Context Pork belly is the most preferable and expensive primal cut among various primal cuts in Korea. Aim The aim of this study was to investigate the relationship of pig carcass grade with the amount of pork belly (kg). Methods In total, 350 179 Landrace, Yorkshire, and Duroc (LYD) pigs were graded with the Korean Pig Carcass Grade System. Amount of pork belly cut was estimated with an AutoFom III equipment. Key results Distribution characteristics of carcass weight, backfat thickness, belly weight, and belly fat percentage were analysed. When the yield of pork belly was investigated by grade, lower-grade carcass had a higher amount of pork belly (P < 0.0001). The correlation coefficients between carcass weight and belly weight were 0.798 for Grade 1+, 0.906 for Grade 1, and 0.932 for Grade 2 (P < 0.0001). The correlation between backfat thickness and belly weight was lower with a decreasing grade. Regression analysis was performed with carcass weight or backfat thickness as a dependent variable and belly weight as an independent variable. Coefficients of determination (?2) of carcass weight and belly weight for each grade were higher for a lower grade (0.637 for Grade 1+, 0.821 for Grade 1, 0.867 for Grade 2). Conclusion The lower-grade pork belly, the most expensive in Korea, had a higher quantity of pork belly, and the correlation coefficient between pork belly and carcass weight and between pork belly and backfat thickness was higher as the lower grade level increased. Implication For a reasonable price of pork in the market, the current lean meat-based carcass-grading system should also include the yield of each primal cut.