18/8 vs 18/10 Stainless Steel: What the Numbers Mean

For a kitchen, 18/8 and 18/10 are the same steel. Both fall inside the AISI 304 specification, which allows roughly 8% to 10.5% nickel alongside 18% chromium, and the British Stainless Steel Association says the “10” on most commercial cookware does not indicate an actual higher nickel content. (One materials guide reads it more kindly, as the high-nickel end of that range.) Either way, paying more for 18/10 buys a number, not better steel.

The grades that change what you get are the ones labels mention less. 18/0 (AISI 430) has no nickel and rusts sooner under acid and salt, which is why it belongs on handles and lids. 201 swaps most of the nickel for manganese to cut cost and sometimes sits behind a plain “stainless steel” label on budget bowls, bottles and lunch boxes. 316 adds molybdenum and earns its premium only around salt.

None of this is a reason to replace what’s in the cupboard: the grades differ in how they resist corrosion over years, not in safety, and an unmarked “stainless” piece earns retirement only when it has pitted or rusted through at a seam. Nickel does move into food. A 2013 study measured it rising in tomato sauce cooked for hours in new stainless pans, with the transfer falling after about six cooking cycles, but that is long, acidic, repeated cooking, not a glass of water. When you buy, a named 304 is the grade to pay for on anything that holds wet or acidic food for hours. Whatever the grade, a worn-out piece is one alloy, with no coating or resin to separate once the gasket or plastic lid comes off.

What 18/8, 18/10, 18/0, and 201 Mean

The slash numbers on stainless cookware, flatware, and bottles are a shorthand for the alloy’s chromium and nickel content by weight. 18/8 means 18% chromium and 8% nickel — the composition that defines AISI 304, the most common food-grade stainless steel. 18/10 names the same 304 family, marketed with a nickel figure at the higher end of that specification’s allowed range. 18/0 drops nickel to zero and corresponds to AISI 430, a different steel family (ferritic rather than austenitic) with the chromium’s rust resistance but none of nickel’s added corrosion protection. 316 keeps roughly the 304 recipe and adds 2–3% molybdenum, which specifically improves resistance to pitting from chloride — salt water and brine. And 201 is a lower-cost workaround: it keeps chromium near 16–18% but substitutes manganese for most of the nickel, landing at 3.5–5.5% nickel instead of 304’s 8–10.5%.

Is 18/8 or 18/10 Better?

For a kitchen, the practical difference is small. Both names map to the AISI 304 specification — 18% chromium plus a nickel share the standard allows to range from about 8% up to roughly 10.5%. The British Stainless Steel Association, a metallurgy trade body, states plainly that the “10” in 18/10 “does not indicate an actual higher Ni content” in most commercial cookware and calls it closer to a marketing label than a distinct alloy. A separate materials guide describes 18/10 as sitting at the higher-nickel end of that same 304 range, which is the more charitable reading. Either way, both are the same base grade with good everyday corrosion resistance — the number on the box is not a reliable way to pay more for meaningfully better steel.

Stainless Steel Grades at a Glance

Five grades cover almost everything sold as “stainless” in a kitchen aisle, and they sort by one thing: how much nickel is doing the rust-proofing. Only 18/0 is magnetic enough for a fridge magnet to identify, and only 316 is built for salt.

Grade	Common name	Chromium / nickel	Magnetic?	Corrosion resistance	Typical kitchen use	Price signal
18/0	AISI 430 (ferritic)	~17–18% chromium, 0% nickel	Yes, strongly — the one grade a fridge magnet reliably identifies	Lowest of this group; no nickel to slow rust under acid or salt	Cheap flatware, decorative trim, some sink basins, lunch-box lids (paired with an 18/8 tray)	Least expensive
201	Low-nickel austenitic (no direct 300-series equivalent)	16–18% chromium, 3.5–5.5% nickel, 5.5–7.5% manganese substituted for the rest	Often mildly magnetic after stamping or rolling, but not a reliable test on its own	Lower than 304; more prone to rust and pitting over years of acid or salt contact	Budget dog bowls, bottles, and lunch boxes — sometimes sold as plain “stainless steel” with no grade stated	Cheapest grade still called austenitic stainless
18/8	AISI 304	18% chromium, 8% nickel	No, or only very weakly where the metal was cold-worked	Good in ordinary kitchen use — the workhorse grade for food contact	Most cookware, bottles, bowls, and lunch boxes that do name a grade	Mid-range; the most common “quality” tier stated on maker pages
18/10	Also AISI 304	18% chromium, marketed as 10% nickel	No	Marketed as superior to 18/8; falls in the same 304 specification range	Flatware and premium cookware marketing more than everyday kitchen tools	Marketed as premium, though the “10” doesn’t reliably mean more nickel
316	AISI 316 (“surgical” or marine grade)	16–18% chromium, 10–14% nickel, plus 2–3% molybdenum	No	Highest of the five — molybdenum resists pitting from salt and acid	Some water bottles and high-end cookware marketed on durability; less common in everyday kitchenware	Highest premium

What Changes for a Kitchen Buyer

Three things move between these grades in ordinary use: whether a magnet sticks, how fast the metal corrodes under acid or salt, and how much nickel and chromium can migrate into food during long, acidic cooking. The magnet test is the one home check worth trying, with a real limit — it reliably flags 18/0 (strongly magnetic) but can’t distinguish 201 from 304 with confidence, since both are nominally non-magnetic austenitic steels that sometimes pick up mild magnetism from cold-forming.

Is 18/0 Stainless Steel Safe for Food?

Yes. 18/0 — AISI 430, the ferritic grade with no nickel — is safe for ordinary food contact and is what most stainless flatware handles and some lunch-box lids are made from. The trade-off is corrosion resistance, not safety: without nickel to help form a stable passive layer, 430 rusts and pits faster than 304 under prolonged acid or salt exposure, which is why it shows up more in dry-contact parts like handles and lids than in pots that hold acidic sauce for hours. It’s also the one grade a kitchen magnet identifies reliably — 430 is strongly ferromagnetic, unlike 304 or 316.

Is 201 Stainless Steel Toxic?

No, but it corrodes faster than 304 and is the grade most likely to go undisclosed on a budget product listing. 201 is a real, standardized austenitic stainless steel — 16–18% chromium, 3.5–5.5% nickel, with manganese substituted for the nickel content 304 uses — not a toxic substitute metal. The practical issue is durability and disclosure: lower nickel means less corrosion resistance over years of acid or salt contact, and sellers marketing a bowl or bottle as plain “stainless steel” without naming a grade are, in the dog bowl and lunch box listings covered on this site, sometimes using 201 rather than 304 underneath that word.

Does Stainless Steel Leach Nickel?

Yes, measurably, and acidic food increases it. A 2013 study in the Journal of Agricultural and Food Chemistry cooked tomato sauce in stainless steel pans for cooking times up to 20 hours and compared it against sauce cooked without stainless contact. After six hours, nickel concentrations rose up to 26-fold and chromium up to 7-fold, depending on the steel grade; at the longest cooking times measured, nickel rose about 34-fold and chromium about 35-fold. New cookware leached the most, and the effect dropped after roughly six cooking cycles, though the tenth cycle still transferred an average of 88 micrograms of nickel and 86 micrograms of chromium into a 126-gram serving of sauce. That’s a real, measured effect from long, acidic, repeated cooking — not evidence that a five-minute stir-fry or a glass of water in a stainless bottle poses the same exposure.

Nickel allergy is separately common — dermatology sources describe it as one of the most frequent causes of contact dermatitis. But DermNet NZ, a dermatology reference, is specific that “stainless steel does not usually cause dermatitis unless it is nickel-plated” — the reactions most people associate with nickel-sensitive skin come from nickel-plated jewelry and hardware, not solid stainless cookware. A razor is one of the personal items DermNet lists as a possible nickel source, and the safety razor comparison lists the metal each maker names. The leaching study above measured nickel entering food, which is a dietary exposure question; a contact skin reaction from touching a stainless pan handle is a different and much less common event.

When Does a Kitchen Need 316 Stainless Steel?

Mainly for salt exposure, not everyday cooking. 316 adds 2–3% molybdenum on top of the 304 recipe, and that addition specifically improves resistance to pitting from chloride — salt water, brining liquid, coastal humidity — more than it changes how the steel behaves against an ordinary tomato sauce or a squeeze of lemon. A water bottle that travels to the beach or a stockpot used for brining benefits from it measurably; a saucepan, colander, or lunch box used at home for typical cooking doesn’t see enough of that specific chemistry for 316 to change the outcome versus a well-made 304 piece. On a water bottle, though, the lid is usually the weak point rather than the steel, which our non-toxic water bottle guide explains.

Where Cheap “Stainless” Hides

The word “stainless steel” on a product listing doesn’t obligate a seller to name a grade, and plenty don’t. In a few categories, 201 quietly does the job 304 gets credit for: a budget dog bowl, a kids’ bento box, and similar low-price bottles all sometimes use 201 rather than 304 underneath a generic “stainless steel” label. None of that makes the product unsafe — 201 is standardized, food-contact steel, not a substitute metal — but it does mean the grade, and the corrosion resistance that comes with it, is often lower than a shopper assumes from the word alone. Colanders are the opposite case: in our stainless steel colander guide, none of the makers’ own pages names a grade, and the one set that states 18/8 does so only on its Amazon listing.

Makers That State Their Grade

Most of these name 304 or its 18/8 label. ECOlunchbox’s Three-in-One is the one that names 201, and PlanetBox pairs an 18/8 tray with an 18/0 lid. The rice cooker rows give the inner pot’s grade; our non-toxic rice cooker guide compares those pots in more detail. Toasters rarely come with a grade at all; Keenstone, which claims 18/8 steel on every surface the bread touches, is the exception in our non-toxic toaster guide.

Product	Category	Grade stated
Basis Pet Stainless Steel Dog Bowl	Dog bowl	304 (18/8)
YETI Boomer 8 Dog Bowl	Dog bowl	18/8 (304)
PlanetBox Rover (lunch box guide)	Lunch box	Tray 18/8 (304); lid 18/0 (430)
LunchBots Large Trio	Lunch box	18/8
ECOlunchbox Three-in-One	Lunch box	201
Monbento MB Sense	Lunch box	18/8
Elephant Box	Lunch box	304
Instant Pot Duo 6-Qt inner pot	Rice cooker / multicooker	304 (18/8)
Tatung TAC-11KN	Rice cooker	18/8 (304)
Aroma Select Stainless (ARC-753SGB/ARC-757SG)	Rice cooker	304
Buffalo Classic Rice Cooker	Rice cooker	SUS304/SUS439 clad
Fellow Stagg EKG	Electric kettle	304
Chantal Mia Ekettle	Electric kettle	18/8

Grades as each maker states them on its own product or materials page (August 2026).

For buying once, the rule that falls out of that list is narrow. Pay for a named 304 wherever the item holds wet or acidic food for hours — a stockpot, a stainless slow cooker insert, a dog bowl, a lunch box base — because corrosion ends a stainless product’s life, and no care routine turns 201 into 304. Pay for 316 only where salt is involved. Leave 18/0 where it already sits, on handles, lids, and dry-contact parts. Whichever grade, stainless ends better than the materials it competes with: one alloy, no coating to delaminate and no resin to identify, so a piece that finally rusts through is just itself once the gasket, plastic lid, or rubber base ring comes off. If a coated pan is still on the shortlist, our PFAS-free cookware guide shows which coating claims rule out PTFE and which stop at PFOA.