Earned value metrics without the pain: CPI, EAC, and friends

Earned value management has a reputation problem. It sounds like something only defence contractors with dedicated cost engineers can do. In reality, four numbers cover most of what a programme manager needs, and all four can be calculated automatically from data you already track: planned cost, actual cost, and percentage complete.

Earned Value (EV) is percentage complete multiplied by planned cost. If a $100,000 task is 40% done, you have earned $40,000 of value. Compare that with what you actually spent and you get the Cost Performance Index: CPI equals EV divided by actual cost. A CPI of 1.0 means you are getting a dollar of value for every dollar spent. Above 1.0 you are under budget. Below 0.8 you are in trouble, and the trouble compounds.

The forward-looking metrics matter more than the backward-looking ones. Estimate at Completion (EAC) projects your final cost if current efficiency continues: actual cost plus the remaining work divided by CPI. Estimate to Complete (ETC) is what is left to spend. Variance at Completion (VAC) is your original budget minus EAC, which is the number your finance director actually cares about, because a negative VAC means the programme will finish over budget.

The trap most teams fall into is calculating these quarterly in a spreadsheet ritual. By the time a quarterly CPI shows 0.85, the money is gone. Calculated continuously per task and rolled up by delivery group, the same metrics become an early warning system: a single workstream whose CPI drifts from 1.0 to 0.9 over three weeks is visible long before it drags the programme number down.

Start simple. Track planned cost and actual cost per task, keep percentage complete honest, and let your tooling do the arithmetic. Set a colour-coded threshold, green at or above 1.0, amber between 0.8 and 1.0, red below 0.8, and review anything amber weekly. That single habit catches most budget problems while they are still cheap to fix.