Depending on the type of resources costs will be calculated in different ways.
For labor resources, the cost is made up of estimation multiplied by the cost per hour.
Example: A resource’s cost per hour is $8, and s/he works 10 hours on a task. The cost is 8x10 that equals $80.
For material resources, the cost is made up of the number of items you indicate (which is zero by default) multiplied by cost per item.
Example: A material resource’s cost per item is $10. If we assign 10 items of this material resource to a task, then the cost will be 10x10, $100.
For resources with fixed costs, the cost should be indicated manually when you assign the resource to a task (i.e. any fixed sum like $284, for example).
Per hour
The actual cost takes the values from the Time log field for project participants. For virtual resources it is connected to the task progress.
Per item
The actual cost is directly connected to the task progress.
Fixed cost
The actual cost is directly connected to the task progress.