The ratio of the earned value (EV), which is sometimes referred to as the budgeted cost of work performed (BCWP), to the planned value (PV), which is sometimes referred to as the budgeted cost of work scheduled (BCWS). SPI is often used to estimate the project completion date. The SPI value is calculated as follows: SPI = EV/PV. If the resulting SPI value is less than 1.0, that indicates that less work was completed on the project than was planned. If the SPI value is 1.0 or greater, that indicates that more work was completed than was planned.