304 vs 316 stainless steel: how to tell them apart
304 and 316 are the two stainless steels you are most likely to come across, and they look identical. The difference is a little molybdenum, which you cannot see, a magnet cannot find, and a scrap buyer will pay more for.
304 vs 316: key facts
| The two common grades | 304 (EN 1.4301) and 316 (EN 1.4401) |
|---|---|
| What separates them | 316 contains molybdenum. 304 does not |
| Why that matters | Molybdenum gives 316 much better resistance to salt water and acids |
| Magnet test | Both are austenitic and practically non magnetic, so a magnet cannot distinguish them |
| 400 series | Ferritic, little or no nickel, magnetic, and worth considerably less |
| UK steel packaging recycling rate | 85.5% in 2024 (final), 88.5% in 2025 (provisional) |
304 vs 316: what the grades actually are
Nominally, 304 runs at around 19% chromium and 10% nickel with no molybdenum. 316 runs at around 18% chromium, 14% nickel and between 2 and 3% molybdenum. The 400 series, of which 430 is the common one, sits at around 17% chromium with no nickel at all.
Those numbers are nominal rather than exact: the real composition ranges are set in BS EN 10088 and vary within tolerance. But the pattern is what drives the price. Nickel and molybdenum are both expensive alloying elements, and a yard is in effect buying the alloy content rather than the steel.
Why a magnet is not the answer
It is the test everyone reaches for, and on stainless it is close to useless. Austenitic grades such as 304 and 316 have magnetic permeability close to that of air, so neither sticks. Ferritic and martensitic grades, including most 400 series, do stick. So a magnet distinguishes families, badly.
It is worse than that. A 304 that was non magnetic as flat sheet can become slightly magnetic once it has been cold worked, which covers bending, pressing and machining. A formed sink bowl or a stamped bracket can read differently from the sheet it came from. Anyone concluding 'slightly magnetic, so it must be cheap 400 series' from a pressed component is likely to be wrong.
In practice a yard grading stainless properly uses a handheld analyser that reads the alloy content directly. If a buyer is grading your load by eye and magnet alone, that is worth noticing.
Where stainless comes from
Catering and food processing equipment, brewery and dairy tanks, balustrades and handrails, sinks and splashbacks, pipework and fittings, laboratory benching, marine fittings and architectural cladding. Kitchen refits and brewery decommissioning are two of the better sources of clean, consistent material.
Clean and consistent is the phrase that matters. A tank with its insulation, mild steel frame and copper fittings still attached is bought as the problem it is.
Getting the best out of a load
- Keep grades apart if you know them. Equipment nameplates and original paperwork often state the grade, and that is worth more than a guess.
- Separate the mild steel. Frames, brackets and fixings drag the whole load down.
- Strip insulation and non metallic attachments. Same reason.
- Ask for the analyser reading. A yard grading properly will not mind showing you.
Our stainless steel scrap price page carries the current UK figure, and the directory lists yards that buy stainless by postcode. For larger quantities, collection is usually a better route than driving it in, which is covered in our guide to scrap metal collection.
Telling 304 from 316 without an analyser
You usually cannot, and that is the honest answer. But three things narrow it down enough to be useful before you go.
- Look for the markings. Pipework, sheet and fittings are often stamped with the grade, either as 304 and 316 or as the European numbers 1.4301 and 1.4401. This is the only reliable method available to a seller.
- Check the paperwork. Equipment nameplates, original specifications and installation records frequently state the grade, and a tank from a brewery or dairy almost always has a documented specification somewhere.
- Think about the application. Marine fittings, coastal balustrades, swimming pool fixings and anything handling acids or salt are more likely to be 316, because that is what molybdenum is for. Indoor catering equipment and architectural trim are more likely 304.
None of that is proof, and a yard will read it with an analyser anyway. The value of knowing is that you can tell whether the grading you are offered is plausible.
What a ticket should show
Ask for a weighbridge ticket that states gross, tare and net weight, with the grade recorded against each separated parcel and the rate applied. For stainless specifically, ask what the analyser read. A yard grading properly has the reading on screen and no reason to withhold it.
If a mixed load is being bought as one grade, that grade will be the lowest one present. Separating 400 series from 300 series before weighing in, where the markings let you, is usually the single biggest improvement available to a seller.
Our stainless steel scrap price page carries the current UK figure, and The Waste Stock Calculator on the directory page converts a weight into a figure at today's pricing.
Frequently asked questions
What is the difference between 304 and 316 stainless steel?
316 contains between 2 and 3% molybdenum and usually more nickel; 304 contains no molybdenum. The molybdenum gives 316 much better resistance to salt water and acids, which is why it is used for marine and chemical work and why it is worth more as scrap.
Why is 316 stainless worth more than 304?
Because 316 contains between 2 and 3% molybdenum and typically more nickel than 304. Both are expensive alloying elements, and molybdenum is what gives 316 its resistance to salt water and acids.
Can I tell 304 from 316 with a magnet?
No. Both are austenitic and practically non magnetic. Yards use a handheld alloy analyser to read the composition directly.
Is stainless steel magnetic?
It depends on the grade. Austenitic grades such as 304 and 316 are practically non magnetic. Ferritic and martensitic grades, including most 400 series, are magnetic. A cold worked 304 can also become slightly magnetic.
Why is my stainless being paid at a low rate?
Usually because it is 400 series rather than 300 series, or because mild steel, insulation or other attachments are still on it. Ask which grade it has been bought as.
Where does most scrap stainless come from?
Catering and food processing equipment, brewery and dairy tanks, balustrades, sinks, pipework, laboratory benching and architectural cladding. Kitchen refits and brewery decommissioning are good sources.