the 0.63% above. It is not enough to be a selection criterion on its own.

What the grade choice is actually about

The reason 316 exists is corrosion resistance, not weight. The molybdenum that makes it marginally denser also makes it substantially more resistant to pitting and crevice corrosion in chloride environments: marine atmospheres, de-icing salt, some process chemistry, some food and pharmaceutical duties.

That is the decision. The weight difference is a consequence of it, worth calculating for transport and lifting purposes and never worth driving it.

Two other differences follow the same pattern. 316 normally costs more per kilogram than 304, because molybdenum and the higher nickel content both carry an alloy surcharge that mills republish regularly as those markets move. And both grades work-harden, conduct heat differently from carbon steel during welding, and need their own consumables and procedures.

None of that is visible in a density figure. Suitability for a corrosive service, like suitability for a structural one, is an engineering assessment against the actual conditions, not something a weight calculator can answer.

Against carbon steel and against the rest of the family

Set beside mild steel at 7.85 g/cm³, both austenitic grades are heavier: 304 by 1.02% and 316 by 1.66%. Those are small numbers, and smaller than most people expect.

They are also not representative of stainless steel as a whole. Ferritic and martensitic grades such as 430 and 410 sit around 7.70 and 7.74 g/cm³, which makes them lighter than mild steel, not heavier. The blanket statement that stainless weighs more than carbon steel is true for the austenitic grades in this article and false for a whole family of others. Mild steel against stainless steel works through the full range.

Getting the number right in practice

Use grade-specific densities where you have them, and say which source. 7.93 and 7.98 are the values this site uses throughout.

Do not carry more precision than the source supports. These are reference figures good to roughly the second decimal place. Running 7.9312 through a calculation makes an estimate look like a measurement.

Compare the density difference against the tolerance. Plate is rolled to a thickness tolerance, and on ordinary plate that tolerance moves the delivered weight by several percent. A 0.63% grade difference sits well inside it. Theoretical versus actual steel plate weight covers the size of the effect.

Note that EN 10029 does not cover stainless plate. Its 2010 edition excludes stainless steels explicitly, so the class A to D thickness tolerances described in the EN 10029 guide are not the ones governing your 304 or 316 plate. Confirm which dimensional standard applies with the supplier.

304 vs 316 stainless FAQs

Is 316 stainless heavier than 304? Yes, by about 0.63% using grade-specific densities of 7.93 and 7.98 g/cm³. Using EN 10088-1 values rounded to the nearest 100 kg/m³, 7.90 and 8.00, the difference reads as 1.27%.

What is the density of 316 stainless steel? 7.98 g/cm³, which is 7,980 kg/m³ or 0.2883 lb/in³, as a grade-specific reference value. Rounded to the nearest 100 kg/m³ per EN 10088-1 it is quoted as 8,000 kg/m³.

Does 316L weigh the same as 316? For practical purposes yes. The L denotes a lower carbon content, a change of a fraction of a percent by mass, with no meaningful effect on density. The same applies to 304 and 304L.

Why is 316 denser than 304? Because 316 contains around 2% molybdenum and slightly more nickel. Molybdenum has a higher atomic mass than the iron it replaces, which raises the alloy’s average density slightly.

Should the weight difference affect which grade I choose? No. At under 1% it is smaller than ordinary plate thickness tolerance. The grade decision is about corrosion resistance in the actual service conditions, and it belongs with whoever is responsible for material selection.

A small number, stated precisely

The honest answer to “how much heavier is 316 than 304” is 0.63% on grade-specific densities, or 1.27% if you are working from EN 10088-1 values rounded to the nearest 100 kg/m³. Both answers are defensible and they differ by a factor of two, so the basis has to travel with the number.

Beyond that, the arithmetic is simple: work out the geometry once, then multiply by 7.93 or 7.98 kilograms per square metre per millimetre of thickness. Put your plate into the Steel Plate Weight Calculator and change nothing but the grade to see the whole effect in one figure.

Density values used here are the grade-specific figures carried in this site’s material data. The rounded alternatives are those published by the British Stainless Steel Association from BS EN 10088-1, which tabulates stainless densities to the nearest 100 kg/m³.