Percentages used in search to compare availability are of two types, depending on the context of your resource search:
The Availability match percentage is the percentage of time a resource is available to work for a specific project requirement. It is calculated as [resource's (capacity hours - assigned hours)] /requirement hours*100.
The Availability percentage measures the percentage of time the resource is available to work, simply based on their capacity to work. It is calculated as [resource's (capacity hours - assigned hours/capacity hours)]*100.
Both measure the percentage of the availability of the resource to work. The availability match percentage is to fill a specific requirement, while the availability percentage just measures the availability of the resource and is independent of filling a specific requirement.
Both the availability percentages above have two views, which are displayed in the resources search results.
Definite availability is based on the confirmed assignments. Therefore
Definite availability match percentage is [resource's (capacity hours - confirmed assignment hours)] /requirement hrs)*100]
Definite availability percentage is [resource's (capacity hours - confirmed assignment hours/capacity hours)]*100
Potential availability is based on the confirmed and provisional assignments. Therefore
Potential availability match percentage is [resource's (capacity hours - confirmed assignment hours - potential assignment hours)] /requirement hrs)*100]
Potential percentage is [resource's (capacity hours-confirmed assignment hours - potential assignment hours/capacity hours)]*100.
For example, a resource who has a weekly capacity of 40 hours is confirmed on an assignment for 20 of those hours. If you have a requirement for 20 hours, the resource will show to have a definite availability match percentage of 100% [resource's (capacity hours - confirmed assignment hours)] /requirement hrs)*100 as he is available for the entire required hours. If you simply search for this resource outside the context of filling a requirement, his definite availability percentage is 50% [resource's (capacity hours-confirmed assignment hours/capacity hours)]*100 and he has 50% of his capacity already committed.
If this resource also has a provisional assignment of 10 hours, his potential availability match percentage is 50% [(40 capacity hours-20 confirmed assignment hours - 10 potential assignment hours/20 requirement hours*100], and his availability percentage is 25% [(40 capacity hours - 20 confirmed assignment hours - 10 potential assignment hours)/ 40 capacity hours*100].
The availability percentage of a resource is considered from the current system date and does not reflect any past dates. For example, you have a requirement that spans four weeks with the start date that began last week. If a resource is found to have the next three weeks 100% available, then that resource is considered as having a 100% available match without any regard to the availability of the resource for the first week of the requirement. A resource search will never return any results when the requirement is completely in the past (when the end date of the requirement is prior to the current date.) In order for a resource to qualify for the search results, the resource must have availability for at least a portion of the assignment duration.
You can view the availability of a resource on the timeline on the Resource Details page.