The Economist (reference below) defines variable costs as the part of a firm’s production costs that changes according to how much output it produces, and adds:
“Examples include some purchases of raw materials and workers’ overtime payments. In the long run, most costs can be varied.”
Wikipedia (reference below) notes that:
“Variable costs are also the sum of marginal costs over all units produced.”
“Variable costs are sometimes called unit-level costs as they vary with the number of units produced.”
“The level of variable cost is influenced by many factors, such as fixed cost, duration of project, uncertainty and discount rate.”
Atlas topic, subject, and course
The Economist, Variable costs, Economics A-Z, at http://www.economist.com/economics-a-to-z/v#node-21529396, accessed 7 May 2016.
Wikipedia, Variable cost, https://en.wikipedia.org/wiki/Variable_cost, accessed 1 June 2017.
Page created by: Ian Clark, last modified 1 June 2016.
Image: Wikipedia, Fixed cost, https://en.wikipedia.org/wiki/Fixed_cost, accessed 1 June 2017.