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How does ProjeX calculate costs?
From version 97.1 and on ProjeX has the ability to allocate daily hours to both tasks and resources, eg. a certain resource might be able to work eight hours a day Monday to Thursday but only four hours on Fridays and Saturdays and none on Sunday. Likewise tasks can have hours allocated to specific days, eg. Monday to Friday tens hours a day but Saturday and Sundays zero. The 'available hours' that the resource can work on the task are defined as which ever is the smaller between the task hours and the resource hours.
Lets look at the first case where we define the cost of the resource per hour, for the example below lets say the cost of the resource is $45 an hour.
| Mon | Tue | Wed | Thur | Fri | Sat | Sun | Total hours |
Total Cost |
|||
| Res. Hours | 8 | 8 | 8 | 8 | 4 | 4 | 0 | 40 | |||
| Task Hours | 10 | 10 | 10 | 10 | 10 | 0 | 0 | ||||
| Available Hours |
8 | 8 | 8 | 8 | 4 | 0 | 0 | 36 | |||
| Costing for an allocation of 30 hours |
Hours to allocate | 6.5 | 6.5 | 6.5 | 6.5 | 4 | 0 | 0 | |||
| Daily Cost | 292.5 | 292.5 | 292.5 | 292.5 | 180 | 0 | 0 | ||||
| Accrued Cost | 292.5 | 585 | 877.5 | 1170 | 1350 | 1350 | 1350 | 1350 | |||
| Costing for an allocation of 30% |
Hours to allocate | 8 | 8 | 8 | 8 | 4 | 0 | 0 | |||
| Daily Cost | 108 | 108 | 108 | 108 | 54 | 0 | 0 | ||||
| Accrued Cost | 108 | 216 | 324 | 432 | 486 | 486 | 486 | 486 | |||
| Costing for an allocation of 3 days |
Hours to allocate | 4.4 | 4.4 | 4.4 | 4.4 | 4 | 0 | 0 | |||
| Daily Cost | 198 | 198 | 198 | 198 | 180 | 0 | 0 | ||||
| Accrued Cost | 198 | 396 | 594 | 793 | 972 | 972 | 972 | 972 |
If we allocate a certain number of hours of the resource to the task then ProjeX finds the number of available work hours for the task/resource combination. For our example below we can only work a maximum of 4 hours on Friday (so with an hourly rate of $45 we accrue 4 * $45 = $180) which leaves us with 26 hours (because we are only allocating 30 hours in total) to split between the remaining 4 days. This gives us 6.5 hours a day so we accrue 6.5 * 45 = $292.5 for each of those days.
If we have allocated a percentage of the resource then we can calculate the cost of the resource per hour as 30% of $45 = $13.5. For Friday we can only work 4 hours so that gives us $54 and we can work 8 hours for the 4 other days giving us $108 each.
If we allocate a certain number of days of the resource to the task then we need to calculate how many hours that number of days represents. To do this we calculate the average number of work hours available and multiple that by the number of days we want to allocate. In the example above we have 36 hours over 5 days so the average number of hours a day is 36 / 5 = 7.2 giving us 21.6 hours to allocate. For Friday we can only work 4 hours so that leaves us 17.6 hours. Over the 4 days that is 4.4 hours a day @ $45/hour giving us $198.
We can also define the cost of the resource per day, for the example below lets say the cost of the resource is $345 a day.
| Mon | Tue | Wed | Thur | Fri | Sat | Sun | Total hours |
Total Cost |
|||
| Res. Hours | 8 | 8 | 8 | 8 | 4 | 4 | 0 | 40 | |||
| Task Hours | 10 | 10 | 10 | 10 | 10 | 0 | 0 | ||||
| Available Hours |
8 | 8 | 8 | 8 | 4 | 0 | 0 | 36 | |||
| Costing for an allocation of 30 hours |
Hours to allocate | 6.5 | 6.5 | 6.5 | 6.5 | 4 | 0 | 0 | 36 | ||
| Daily Cost | 336.375 | 336.375 | 336.375 | 336.375 | 207 | 0 | 0 | ||||
| Accrued Cost | 336.375 | 672.75 | 1009.125 | 1345.5 | 1552.5 | 1552.5 | 1552.5 | 1552.5 | |||
| Costing for an allocation of 30% |
Hours to allocate | 8 | 8 | 8 | 8 | 4 | 0 | 0 | |||
| Daily Cost | 124.2 | 124.2 | 124.2 | 124.2 | 62.1 | 0 | 0 | ||||
| Accrued Cost | 124.2 | 248.4 | 372.6 | 496.8 | 558.9 | 558.9 | 558.9 | 558.9 | |||
| Costing for an allocation of 3 days |
Hours to allocate | 4.4 | 4.4 | 4.4 | 4.4 | 4 | 0 | 0 | |||
| Daily Cost | 227.7 | 227.7 | 227.7 | 227.7 | 207 | 0 | 0 | ||||
| Accrued Cost | 227.7 | 455.4 | 683.1 | 910.8 | 1117.8 | 1117.8 | 1117.8 | 1117.8 |
The cost calculations within ProjeX are based on hours available (for resource and task) so if we define the cost per day (or week, month or year) we need to calculate the average number of hours in a day so we can get the cost per hour. The average number of resource hours a day is the total resource hours available / the number of days. In the case the average number of resource hours a day is 40 / 6 = 6.67, we have a daily cost of $345 so the hourly resource cost is 345 / 6.67 = $51.75 per hour.
If we allocate a certain number of hours of the resource to the task then ProjeX finds the number of available work hours for each day using the same approach as the hourly example above.
If we have allocated a percentage of the resource then we can calculate the cost of the resource per hour as 30% of $51.75 = $15.525. For Friday we can only work 4 hours so that gives us $62.1 and we can work 8 hours for the 4 other days giving us $124.2 each.
If we allocate a certain number of days of the resource to the task then as before we need to calculate how many hours this represents. With 36 hours over 5 days we have an average of 7.2hours a day giving us a total of 21.6hours (for 3 days). We can only work 4 hours on Friday so that leaves us with 17.6hours for the other 4 days (ie. 4.4 hours a day).
The approach used when costs are defined per week, per month and per year are exactly the same as the per day but the cost supplied by the user is divided by 7, 28 and 365 respectively prior to calculating the hourly cost.
The final way of defining the cost is as a total cost for the resource, eg. we know that to hire a resource will cost a flat fee of $9,000.
| Mon | Tue | Wed | Thur | Fri | Sat | Sun | Total hours |
Total Cost |
|||
| Res. Hours | 8 | 8 | 8 | 8 | 4 | 4 | 0 | 40 | |||
| Task Hours | 10 | 10 | 10 | 10 | 10 | 0 | 0 | ||||
| Available Hours |
8 | 8 | 8 | 8 | 4 | 0 | 0 | 36 | |||
| Costing for an allocation of 30 hours |
Hours to allocate | 6.5 | 6.5 | 6.5 | 6.5 | 4 | 0 | 0 | 36 | ||
| Daily Cost | 1462.5 | 1462.5 | 1462.5 | 1462.5 | 900 | 0 | 0 | ||||
| Accrued Cost | 1462.5 | 2925 | 4387.5 | 5850 | 6750 | 6750 | 6750 | 6750 | |||
| Costing for an allocation of 30% |
Hours to allocate | 8 | 8 | 8 | 8 | 4 | 0 | 0 | |||
| Daily Cost | 600 | 600 | 600 | 600 | 300 | 0 | 0 | ||||
| Accrued Cost | 600 | 1200 | 1800 | 2400 | 2700 | 2700 | 2700 | 2700 | |||
| Costing for an allocation of 3 days |
Hours to allocate | 4.4 | 4.4 | 4.4 | 4.4 | 4 | 0 | 0 | |||
| Daily Cost | 990 | 990 | 990 | 990 | 900 | 0 | 0 | ||||
| Accrued Cost | 990 | 1980 | 2970 | 3960 | 4860 | 4860 | 4860 | 4860 |
Again if we have allocated a number of hours of the resource then ProjeX finds the number of available work hours for the task/resource combination, calculates the hourly cost of the resource from the total cost of the resource divided by the number of resource hours available. In the case above we have a total cost of $9000 and 40 available resource hours so the hourly cost is 9000 / 40 = $225 per hour. We have a total of 30 hours to accrue but can only accrue 4 hours on Friday so that leaves 26 hours to be accrued over the other 4 days - ie. $1462.5 (and $900 for Friday).
If we have allocated a percentage of the resource, ProjeX finds the actual number of available work hours (in this example 36), finds the value of the resource to allocate (30% of $9000 = $2700) which gives an hourly rate of 2700 / 36 = $75. For each day this is multiplied by the number of work hours.
If we have allocated a number of days of the resource, ProjeX again finds the average number of hours in a day for the resource and multiplies that by the number of days to get the total hours to allocate and then uses the same approach as above to get the costs.