Repair vs Replace Equipment

How this works

Repairing and replacing equipment rarely last the same number of years, so comparing their raw price tags is misleading. This engine converts each option's upfront cost into an equivalent annual cost using the capital recovery factor, then adds each option's own ongoing maintenance and downtime cost. The option with the lower annualized total is the economically preferred choice.

The classic "50% rule" (replace once repair cost exceeds half of replacement cost) is shown as a supplementary check, not the deciding factor, because it ignores remaining life, downtime, and ongoing maintenance cost. When the two disagree, the annualized-cost result governs.

Assumptions

• Each option's costs are treated as a level annual amount over its own expected life, with no cost escalation or inflation modeling
• Downtime hours and their cost per hour are constant year to year within each option
• The discount rate, when used, applies uniformly to both options
• Salvage value is realized once, at the time of replacement, and offsets the replacement capital cost

Limitations

• Does not model multiple future replacement cycles, only a single comparison cycle
• Does not model financing terms, taxes, or depreciation
• Does not model probability-weighted failure risk beyond the downtime-hour estimate provided

Sources

The equivalent annual cost method and capital recovery factor follow Blank and Tarquin, Engineering Economy (8th edition), and NIST Handbook 135, the Life-Cycle Costing Manual for the Federal Energy Management Program.

Worked example

A machine needs a $25,000 repair and would run another 2 years, with 120 hours of downtime expected per year at $250 an hour. A comparable new machine costs $90,000, lasts 12 years, and would cut annual downtime to 15 hours. Annualizing the repair's $25,000 over 2 years plus its downtime cost comes to about $42,500 a year. Annualizing the replacement's $90,000 over 12 years plus its lower downtime cost comes to about $11,250 a year, roughly $31,000 a year less than repairing. Even though the repair cost is only about a quarter of the replacement cost, well under the common 50% rule threshold, replacing is still the cheaper choice once the shorter remaining life and higher downtime of the repaired machine are both accounted for.

Common use cases

• Production machinery nearing the end of a repair-worthy life
• Forklifts and material handling equipment
• HVAC and facility mechanical systems
• Packaging and conveyance equipment