Definition: Actual Cost - Explained
The amount that is paid for an item or service is considered to be the actual cost. It is the price incurred, such as at the retail store register or website checkout form.
The actual cost may vary with an estimated cost. Although estimated and actual costs are most near each other when the item is standardized, everything else being equal.
Always leave room between any projected or estimated sums and for those that will actually be incurred. Also it might help to take additional factors into account, like the time to buy along with any potential price rises and declines, any changes in supply and labor and natural resources used in the production cycle and for unforeseeable elements in general.