Schedule Performance Index (SPI) Calculator
Measure how much of the planned work the project has actually completed.
What this calculator does
Earned value divided by planned value; the schedule variance is the difference between them. Both values come from the project's measurement baseline.
Inputs and what they mean
- Currency
- — Amounts are shown in the currency you pick. No exchange rate is applied..
- Earned value (EV)
- — number value.
- Planned value (PV)
- — number value.
How to use it
- Enter your own figures — the calculator never fills in a rate, price or benchmark for you.
- Press Calculate to see the result.
- Read the formula, variables, assumptions and source below the result before you rely on it.
Formula
SPI = EV ÷ PV; SV = EV − PV
Worked example
$80,000 earned against $100,000 planned
An SPI of 0.8 — one fifth of the planned work is outstanding.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
Results depend entirely on the figures you enter and are rounded for display. They are for general information and education, not professional advice.
Reference: PMI — Earned value management — PMI practice guidance
Last reviewed:
Common questions
Formula, source and verification
Earned value divided by planned value; the schedule variance is the difference between them.
The question it answers: Have we completed as much work as we planned to by now?
The formula
SPI = EV ÷ PV; SV = EV − PV
- EV — Earned value
- (currency). Budgeted cost of completed work.
- PV — Planned value
- (currency). Budgeted cost of work scheduled to date.
Units: Currency in; dimensionless index and currency variance out.
What kind of calculation this is
Deterministic formula. The same inputs always give the same answer. The maths is fixed and does not depend on judgement.
Method
Both values come from the project's measurement baseline.
Assumptions built into the result
- Operational: Earned value and planned value are measured to the same date.
Figures this calculator will never guess for you
- No assumed schedule buffer or productivity factor.
Limitations
- Near the end of a project SPI tends towards 1 even when the project is late; use schedule analysis as well.
Source and version
- Standard or reference
- Earned value management — PMI (PMI earned value management practice guidance: SPI and SV definitions.)
- Published source
- PMI — Practice guidance
- Formula version
- Version 1
- Verification
- Reviewed against the cited source on
- How much weight the source carries
- Standards or government
- Applies to
- Currency
- Amounts stay in the currency you choose; no exchange rate is applied.
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