The study was conducted in the year 2016–2017 to study the “economics of onion in Vijayapur district of Karnataka state” with a sample of 120 respondents. It revealed that, the cost of cultivation for small, medium and large of farms groups were Rs. 72,123/ha, Rs. 64,965/ha and Rs. 60,705/ha, respectively. Average cost of cultivation in different size farms group was Rs. 66, 274/ha. The gross returns obtained per hectare by small size farms were high (Rs.1,90,000/ha) as compared to medium and large size farms (Rs.1,80,000/ha and Rs.1,60,000 /ha, respectively). Net returns per hectare were highest in small size farms (Rs.1, 17,877/ha) compare to the medium and large size farms (Rs. 1,15,035/ha and 99,295/ha). Cost A1 was highest in small size farms (Rs. 50,176/ha) followed by medium size farms (Rs. 48,718/ha) and lowest in large size farms (Rs. 46,558/ha), respectively. Cost A2 in small, medium and large size of farms groups was Rs. 50,176/ha, Rs. 48,718/ha and Rs. 46,558/ha, respectively. Cost B was highest in small size farms (Rs. 62,073/ha) as compared to medium size farms (Rs. 58,455/ha) and in large size of farms (Rs.58,455/ha) respectively. Cost C was highest in small size farms (Rs. 72,123/ha) and lowest in large size farms (Rs. 60,705/ha). Farm business income in small, medium and large size of farms group was Rs. 1,39,824/ha, Rs. 1,31,282/ha and Rs. 1,13,442/ha, respectively. Farm investment income was highest in small size farms (Rs. 1, 29,774/ha) as compared to medium size farms (Rs. 1, 26,932/ha) and lowest in large size farms (Rs. 1,11,192/ha), respectively. Family labour income was Rs. 1,27,927/ha for small size farms group, Rs. 1,21,545/ha for medium size farms group and Rs. 1,00,309/ ha for large size of farms group.