Count the IAM policy statements a compartment design implies, check the limits and price the review effort.
The policy surface multiplies out: every compartment needs a statement for each group and each resource family it touches, so a modest design produces hundreds of statements. Because a statement written at a parent compartment is inherited by every compartment beneath it, moving grants up the tree is what actually reduces the count. IAM itself carries no charge, but the review burden is real and it scales with statement count — that is the cost this model prices, and it is the reason a flat compartment design with inherited policies beats a deep one with repeated grants. The six-level nesting limit is also a hard constraint you cannot design around later.
OCI IAM Policy
statements = compartments × groups per compartment × resource families per group; policy documents = ceil(statements ÷ statements per document).
statements = compartments × groups per compartment × resource families per group; policy documents = ceil(statements ÷ statements per document). The policy surface multiplies out: every compartment needs a statement for each group and each resource family it touches, so a modest design produces hundreds of statements. Because a statement written at a parent compartment is inherited by every compartment beneath it, moving grants up the tree is what actually reduces the count.
IAM itself carries no charge, but the review burden is real and it scales with statement count — that is the cost this model prices, and it is the reason a flat compartment design with inherited policies beats a deep one with repeated grants. The six-level nesting limit is also a hard constraint you cannot design around later.
This calculator takes 8 inputs: Compartments needing policies, Groups granted access per compartment, Resource families per group, Deepest compartment nesting, Statements per policy document, Review time per statement, Access reviews per year, Loaded engineer rate. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.