Azure RBAC Calculator
Track Azure role assignments against the 4000-per-subscription limit and custom roles against 500 per tenant.
About Azure RBAC Calculator
Azure counts each role assignment object against a per-subscription limit, and that limit is reached surprisingly often because assignments are made at resource-group and resource scope as well as subscription scope. Targeting a group instead of a user collapses many assignments into one without changing effective access. When a subscription hits 4000 assignments, new access requests simply fail, and the fix — re-modelling hundreds of user assignments onto groups — is a project rather than a ticket.
Formulas
Azure RBAC
utilisation = role assignments ÷ 4000 per subscription; a group assignment replaces one assignment per member, so savings = assignments × (members per group − 1).
- 500
- Custom role definitions per tenant
- 4000
- Role assignments allowed per Azure subscription
- members
- Users behind a single group assignment
Tenant-wide assignment footprint
assignments across the tenant = assignments per subscription × subscriptions.
- subscriptions
- Each carries its own independent 4000-assignment budget
Worked example
With the default values below, Azure RBAC Calculator returns Subscription Assignment Utilisation of 65.0%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Role assignments in the subscriptionaccepts 0–6,000 assignments
- 2,600 assignments
- Custom roles in the tenantaccepts 0–1,000 roles
- 180 roles
- Subscriptions in the tenantaccepts 1–1,000 subscriptions
- 6 subscriptions
- Assignments target groups rather than users
- Yes
- Average members per groupaccepts 1–10,000 users
- 40 users
Results
- Subscription Assignment Utilisation
- 65.0%
- Assignments Remaining
- 1,400 of 4000
- Custom Roles vs 500 per Tenant
- 36.0%
- Assignments if Made per User
- 104,000
- Assignments Saved by Group Targeting
- 101,400
- Assignments Across All Subscriptions
- 15,600
- Assessment
- Within Azure RBAC limits
Step by step
- 1Values used
- 2Azure RBAC
- 3Tenant-wide assignment footprint
- 4Subscription Assignment Utilisation= 65.0
- 5Assignments Remaining= 1,400 of 4000
- 6Custom Roles vs 500 per Tenant= 36.0
- 7Assignments if Made per User= 104,000
- 8Assignments Saved by Group Targeting= 101,400
- 9Assignments Across All Subscriptions= 15,600
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Azure RBAC calculated?
utilisation = role assignments ÷ 4000 per subscription; a group assignment replaces one assignment per member, so savings = assignments × (members per group − 1). Azure counts each role assignment object against a per-subscription limit, and that limit is reached surprisingly often because assignments are made at resource-group and resource scope as well as subscription scope. Targeting a group instead of a user collapses many assignments into one without changing effective access.
Why does Azure RBAC matter?
When a subscription hits 4000 assignments, new access requests simply fail, and the fix — re-modelling hundreds of user assignments onto groups — is a project rather than a ticket.
What values do I need to enter?
This calculator takes 5 inputs: Role assignments in the subscription, Custom roles in the tenant, Subscriptions in the tenant, Assignments target groups rather than users, Average members per group. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
How do I stay under the Azure role assignment limit?
Assign roles to Microsoft Entra groups instead of individual users, prefer assignments at management-group or subscription scope over dozens of resource-scope assignments, remove assignments for deleted principals, and use Privileged Identity Management for eligible rather than permanent access so short-lived assignments do not accumulate.
Do inherited assignments count against the subscription limit?
No. An assignment created at management-group scope is counted against that management group, not against every subscription beneath it — which is exactly why moving broad access up the hierarchy is the fastest way to reclaim subscription headroom.
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