A comprehensive guide to project management formulas, metrics, and terms used across Rockwall.
Showing 24 of 24 definitions
A scheduling technique that identifies the longest sequence of dependent tasks, determining the minimum project duration. Tasks on the critical path have zero float.
Formula
Float = Late Start − Early Start (or) Late Finish − Early Finish
Example
If Task A (5 days) → Task B (3 days) → Task C (4 days), the critical path is 12 days and none of these tasks can be delayed without extending the project.
The amount of time a task can be delayed without delaying the project end date. Tasks with zero float are on the critical path.
Formula
Total Float = Late Start − Early Start = Late Finish − Early Finish
Example
If a task has Early Start = Day 5, Late Start = Day 9, then Total Float = 9 − 5 = 4 days.
The amount of time a task can be delayed without delaying the Early Start of its successor tasks.
Formula
Free Float = Early Start of Successor − Early Finish of Current Task
Example
Task A finishes Day 10, successor Task B has Early Start Day 14: Free Float = 14 − 10 = 4 days.
Measures schedule performance by comparing the value of work performed versus the value of work planned. Negative means behind schedule.
Formula
SV = EV − PV
Example
EV = $40,000 (work done), PV = $50,000 (work planned): SV = $40,000 − $50,000 = −$10,000 (behind schedule).
A ratio measuring scheduling efficiency. SPI < 1 means behind schedule; SPI > 1 means ahead of schedule; SPI = 1 is on track.
Formula
SPI = EV ÷ PV
Example
EV = $40,000, PV = $50,000: SPI = 40,000 ÷ 50,000 = 0.80 (working at 80% of planned speed).
The budgeted cost of the work actually performed. It represents the "value" of the work done expressed in terms of the approved budget.
Formula
EV = % Complete × Budget at Completion (BAC)
Example
Project BAC = $100,000, 40% complete: EV = 0.40 × $100,000 = $40,000.
The authorized budget assigned to scheduled work. Also called Budgeted Cost of Work Scheduled (BCWS). It represents what should have been done by now.
Formula
PV = Planned % Complete × BAC
Example
Project BAC = $100,000, should be 50% done: PV = 0.50 × $100,000 = $50,000.
The actual cost incurred for work performed on a project during a specific time period. Also called Actual Cost of Work Performed (ACWP).
Formula
AC = Sum of all actual costs incurred to date
Example
If you've spent $48,000 on labor, materials, and overhead to complete 40% of work: AC = $48,000.
Measures cost performance by comparing the value of work performed to the actual cost. Negative means over budget.
Formula
CV = EV − AC
Example
EV = $40,000 (work done), AC = $48,000 (spent): CV = $40,000 − $48,000 = −$8,000 (over budget).
A ratio measuring cost efficiency. CPI < 1 means over budget; CPI > 1 means under budget; CPI = 1 is on budget.
Formula
CPI = EV ÷ AC
Example
EV = $40,000, AC = $48,000: CPI = 40,000 ÷ 48,000 = 0.83 (getting $0.83 of value per $1 spent).
Forecasts the expected total cost of the project at completion, based on current performance trends.
Formula
EAC = BAC ÷ CPI (or) EAC = AC + (BAC − EV)
Example
BAC = $100,000, CPI = 0.83: EAC = $100,000 ÷ 0.83 = $120,482 (projected final cost).
The expected cost to finish all remaining project work from the current point in time.
Formula
ETC = EAC − AC
Example
EAC = $120,482, AC = $48,000: ETC = $120,482 − $48,000 = $72,482 remaining to spend.
The difference between the original budget and the forecasted final cost. Negative means the project will exceed budget.
Formula
VAC = BAC − EAC
Example
BAC = $100,000, EAC = $120,482: VAC = $100,000 − $120,482 = −$20,482 (projected overrun).
The cost performance required to complete the remaining work within the budget. TCPI > 1 means future work must be more cost-efficient.
Formula
TCPI = (BAC − EV) ÷ (BAC − AC)
Example
BAC = $100,000, EV = $40,000, AC = $48,000: TCPI = (100,000 − 40,000) ÷ (100,000 − 48,000) = 60,000 ÷ 52,000 = 1.15.
The proportion of the total work that has been accomplished at a given point in time, expressed as a percentage.
Formula
% Complete = (Work Completed ÷ Total Work) × 100
Example
30 of 100 tasks done: % Complete = (30 ÷ 100) × 100 = 30%.
Red-Amber-Green status indicator showing project health at a glance. Green = on track, Amber = at risk, Red = off track.
Formula
RAG = f(SPI, CPI, schedule variance, risk level)
Example
SPI = 0.75 and CPI = 0.80 → Red status. SPI = 0.95 and CPI = 0.98 → Green status.
The percentage of a resource's available capacity that is being used on project tasks.
Formula
Utilization % = (Assigned Hours ÷ Available Hours) × 100
Example
Resource works 8 hrs/day, assigned 6 hrs/day: Utilization = (6 ÷ 8) × 100 = 75%.
The total cost of a resource's work based on their hourly rate and the number of hours worked on project tasks.
Formula
Labor Cost = Hours Worked × Hourly Rate
Example
Developer works 120 hrs at $85/hr: Labor Cost = 120 × $85 = $10,200.
Lag is a delay between two linked tasks. Lead (negative lag) allows a successor to start before its predecessor finishes.
Formula
Adjusted Start = Predecessor Date + Lag (negative lag = lead)
Example
Task B starts 3 days after Task A finishes (Lag = +3). Or Task B starts 2 days before Task A finishes (Lead = −2).
A hierarchical decomposition of the total scope of work into smaller, manageable components. Each level provides greater detail.
Formula
WBS Number = Parent.Child (e.g. 1.2.3 = Section 1 → Subsection 2 → Task 3)
Example
1.0 Project, 1.1 Planning, 1.1.1 Requirements, 1.1.2 Design, 1.2 Development, 1.2.1 Frontend…
A quantitative assessment of a risk's overall severity, combining its probability of occurrence with its potential impact.
Formula
Risk Score = Probability × Impact (on a scale of 1–5 or 1–10)
Example
Risk has 60% probability (3/5) and High impact (4/5): Risk Score = 3 × 4 = 12 (High).
The total approved budget for the project. It is the sum of all budgeted costs for all project work.
Formula
BAC = Sum of all approved budgets for the project scope
Example
Phase 1: $30,000 + Phase 2: $50,000 + Phase 3: $20,000 = BAC $100,000.
A significant point or event in the project, typically marking completion of a major deliverable or phase. Milestones have zero duration.
Formula
Duration = 0 (a point in time, not a span)
Example
Milestones include: "Design Approved", "Beta Launch", "User Acceptance Testing Complete".
A technique for constructing a schedule network diagram using nodes (boxes) to represent activities and arrows to show dependencies.
Formula
FS: Successor starts after predecessor finishes SS: Successor starts when predecessor starts FF: Successor finishes when predecessor finishes SF: Successor finishes before predecessor starts
Example
Task A (FS) → Task B means Task B cannot start until Task A is fully complete.