304 and 316 are the two most widely used stainless steels, and they look identical. The difference is one ingredient: 316 contains 2–3% molybdenum, which makes it far better at resisting salt, chlorides and many chemicals. 316 also typically costs about 20–40% more. This guide compares them side by side and tells you when the extra cost is worth it.
The short answer
- Choose 304 for kitchens, indoor use, inland outdoor use, food equipment and general fabrication. It’s the better value.
- Choose 316 within a few miles of the sea, around pools and spas, near road de-icing salt, for boats, and in chemical, medical and pharmaceutical settings.
- Strength, appearance, weldability and food safety are essentially the same.
- You can’t tell them apart by eye or with a magnet. You need a molybdenum test or an alloy analyzer.
304 vs 316 at a glance
| 304 | 316 | |
|---|---|---|
| Family | Austenitic | Austenitic |
| Chromium | 17.5–19.5% | 16–18% |
| Nickel | 8–10.5% | 10–14% |
| Molybdenum | None | 2–3% |
| Pitting resistance (PREN) | ~18–20 | ~23–25 |
| Chloride resistance | Good | Much better |
| Tensile strength (annealed, min.) | 515 MPa (75 ksi) | 515 MPa (75 ksi) |
| Yield strength (annealed, min.) | 205 MPa (30 ksi) | 205 MPa (30 ksi) |
| Magnetic? | No, but can become slightly magnetic when bent or formed | No, and stays non-magnetic more reliably |
| Weldability | Excellent (filler 308L) | Excellent (filler 316L) |
| Food safe? | Yes | Yes |
| Relative price | Baseline | Typically ~20–40% higher |
| Other names | UNS S30400 · EN 1.4301 · SUS304 · “18/8”, “A2” | UNS S31600 · EN 1.4401 · SUS316 · “marine grade”, “A4” |
Composition and mechanical values are ASTM A240 limits for plate, sheet and strip. Bar and other product forms have slightly different limits.
The one real difference: molybdenum
Both grades protect themselves with a thin chromium-oxide passive layer. Chloride ions, from sea salt, road salt, pool chlorine, sweat, many cleaners and some foods, can break that layer at weak points. That causes pitting (tiny deep holes) and crevice corrosion (in tight gaps such as under washers and in joints).
The molybdenum in 316 makes the passive layer much harder for chlorides to break through and quicker to repair. That’s why its PREN, a standard measure of pitting resistance, is about 5 points higher than 304’s. In daily life this means:
- Near the coast, 304 railings and fittings often develop brown “tea staining” within months, while 316 stays bright much longer.
- For drinking and process water, a common guideline is that 304 handles up to roughly 200 mg/L of chlorides, and 316 up to roughly 1,000 mg/L, at ambient temperature. Hot water lowers both limits.
- In salty or acidic food processing (brines, tomato sauce, pickles), 316 is the safer long-term choice.
Neither grade is “rust-proof”. 316 also stains if salt deposits are left on it, especially on rough finishes. A smooth finish and regular rinsing matter almost as much as the grade. More in can stainless steel rust? and does stainless steel rust in water?
Strength, heat and physical properties
In everyday terms, 304 and 316 are equally strong, with the same minimum tensile and yield strength in the annealed condition. Both have excellent toughness down to very low temperatures, and both resist oxidation in air up to roughly 870 °C (1600 °F) in intermittent use and 925 °C (1700 °F) continuous. They have similar density (about 8.0 g/cm³) and similar heat conduction. 316 expands slightly less with heat.
So if strength or temperature is the deciding factor, the grade choice won’t change much. Look at duplex (e.g. 2205) for more strength, or 309/310/321 for high-temperature service. See 2205 vs 316 and 304 vs 321.
Fabrication: cutting, bending, welding
- Forming and bending: both form well. 304 is slightly easier to deep-draw (stretch into deep shapes like sinks), which is one reason most sinks and cookware are 304.
- Welding: both weld very well. Use 308L filler for 304 and 316L filler for 316. For thick sections or heavy welding, choose the low-carbon L grades (304L, 316L) to keep full corrosion resistance at the welds. See 304 vs 304L, 316 vs 316L and stainless welding techniques.
- Machining: both are “gummy” and work-harden. 316 is a little tougher on tools. If you machine a lot of parts and don’t need to weld, 303 is easier than either.
- Keep it clean: on both grades, rust spots after fabrication almost always come from iron contamination (steel dust, carbon-steel brushes), not from the grade itself.
Cost: is 316 worth it?
316 usually costs about 20–40% more than 304 for the same sheet, plate or tube. The gap moves with nickel and molybdenum prices, because mills add a monthly alloy surcharge that tracks those metals. The upgrade pays for itself when:
- the part is outdoors within a few miles of the sea, or near road salt,
- it’s in or around pools, spas or chlorinated water,
- it touches salty or acidic products every day (food processing, chemicals, pharma, medical),
- it’s hard or expensive to replace (structural fixings, hidden fasteners, boat fittings),
- it has crevices or tight joints where salty water can sit.
It’s usually not worth it for indoor kitchens, appliances, inland architecture, furniture, or decorative work that’s easy to clean.
Which one for your project?
| Application | Pick | Why |
|---|---|---|
| Kitchen backsplash, counters, sinks | 304 | Indoor, cleaned often. 316 adds cost without real benefit. |
| Cookware, cutlery, water bottles | 304 (18/8, 18/10) | Food-safe and durable. “316 cookware” gives little practical gain for home cooking. |
| Commercial food processing (brine, sauces, dairy cleaning chemicals) | 316/316L | Salts, acids and chlorinated sanitizers |
| Inland outdoor railings, signage, furniture | 304 | Fine with occasional cleaning |
| Coastal railings, balconies, cladding (within ~5 miles / 8 km of the sea) | 316 | Salt spray causes tea staining on 304 |
| Boat hardware, docks, marine fasteners | 316 / 316L (duplex for submerged or structural parts) | Constant salt exposure |
| Swimming pool ladders, rails, outdoor showers | 316 | Chlorides from pool water. For load-bearing parts in indoor pool halls, ask a specialist, because special grades may be required. |
| Bolts and screws | A2 (304) inland, A4 (316) coastal or marine | Fasteners have crevices, so the extra resistance helps |
| Medical devices, implants, body jewelry | 316L | Better corrosion resistance in the body. Often called “surgical steel”. |
| Chemical and pharmaceutical equipment | 316L (or higher alloys) | Chlorides, acids and cleaning chemicals |
Ordering sheet? See stainless steel sheet metal: grades, gauges, finishes & sizes and the stainless steel gauge chart. Fasteners: stainless steel A2 (and A4).
How to tell 304 from 316
They look and feel identical, and a magnet won’t help: both are essentially non-magnetic. Reliable options:
- Paperwork: the mill test report (MTR) or stencil marking on sheet and plate states the grade and chemistry.
- Molybdenum spot test: an inexpensive chemical kit. A drop of reagent changes color on 316 (with molybdenum) and not on 304.
- Handheld XRF analyzer: reads the alloy in seconds without damaging it. Scrap yards and metal suppliers often have one.
- Stamped markings on fasteners and fittings: “A2” or “304” versus “A4” or “316”.
Frequently asked questions
Is 316 stainless better than 304?
It’s better at resisting corrosion from salt, chlorides and many chemicals. It isn’t stronger, harder or better looking. For most indoor and inland uses, 304 performs just as well for less money.
Can 304 stainless be used outdoors?
Yes. Inland, in normal city or rural air, 304 does well outdoors with occasional cleaning. Near the sea, near de-icing salt, or in polluted industrial air, choose 316 or plan for more frequent cleaning.
Does 316 stainless rust?
It can stain or pit if salt deposits, dirt or iron particles are left on it for long periods, especially on rough finishes or in crevices. It’s much more resistant than 304, but rinsing and cleaning still matter.
Is 316 stainless magnetic?
No. Annealed 316 is non-magnetic and stays that way after forming better than 304, which can pick up slight magnetism when bent or cold worked. See stainless steel and magnets.
Is 304 or 316 better for food?
Both are food-safe. 304 is the standard for kitchens, cookware and most food equipment, while 316 is preferred where foods or cleaning chemicals are salty or acidic. See is stainless steel non-toxic?
What’s the difference between 316 and 316L?
316L has lower carbon (≤0.03%). That keeps welded areas fully corrosion resistant, so it’s the usual choice for welded and medical parts. Much material today is dual-certified 316/316L. Details in 316 vs 316L.
Is 18/8 stainless the same as 304?
Essentially, yes. “18/8” (18% chromium, 8% nickel) is a common label for 304-type steel in cookware and fasteners. “18/10” is also 304-type steel, just with a little more nickel, so it isn’t 316. 316 is usually labeled “316”, “marine grade” or “A4”. See 316 vs 18-8.
For the bigger picture on all grades, read stainless steel types and grades.
Last updated: October 2026. Composition and strength values are from ASTM A240. Chloride guidelines follow published Nickel Institute guidance for water systems. Prices vary with alloy surcharges. Always confirm grade requirements with your supplier or engineer for critical applications.
