HKSM

Quantified effort, resource, and cost assumptions for each work package in the WBS. It specifies quantities, rates, and key assumptions used to calculate costs. It enables bottom-up estimating and supports a defensible project budget.

Key Points

• A structured estimate at the work package level, aligned to WBS IDs and the WBS dictionary.
• Includes quantities, resource hours, unit rates, vendor quotes, overheads (if applied), contingency, and a clear basis of estimate.
• Captures assumptions, constraints, estimating method, range (e.g., ±10–25%), and confidence level.
• Built collaboratively by work package owners, SMEs, and cost estimators using historical data and market rates.
• Feeds bottom-up rollups to control accounts, total project cost, and the cost baseline.
• Lives as a document or spreadsheet/model in the estimating repository with version control.

Purpose

Provide traceable, defensible inputs to calculate work package costs and aggregate them into the project estimate. Align stakeholders on what is included, excluded, and the confidence level of the numbers.

Support funding decisions, procurement planning, cash flow phasing, and reserve determination by documenting the reasoning behind the numbers.

How to Create

• Gather inputs: approved WBS and dictionary, scope statements, resource calendars, rate cards, historical data, and vendor quotations.
• Select estimating techniques per work package (analogous, parametric, bottom-up, three-point) based on data quality and risk.
• Develop quantity takeoffs and effort models for labor, materials, equipment, and services.
• Compute direct costs by multiplying quantities or hours by unit rates; add applicable indirects or overheads per organizational policy.
• Assess risks and add work-package-level contingency aligned to identified threats and opportunities.
• Document the basis of estimate: methods used, data sources, key assumptions, exclusions, range, and confidence level.
• Peer review with SMEs, reconcile to constraints, and adjust where necessary; record version, date, and preparer.
• Store in the central repository, linking every line to a WBS ID and control account.

How to Use

• Roll up work package estimates to control accounts and the overall project estimate for budget setting.
• Phase costs over time to build cash flow forecasts and funding requests.
• Inform make-or-buy decisions and prepare procurement packages with realistic cost expectations.
• Calibrate contingency and management reserves through aggregation and risk analysis.
• Baseline approved figures into the cost baseline; use as the reference for variance analysis and forecasts.
• Perform impact assessments for change requests by updating affected work package estimates.
• Compare to actuals to improve future estimating accuracy and update organizational knowledge bases.

Ownership & Update Cadence

• Primary owner: Project manager or cost engineer; contributors: work package leads, finance, and procurement.
• Update during planning iterations and whenever scope, rates, or vendor inputs change; apply change control after baselining.
• Review at phase gates and on a defined cycle (e.g., monthly or quarterly for long projects) with strict version control.

Example

Data Migration Project, WP 3.2 “Extract Legacy Data” (WBS ID 1.2.3): 120 labor hours at $85/hour = $10,200. Temporary tool license = $1,200. Secure staging storage = $300. Contingency 10% for data anomalies = $1,170. Total WP estimate = $12,870. Basis: bottom-up labor model using historical extraction rates; vendor quote for tool; assumption that legacy DB access windows are four hours nightly.

Rolled up with related WPs under the Data Migration control account to establish the control account estimate and feed the project cost baseline.

PMP Example Question

During Estimate Costs, a project manager needs the detailed quantities, unit rates, and assumptions at the lowest planning level to build a defensible budget. Which artifact provides this information?

1. Work package estimation.
2. Cost baseline.
3. Funding limit reconciliation.
4. Activity list.

Correct Answer: A — Work package estimation.

Explanation: Work package estimation contains the detailed, bottom-up numbers and assumptions needed to compute costs. The cost baseline and funding limits are derived later, and the activity list does not include cost details.