Schedule performance index (SPI)
The schedule performance index (SPI) is a measure of how close the project is to being completed compared to the schedule.
As a ratio it is calculated by dividing the budgeted cost of work performed, or earned value, by the planned value.
For example:
- A project has a budgeted cost of £120,000.
- According to the schedule, 15% of the project should have been completed after one month (planned value). That is £120,000 x 15 / 100 = £18,000.
- But after a month, only 12% of the project has actually been completed (earned value). That is £120,000 x 12 / 100 = £14,400.
SPI = EV / PV = 14,400 / 18,000 = 0.8
This means that for every estimated hour of work, the project team is only completing 0.8 hours (just over 45 minutes).
If the ratio has a value higher than 1 this indicates the project is progressing well against the schedule. If the SPI is 1, then the project is progressing exactly as planned. If the SPI is less than 1 then the project is running behind schedule.
[edit] Related articles on Designing Buildings Wiki
- Activity schedule.
- Cost performance index (CPI).
- Benchmarking.
- Design programme.
- Earned value.
- Fast-track construction.
- Key performance indicators KPI.
- Lead time.
- Programme for building design and construction.
- Project crashing.
- Scheduling construction activities.
- Time management of construction projects.
[edit] External references
Featured articles and news
Future Homes Standard Essentials launched
Future Homes Hub launches new campaign to help the homebuilding sector prepare for the implementation of new building standards.
Building Safety recap February, 2026
Our regular run-down of key building safety related events of the month.
Planning reform: draft NPPF and industry responses.
Last chance to comment on proposed changes to the NPPF.
A Regency palace of colour and sensation. Book review.
Delayed, derailed and devalued
How the UK’s planning crisis is undermining British manufacturing.
How much does it cost to build a house?
A brief run down of key considerations from a London based practice.
The need for a National construction careers campaign
Highlighted by CIOB to cut unemployment, reduce skills gap and deliver on housing and infrastructure ambitions.
AI-Driven automation; reducing time, enhancing compliance
Sustainability; not just compliance but rethinking design, material selection, and the supply chains to support them.
Climate Resilience and Adaptation In the Built Environment
New CIOB Technical Information Sheet by Colin Booth, Professor of Smart and Sustainable Infrastructure.
Turning Enquiries into Profitable Construction Projects
Founder of Develop Coaching and author of Building Your Future; Greg Wilkes shares his insights.
IHBC Signpost: Poetry from concrete
Scotland’s fascinating historic concrete and brutalist architecture with the Engine Shed.
Demonstrating that apprenticeships work for business, people and Scotland’s economy.
Scottish parents prioritise construction and apprenticeships
CIOB data released for Scottish Apprenticeship Week shows construction as top potential career path.
From a Green to a White Paper and the proposal of a General Safety Requirement for construction products.
Creativity, conservation and craft at Barley Studio. Book review.
The challenge as PFI agreements come to an end
How construction deals with inherited assets built under long-term contracts.
Skills plan for engineering and building services
Comprehensive industry report highlights persistent skills challenges across the sector.
Choosing the right design team for a D&B Contract
An architect explains the nature and needs of working within this common procurement route.
Statement from the Interim Chief Construction Advisor
Thouria Istephan; Architect and inquiry panel member outlines ongoing work, priorities and next steps.
Comments
Its just 12/15 no need to multiply the percentage by the budget.
Indeed.