Your equipment
Your assumptions
Leave the repair quote blank for a working unit with no quote: the comparison is then replace now against run it until it fails. The discount rate is what a dollar next year is worth to you today. The typical lives are rule-of-thumb figures you can overwrite in the last column; they are not measured lives of your units.
Upload or paste your equipment, then click Analyse.
Result
Assets, strongest case for replacing first
Cost a year is each path's expected cost over your horizon spread evenly by year, with a credit for the remaining life of what is in service at the end. Repair up to is the break-even quote: a quote under it favours repairing.
| Asset | Age / life | Fails within 3 years | Repair a year | Replace a year | Repair up to | Verdict |
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How it is calculated
Each unit fails on a Weibull curve whose mean is its life; the chance it fails in the coming year given its age is computed from that curve. Repair pays the quote now and leaves the unit at its current age (a repair does not make it younger); the first time it fails afterwards it is replaced. Replace pays the replacement cost now and starts a new unit at age zero. Every failure costs the replacement plus your extra cost of an unplanned failure, and every year a new unit is in service saves the yearly savings you enter. Costs are discounted yearly over your horizon, and whatever is in service at the end gets a straight-line credit for its remaining life. The break-even quote is the repair price at which both paths cost the same. The table also shows whether the 50% rule of thumb would say replace, and whether the verdict changes if the life is 25% shorter or 25% longer.
Not modelled: the real condition of your unit, brand and installation quality, maintenance history, rebates and tax credits, depreciation and tax treatment, code or refrigerant changes that force a replacement, a repair that fixes only part of the problem, tenant turnover, and a replacement that costs more or less next year. Unverified: the arithmetic is checked in unit tests against hand-calculated cases; the typical lives and the wear-out curve are planning assumptions and have not been fitted to failure data for your equipment.
Common questions
Should I repair or replace a water heater, furnace or appliance?
Compare what each path costs over the years you will own the building, not the size of today's quote. Repairing leaves the unit as old as it was, so the chance it fails again stays high; replacing resets that chance and may cut utility cost. This tool prices both paths over your horizon, including the cost of an unplanned failure, and shows the repair price at which the two break even.
What is the 50% rule and why does this tool not just use it?
The rule of thumb says replace when the repair costs more than half of a new unit, or when the unit is past half its life and the repair costs a third or more. It ignores what a failure costs you, what a new unit saves in energy, and how steeply this kind of equipment wears out. The tool shows whether the rule would say replace next to its own answer, so you can see where they disagree.
What is the break-even repair quote?
It is the most a repair can cost before replacing is cheaper over your horizon. If the quote in hand is under it, repair; if it is over, replace. It falls as the unit ages, because an old unit is likelier to fail again soon and the repair buys less.
Where do the typical lives come from?
They are rule-of-thumb planning figures (for example 12 years for a tank water heater, 18 for a furnace, 15 for central air, 22 for an asphalt roof) that you can overwrite per asset. They are starting points, not measured lives of your unit. Enter your own if a technician or your history says otherwise; the tool also shows how the answer changes if the life is 25% shorter or longer.
What does wear-out sharpness mean?
It is how quickly the failure chance climbs as a unit approaches the end of its life. At 1 a unit has no memory and fails at random at any age; at 3, the default, most units fail in a band around their typical life; at 5 or more, almost all fail near it. Leave it at 3 unless you have reason to change it.
What does an unplanned failure cost?
More than the unit: an emergency call-out, a rush install, lost rent while a tenant has no heat or hot water, and sometimes water damage. The default adds 200 dollars for each failure and you can change it for all assets. Raising it pushes the answer toward replacing before the unit fails.
Does it work for a homeowner, not just a landlord?
Yes. Any owner deciding between a repair quote and a replacement on equipment with a rough life expectancy can use it: water heater, furnace, air conditioner, heat pump, roof, refrigerator, washer, dryer, dishwasher, range, disposal or sump pump. Put the years you expect to keep the property in the horizon.
Is my property list uploaded anywhere?
No. The file is read and analysed in this browser tab. Nothing is sent to a server, there are no accounts or cookies, and the tool never stores your assets. It works offline once the page has loaded.