All our cost measures including total cost, fixed cost, variable cost, marginal cost, average cost have a time dimension. They are denominated in units of currency per unit of time. For a monthly budget, the cost units would be dollars per month. Here's the total cost per month of providing different numbers of screening mammograms per day. This study was done just after Medicare started paying for screening mammograms.
Total cost graphed Sound applet Total cost is an increasing function of quantity.
Usually, the more your produce, the more your total cost. The cost of producing 0 output in a given time period. First let's do the fixed cost associated with the capital outlay. The capital outlay is a lump of money we need before we start. The capital outlay is a stock, really, rather than a flow.