You can build your own custom module for this requirement . You can proceed in these ways: You should first inherit mrp.bom and add a new field 'price_unit': fields.float('Unit Price') and redefine the onchange_product_id function define compute_price and compute_total function to calculate "line price" and "total price" Then you have to inherit mrp.production and define compute_production_cost function to update cost_price from BOM. We have created this custom module and it works perfect , in my module it takes avg purcahse price in BOM and we added an extra tab to manufactring form to compute Production Cost , in that tab you can add extra charges like electicity etc.. , that charges also added to cost by calculating per_unit charge depending on UOM. for any help you can contact: baijuks@hotmail.com