Preventive vs corrective maintenance ratio calculator
See how much of your maintenance is planned and how much is reactive: your preventive share, your PM:CM ratio, and how much work you would need to move to planned to hit your target.
One period (e.g. last month)
Use hours or work-order counts, but the same unit for both. Costs can be in any currency.
Working: preventive share = 120 ÷ (120 + 80) × 100 = 60%. Ratio = 120 ÷ 80 = 1.5 : 1.
Plan preventive maintenanceHow to calculate your maintenance ratio
Four steps. Every number is an input you control, and nothing leaves your browser.
Choose one period, such as last month or last quarter.
Enter planned or preventive maintenance hours, or work orders, for the period.
Enter reactive or corrective maintenance hours, or work orders, in the same unit.
Optionally add costs and a target preventive share, then read the ratio and the gap to your target.
What you need to know
The preventive vs corrective maintenance ratio compares planned work (inspections, servicing and scheduled replacements done before something fails) with corrective work (repairs after a breakdown or fault). Enter the hours, or the number of work orders, for each type over the same period. The calculator returns the preventive share (preventive ÷ total × 100, often called planned maintenance percentage or PMP), the corrective share, and the PM:CM ratio (preventive ÷ corrective, for example 3 : 1).
Add the cost of each type of work to see what share of your maintenance spend goes on reactive repairs, and the cost per hour or per work order of each. Corrective work often costs more per job because it can bring downtime, rush parts and overtime with it. Your own figures will show whether that holds for your assets.
Set a target preventive share and the calculator shows how many hours or work orders you would need to move from reactive to planned to reach it. Many maintenance teams use 80% planned and 20% reactive as a rule of thumb, but the right target depends on your assets: running to failure can be the cheaper choice for low-cost items that are easy to replace, while critical equipment justifies more preventive work.
Use one period for both inputs (a month or a quarter works well) and count the same way each time so the trend means something. In Asetavo’s maintenance module, preventive schedules and work orders sit against each asset with their downtime and cost, so the split is there when you need it.
Ready to move beyond the calculator?
Plan preventive maintenance and keep a complete work-order history for every asset.
- PM schedules by days, weeks or months
- Work orders with priority, assignee, downtime and cost
- Calibration records and “due soon” lists
Questions, answered
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