Modern farming has become very energy intensive. There is a great need to balance the use and availability of energy, especially in the agricultural sector, in such a manner so as not to affect production adversely. A study was conducted to optimise the energy inputs for the cotton crop in Punjab. Different mathematical functional relations were fitted between the yield and total energy input. An attempt was also made to optimise the energy inputs using frontier production functions (unconstrained frontier function and constrained frontier function). Seedbed preparation, irrigation and weeding consumed about 70% of the total energy input. The average yield of cotton can be increased by 6-8% with an additional energy input of 1-3%, mainly through tillage, irrigation and spraying.