The planned to reactive ratio, and what it does not tell you
It is the most quoted number in maintenance and the easiest to move without improving anything.
The share of maintenance effort that is planned rather than reactive is the industry's headline metric. Targets in the region of four fifths planned are widely cited, and departments are measured against them. For a product-side comparison related to balancing capacity, demand and productive time, see workforce optimization software before deciding which data the operation actually needs.
The underlying idea is sound: work anticipated is cheaper, safer and less disruptive than work discovered. The metric as usually implemented is considerably weaker than the idea.
It is trivially gameable
The ratio can be improved without touching the building. Add low-value planned tasks at high frequency and the planned count rises. Record several reactive jobs as one. Classify a routine inspection as planned work when it is really a walk round. For a wider operational and compliance reference, consult the Better Buildings O&M guide.
None of this makes the building more reliable. All of it moves the number, and where the number is a target, some of it will happen without anyone intending to game anything.
A ratio of job counts is dominated by whichever category contains the most small jobs. Measured in labour hours it is harder to move accidentally and closer to what you actually care about.
Not all reactive work is a failure of planning
Some assets are deliberately run to failure because that is the correct economic decision — low criticality, cheap, quick to replace, no consequential damage. Reactive work on those assets is the plan working, not the plan failing.
A ratio that counts it as a failure creates pressure to schedule preventive work on items that do not warrant it, which consumes hours that higher-criticality assets needed. The metric ends up misallocating exactly the resource it was meant to protect.
The more informative splits
Several breakdowns tell you more than the headline ratio.
- Emergency work as a share of reactive work. Reactive work you attend next week is very different from reactive work that stops a building today.
- Repeat failures on the same asset — the clearest indicator that either the interval or the task content is wrong.
- Reactive work arising on assets that are on the planned schedule, which is the direct measure of whether the schedule is doing its job.
- Planned tasks completed on time, since a schedule that exists but runs late is not delivering the prevention it claims.
Watch the direction over a long window
Month-to-month movement in the ratio is mostly noise: one major failure distorts a small department's figures completely.
A twelve-month rolling view smooths that and shows whether the underlying position is improving. It also matches the timescale on which preventive maintenance actually works — an interval change made in spring shows its effect over the following year, not the following month.
Use it as a prompt, not a target
The ratio is at its most useful as a question generator. A sharp move invites an explanation: which assets, which failure modes, was there a change in how work is classified.
Set as a target with consequences attached, it reliably produces the number without producing the outcome. That is not cynicism about maintenance departments; it is what happens to any single metric that is made to carry more weight than it can bear.