The difference between 18/8 and 18/10 stainless steel comes down to one number: nickel. Both alloys contain roughly 18% chromium, but 18/8—also known as Grade 304—has about 8% nickel, while 18/10 has about 10%. That extra 2% buys you measurably better resistance to acidic drinks, a shinier finish, and a higher price tag. If you carry only plain water, 18/8 is generally the smarter buy; if lemon water, coffee, or tea is a daily habit, 18/10 earns its premium.
Understanding Stainless Steel Grades: 18/8 vs. 18/10
The numbers in these designations are not marketing codes—they are composition figures. The first number, 18, refers to approximately 18% chromium, which is what makes steel "stainless" by forming a corrosion-resistant surface. The second number is the nickel percentage: 8% for 18/8 and 10% for 18/10.
Here is where it gets simpler than the labels suggest. Writing for the bottle manufacturer Haers, a materials explainer notes that 18/8, 304, and SUS 304 all refer to the same food-grade alloy containing approximately 18% chromium and 8% nickel. So if your bottle says "304" and a friend's says "18/8," you are holding the same steel called by different industrial naming traditions.
18/10 sits one notch above it. Materials suppliers describe it as containing approximately 18% chromium and 10% nickel, with that additional nickel improving corrosion resistance, durability, and surface appearance. Additive Plus, an industrial materials supplier, calls the compositional difference small but notes the extra nickel can deliver noticeable improvements, especially in demanding environments.
