The difference between a lip-on and a lip-off ribeye is a strip of meat and fat called the lip: lip-on (IMPS 112A) keeps a tail of intercostal meat and fat attached along the ribeye roll, and lip-off (IMPS 112, sometimes just called the trimmed ribeye roll) has that strip removed, leaving closer to pure eye. Same primal, same muscle, meaningfully different product and price.
What the lip is
Fabricators break the rib primal down to the ribeye roll, the cylinder of muscle a ribeye steak comes from. Along one side of that cylinder runs a strip of intercostal meat and fat, the lip. Leave it attached and you have the 112A lip-on roll, the workhorse spec for steakhouse and retail programs that want the classic ribeye shape with the fat that carries flavor through a sear. Remove it and you have the 112, a tighter, leaner roll that portions into cleaner rounds with less trim loss at the cutting board.
Why the same word covers a wide price spread
When a price sheet, a broker, or a report says "ribeye" without a spec, it can mean at least four different products: boneless lip-on (112A), boneless lip-off (112), and the bone-in lip-on family (IMPS 109 codes, including the export-style version), which is the steakhouse and tomahawk raw material. These trade at genuinely different levels because the buyer is paying for different ratios of eye, lip, bone, and trim work. On the USDA prints, boneless lip-on ribeye also splits into weight brackets: heavy is 11 pounds and up, light is under 11, same 112A spec, different carcass size behind it. Heavy cuts bigger steaks; which bracket trades premium moves with what steakhouse and retail programs are speccing.
How to read a quote
The discipline is simple: never accept or compare a ribeye quote without the spec attached. A lip-off number against a lip-on number is not a spread, it is two different products, and a bone-in number against either is a third. The same trap runs through USDA reporting and through any tool built on it, which is why every ribeye line on this site carries its IMPS code and spec next to the price. If a quote lands in your inbox saying just "ribeye," the first reply is always the same question: which one.