usefulweb.site Repair or Replace

Everyday problem-solving

Repair or Replace

Fix it or buy new? The 50% rule plus a cost-per-year check, with a clear verdict.

Shown in results only; no conversion is performed.

years
years

Typical total life of this kind of item; also used for the new one unless set below.

years
years
per year

Energy, water, consumables.

per year
%

Your estimate for the extra life period; an assumption, not a statistic.

Defaults to the current repair quote.

%

Try an example: Washing machine with a failed drum bearing · Laptop with a dead battery

How it works

Enter the age and expected lifespan of a broken item, the repair quote, the replacement price and running costs. The tool applies the common 50% rule of thumb and compares the cost per remaining year of repairing versus replacing, including the risk of another failure, and gives a reasoned verdict.

  • 50% rule of thumb: if the repair quote is more than the threshold (default 50%) of the replacement price, replace; otherwise repair. This is a common heuristic, not a law or standard.
  • Expected extra repair cost = P(another failure) × next repair cost (defaults to the current quote).
  • Repair cost per year = (repair quote + expected extra repair cost) ÷ expected extra life + running cost of the old item per year.
  • Replace cost per year = replacement price ÷ lifespan of the new item + running cost of the new item per year.
  • Break-even repair quote = (replace cost per year − old running cost) × extra life − expected extra repair cost (floored at 0).
  • Final verdict follows the cost-per-year comparison, because it accounts for remaining life, failure risk and running costs; the 50% rule is shown as a cross-check.

For scripts and AI agents

  • JSON API: POST https://repairorreplace.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://repairorreplace.usefulweb.site/mcp · tool name repair_or_replace
Example request
curl -s -X POST https://repairorreplace.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{"itemName":"Washing machine","currency":"EUR","itemAgeYears":8,"expectedLifespanYears":11,"replacementPrice":550,"repairQuote":320,"lifeAfterRepairYears":3,"runningCostOldPerYear":75,"runningCostNewPerYear":55,"failureProbabilityPercent":35,"ruleThresholdPercent":50}'
Feedback