Labor and material costs are also directly proportionate to sales. These are things that go directly into the making of the product or into doing the service. a. Labor cost is the actual direct labor used in the making of product or doing the service. The cost would also include all the fringe benefits like social security, payroll taxes, vacation pay, holidays, sick pay days, etc. b. Material costs are all the materials used in the making of product or in doing the service. In the lawn mower service as an example it would be the gasoline used in the mower and any other materials used directly in that service. For producing a product it would be all the materials used in the product that is sent to the customer including all the packaging materials.
Besides, your friends may be 100% behind you in your new venture, but, in case you are hoping to involve others who have actual money to invest, you may need to be able to make a convincing case. Wouldn't it be nice to have anticipated possible questions and be ready with plausible answers? If you are risking your own money, that is perhaps even a stronger reason to do some indispensable planning.