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

18/8, 18/10, and 18/0 describe how much nickel is in the steel, not how good it is. 18/8 and 18/10 both fall inside the same AISI 304 specification — 18% chromium plus a nickel share the standard allows to range roughly from 8% to 10.5% — while 18/0 swaps that nickel out entirely for AISI 430, a magnetic, more rust-prone grade. Two other names matter for kitchen shopping: 201 substitutes manganese for most of the nickel to cut cost, and 316 adds molybdenum for extra resistance to salt. None of the five is dangerous. What changes between them is rust resistance, whether a magnet sticks, and how much nickel and chromium can migrate into acidic food over a long, hot cook.

None of this is a reason to replace what’s in the cupboard. The difference these numbers describe is corrosion resistance across years of acid and salt, not a safety line, and the leaching study below measured long, repeated, acidic cooking, not a bowl of water or a five-minute pan. An unmarked “stainless” piece earns retirement when it has actually pitted or rusted through at a seam.

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 names cover almost everything sold as “stainless” in a kitchen aisle. The chromium and nickel figures below come from the composition standards behind each AISI designation, not from any single product’s marketing copy.

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 — see the note on what the “10” actually verifies below
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 our checks across this site’s dog bowl and lunch box coverage, 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. 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. The related question “304 vs. 316 stainless steel” shows up in general materials searches far more than kitchen-specific ones for exactly this reason — most of that demand is industrial and marine, not culinary.

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. Checking maker pages across this site’s own coverage turned up 201 quietly doing the job 304 gets credit for in a handful of categories: 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. Our colander check found the opposite pattern in that category: most colanders checked didn’t state a grade at all, and only one maker did.

Makers That State Their Grade

The products below all name a specific stainless grade on the maker’s own product or materials page — not a retailer listing or a customer question — reused from checks already run across this site’s stainless steel colander, dog bowl, lunch box, rice cooker, and kettle coverage.

Product	Category	Grade stated	Where stated
Tramontina 3-Pk Stainless Steel Colanders	Colander	18/8 (304)	tramontina.com
Basis Pet Stainless Steel Dog Bowl	Dog bowl	304 (18/8)	basispet.com
YETI Boomer 8 Dog Bowl	Dog bowl	18/8 (304)	yeti.com
PlanetBox Rover (our lunch box check)	Lunch box	Tray 18/8 (304); lid 18/0 (430)	planetbox.com
LunchBots Large Trio	Lunch box	18/8	lunchbots.com
ECOlunchbox Three-in-One	Lunch box	201	ecolunchboxes.com
Monbento MB Sense	Lunch box	18/8	us.monbento.com
Elephant Box	Lunch box	304	elephantbox.co.uk
Instant Pot Duo 6-Qt inner pot	Rice cooker / multicooker	304 (18/8)	instantpot.com
Tatung TAC-11KN	Rice cooker	18/8 (304)	us.tatung.com
Aroma Select Stainless (ARC-753SGB/ARC-757SG)	Rice cooker	304	aromaco.com
Buffalo Classic Rice Cooker	Rice cooker	SUS304/SUS439 clad	buffalocookware.com
Fellow Stagg EKG	Electric kettle	304	fellowproducts.com
Chantal Mia Ekettle	Electric kettle	18/8	chantal.com

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 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.

Where This Fits in Our Kitchen Coverage

If you’re shopping for a specific item rather than the grade itself, our stainless steel dog bowl check, colander check, and lunch box check run this same grade-by-grade audit against each maker’s own page for that category. Our non-toxic rice cooker guide and plastic-free electric kettle guide cover inner-pot and water-path grades specifically. For material trade-offs beyond stainless, our non-toxic cookware brands guide runs the same material-first check across stainless, cast iron, enameled cast iron, and ceramic-on-aluminum options by brand.

The same grade question applies to water bottles, where the lid rather than the body is usually the weak point — see why the lid is what matters for what to check before buying.