Top-down and bottom-up are two approaches to IT capacity planning that start from opposite ends and try to meet in the middle. Organizations that only run one of them typically produce a capacity plan that is either disconnected from actual project demand or based on estimates that are systematically optimistic.
The value comes from running both and reconciling the gap. The gap itself is the most useful output of the exercise.
Top-down capacity planning
In top-down planning, leadership sets capacity allocations first. The CIO or portfolio manager looks at the total IT resource base and divides it into strategic categories based on organizational priorities and budget targets.
A typical top-down allocation might look like:
- 40% of IT capacity allocated to new strategic initiatives
- 35% to operational maintenance and production support
- 15% to infrastructure and platform work
- 10% reserved for unplanned demand and urgent requests
These percentages translate to FTE allocations. If the IT team has 50 FTEs, 20 go to strategic initiatives, 17.5 to operations, and so on. The governance body then approves new projects up to the available FTE allocation in each category.
Top-down planning is fast, aligns directly with budget cycles, and gives finance and executive leadership a clear picture of how IT capacity is being invested. You do not need detailed project estimates to run it. That speed is also its primary weakness.
Why top-down alone fails
Top-down allocations are based on intentions, not commitments. They assume the team actually has the capacity and skills to fill each allocation bucket, and that operational demand will stay within its allocated percentage.
Both assumptions routinely fail. Operational demand almost always expands. Production issues, security patches, urgent enhancements, and the long tail of small requests that don't qualify as projects collectively consume more than their allocated percentage in most organizations. An allocation of 35% to operations often becomes 50 to 55% in practice.
Top-down allocation also does not account for skill constraints. Saying 40% of capacity goes to strategic initiatives does not help when the strategic initiatives all require data engineering skills and the data engineering team is already fully committed to carryover work from last year.
Bottom-up capacity planning
In bottom-up planning, project managers and team leads estimate the hours or FTEs required for each specific piece of work. Those estimates roll up to produce a total demand figure by skill area and by period.
Bottom-up planning is grounded in actual work. It produces demand numbers that reflect specific projects with specific resource requirements, broken out by the skill types those projects need. It catches the skill-level constraints that top-down misses entirely.
Why bottom-up alone fails
Bottom-up estimates are optimistic by construction. Project teams estimate the work they can see, not the work that will emerge. Integration complexity, rework cycles, testing delays, and the coordination overhead of dependencies between projects are consistently underestimated at the individual project level.
Additionally, bottom-up estimates aggregate without a constraint. If project teams total up their FTE demand without reference to what the organization has decided is available for each category, the result is a demand figure that may be double the actual capacity. The estimates are not wrong in isolation. They are just unconstrained by reality.
The reconciliation: where both become useful
Running both approaches in parallel and comparing the results is what makes each one useful. The steps:
Step 1: Run the top-down allocation. Set expected capacity percentages by strategic category. Express them in FTEs per skill area per quarter.
Step 2: Run the bottom-up estimate. Sum FTE demand from all approved and proposed projects, broken out by skill area and by quarter.
Step 3: Compare by category and by skill area. Where bottom-up demand in a category exceeds the top-down allocation, you have a gap that requires a decision.
| Category | Top-down allocation (FTE) | Bottom-up demand (FTE) | Gap |
|---|---|---|---|
| Strategic initiatives | 20.0 | 28.5 | +8.5 |
| Operations and maintenance | 17.5 | 24.0 | +6.5 |
| Infrastructure and platform | 7.5 | 6.2 | -1.3 |
| Reserve | 5.0 | 5.0 | 0.0 |
In this example, both strategic initiatives and operations are materially over-allocated. The governance body now has a concrete picture to work from. Either the top-down allocations for those categories need to increase (which requires reducing other areas or adding capacity), or the bottom-up demand needs to come down by deferring projects or constraining the operational scope.
Step 4: Reconcile. Adjust one or both sides until they align. Increase the top-down allocation by shifting capacity between categories, or reduce bottom-up demand by deferring projects, cutting scope, or adding resources. The output is a capacity plan both sides have agreed to.
The reconciliation meeting
The reconciliation is not an analytical exercise. It is a decision meeting. Until the two sides have been compared and adjusted, the numbers are aspirational. The reconciliation meeting is the point at which the capacity plan becomes a commitment the organization is accountable to.
The meeting should include IT leadership, the PMO, and finance. The output: a documented capacity plan by category and by skill area, with the list of projects that were deferred or descoped to make the plan feasible.
Cadence
Most organizations reconcile annually during the planning cycle, with quarterly check-ins to catch drift. The quarterly check is not a full re-plan. It compares current actuals to the plan and flags categories where the assumptions have materially diverged from reality.
When a key resource leaves, a major project scope expands, or a new strategic priority arrives, an off-cycle reconciliation is warranted. Carrying forward a plan built on assumptions that no longer hold produces a fictional capacity picture within weeks.
For how FTE demand is estimated from the bottom up, see the article on FTE planning for IT projects. For a worked example of the gap analysis that the reconciliation relies on, see capacity vs demand gap analysis in IT portfolio management.
Frequently Asked Questions
What is top-down capacity planning?
Top-down capacity planning is the approach where leadership sets capacity allocations first based on strategic priorities and budget targets. The CIO decides what percentage of IT capacity goes to strategic initiatives, operations, and infrastructure. Those percentages translate to FTE allocations that constrain how much project work can be approved in each category.
What is bottom-up capacity planning?
Bottom-up capacity planning is the approach where project managers estimate the hours and FTEs required for each specific piece of work, and those estimates roll up to reveal total portfolio demand. The aggregate figure is compared to available capacity to identify gaps by skill area.
Why does top-down capacity planning alone fail?
Top-down allocations do not account for specific skill constraints, existing carryover project commitments, or the reality that operational work routinely expands beyond its allocated percentage. An organization that plans 35% for operations often finds operations consuming 50 to 55% of actual capacity before any new strategic projects start.
How do you reconcile top-down and bottom-up capacity plans?
Run both in parallel. Set top-down allocations by category. Sum bottom-up FTE demand from all projects by the same categories. Compare. Where bottom-up demand exceeds the top-down allocation, the governance body must increase the allocation, reduce demand by deferring projects, or accept that the target will not be met. The reconciliation meeting is where the plan becomes a real commitment.