Actual cost to planning estimate: the report card on your planning's accuracy

The planner walks the job, counts the pipe sections, checks the rental catalogue, and logs a cost estimate of $3,170. The work order is approved, the job gets done, and when the final invoice lands it comes to $3,690.

That is sixteen per cent over estimate. Once in a while, it is simply bad luck. But if jobs run over consistently, and in the same direction, then either the planner's assumptions need revisiting or something in the execution is quietly adding cost that nobody is accounting for. This metric is how you tell the difference.

What it actually measures

Actual cost to planning estimate is the ratio of a job's final cost to the planner's original estimate, written as a percentage. A result of 100% means the job landed exactly on estimate; above 100% it cost more than planned, below 100% it came in under.

How to work it out

Actual cost to planning estimate (%) = (Actual cost ($) × 100) / Planned cost ($)

A pipe-replacement job was estimated at $3,170 and closed at $3,690, the overrun coming mostly from extra labour hours and a dearer manlift rental.

Actual cost to planning estimate = ($3,690 × 100) / $3,170 = 116.4%

The job ran 16.4% over, which sits just outside the window a mature planning function would aim for.

What good looks like

Best-in-class lands within roughly ten to fifteen per cent of the estimate. The cost version is usually held to the looser end of that, around fifteen per cent, with the labour-hours version kept tighter at ten, simply because materials prices are harder to pin down than time. The exact figure matters less than the discipline behind it: establish where you are, then tighten the acceptable window as your planning matures. A result that drifts far outside it, in either direction, signals either shaky estimating or an execution process that is not under control.

The single-job trap

This is the mistake that quietly poisons the metric, and it is worth stating plainly: a single job's cost can be off by half again, or double, and still be entirely normal. Estimates are not built to be right on any one job; they are built to be right across many, where the overruns and the underruns cancel out. Run the numbers over a whole week of work and the planner's estimates typically land within a few per cent of reality, even though the individual jobs scatter wildly. The unbreakable rule that follows is that you must never use this number to judge a planner, or a technician, on a single work order. Do that and you teach people to pad every estimate until it is meaningless. Read across the portfolio, it is one of the truest measures of whether your planning can be trusted; read job by job, it is just noise with a grudge.

Where it can mislead you

Actual cost to planning estimate is the report card for your planning function's financial accuracy, closing the loop between what was promised and what was spent. Read it as a portfolio, never as a verdict on one job, and it tells you something quietly vital: whether the plans your whole schedule rests on are numbers the business can actually believe.