India is second large vegetable grower at global level, trailing only China. Onion is main vegetable crop of Maharashtra more than half of the country yield comes from Maharashtra. The present research was to investigate the economics of onion production on farms of various sizes. The research was carried out in the Nashik district (2016-17), which was chosen due to the largest onion growing area in Maharashtra. A survey was undertaken to collect the opinions of 131 farmers from various farm sizes, which were chosen according to the probability proportion to the number of farmers from each size farm group. Area and yield were typically used to calculate production data. Onion is important cash crops so production takes significantly more capital than other crops. As a result, caution is required. On average, Rs. 69325.01 was spent per hectare on onions. Small farms had the greatest cultivation costs, at Rs. 72559.57, followed by medium size farms (Rs. 69174.81) and large size farms (Rs. 66240.66). Large size farmers had higher net returns per hectare (Rs. 45,970.94/ha) than medium and small size farmers (Rs. 43,248.49/ha and Rs. 45,445.94/ha, respectively). Large size farms had the highest benefit/cost ratio (1:1.69) followed by medium size farms (1:1.63) and small size farms (1:1.58). As a result, the sample average Benefit/Cost ratio in various farm sizes was 1:1.63.