Prime Rib Calculator — How Much Standing Rib Roast to Buy
Enter your headcount, cooked prime rib per person, and bone-in or boneless. The calculator totals the cooked roast needed and divides by the typical edible yield (bone-in ~50% after bone and shrinkage; boneless ~75%, no bone) to find the roast size to buy. Quantity planning only — no doneness or cooking guidance.
What this calculator determines
It estimates the standing rib roast to buy for a crowd by totaling the cooked prime rib needed and dividing by an adjustable edible yield for bone-in or boneless.
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Examples
12 people, bone-in, ½ lb each
12 people, 0.5 lb cooked each, bone-in (50% edible)
Calculation
- Cooked = 12 × 0.5 = 6 lb
- Roast to buy = 6 ÷ 0.50 = 12 lb
≈ 12 lb bone-in roast
Assumptions & Conventions
- Edible yield is a variable planning estimate
- The default is ~50% edible for bone-in (shrinkage plus bone) and ~75% for boneless; actual yield varies by roast, cooking method, and doneness, and is user-adjustable.
- Servings per person is a default you can change
- The calculator starts with a default of ½ lb cooked per person, which you can change; it is not a universal recommendation.
- Quantity planning only
- It provides purchase quantity only — no doneness, cooking, or carving guidance.
- No purchase rounding
- The roast size is calculated to two decimals, not rounded to a whole-pound purchase size.