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
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Heritage staff wellbeing at work survey.
A five minute introduction.
50th Golden anniversary ECA Edmundson apprentice award
Showcasing the very best electrotechnical and engineering services for half a century.
Welsh government consults on HRBs and reg changes
Seeking feedback on a new regulatory regime and a broad range of issues.
CIOB Client Guide (2nd edition) March 2025
Free download covering statutory dutyholder roles under the Building Safety Act and much more.
Minister quizzed, as responsibility transfers to MHCLG and BSR publishes new building control guidance.
UK environmental regulations reform 2025
Amid wider new approaches to ensure regulators and regulation support growth.
BSRIA Statutory Compliance Inspection Checklist
BG80/2025 now significantly updated to include requirements related to important changes in legislation.
Comments
Its just 12/15 no need to multiply the percentage by the budget.
Indeed.