SS Vs. SUS Is There a Difference?

Scientists and engineers have a habit of giving weird names to things, or at least struggling to align them universally.

Acronyms and abbreviations lend themselves to being not exactly reader friendly.

Abbreviations for stainless steel are no different. A common question we see on metalworking forums is “SS vs. SUS: What the heck is the difference?”

If you don’t know the answer, don’t feel bad — it’s not exactly an easy question. And the answer is a little ambiguous.

Let’s dissect what makes these two stainless steel designations the same — and different.

SS Vs. SUS: What Do They Mean?
As you may have guessed, “SS” is the abbreviation for “stainless steel.” It’s the American way of listing steel grades (ex: SS grade 316).

“SUS,” on the other hand, is the typical Japanese Industrial Standards (JIS) designation for stainless steel grades. It stands for “steel use stainless.”

Despite the difference of one letter in these stainless steel abbreviations, American and Japanese steel grades still line up identically.

For instance, let’s say you need to order 316 grade stainless steel — one of the strongest and most corrosion-resistant metals on the market. If you were to put “SS 316” and “SUS 316” on your order form, you’d be specifying the same metal twice. You’d end up getting that same versatile alloy of chromium and nickel.

Despite many different systems existing globally, most of them use the same numbers for the common grades, like 316 and 304. That said, if you use the term “SUS,” you risk your vendor failing to understand what you’re looking for. It’s better to just say “stainless steel.”