EV, SPI and CPI: the earned value calculations that matter
Earned value takes three numbers (planned value, earned value and actual cost) and turns them into an honest read on whether a project is ahead or behind, and whether it's spending more than the work is worth.
The formulas aren't the hard part. Trusting the inputs is.
SV = EV − PV. CV = EV − AC. SPI = EV / PV. CPI = EV / AC. Earned value is only as good as your measure of physical progress, and on most projects that measure comes from the same site records nobody has time to review properly.
SPI below 1.0 means you're behind the planned programme
CPI below 1.0 means the work is costing more than it was budgeted at
Both drifting together usually means the baseline stopped reflecting reality some time ago
The interactive calculator now lives on QS Tools
QS Tools is our free sister platform, built by the founders of Gather. The earned value calculator runs inside the QS Tools app, so you will need a free QS Tools account to use it.
Prefer to stay in a spreadsheet? The EVM Excel template does the same calculations offline, with no account and no email.
EAC, ETC and TCPITurning today's performance into a defensible final cost forecast.
A full worked exampleOne £12.4M project tracked month by month from green to red and back.
EVM glossary100 earned value terms in plain English.
Gather is the AI site diary and commercial record platform this calculation sits inside. It reads your site diaries against your NEC4 contract and flags the compensation events a manual review misses. If that's the problem you're actually solving, book a demo.
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