Repair or replace: the threshold that decides it

A repair quote is the moment the upgrade question stops being abstract. The number on the quote is compared against a new machine, and the comparison is almost always made wrong, because the two numbers are not the same kind of thing.

The mistake

A 300 repair on a laptop worth 650 feels like half the value of the machine, so the instinct is to replace. A 900 new machine feels like three repairs, so the instinct is to repair. Both instincts compare a one-off cash amount against a sticker price and ignore the years in between.

The question that actually decides it is different: how much does each option cost per year, counting the value each one consumes.

The threshold, written out

A repair is worth doing when keeping costs less per year than replacing:

repairs per year < (new price - new machine end value - current resale) / years you would keep the new one

Everything on the right side is knowable before you decide. The defaults on the calculator give a line of about 150 per year for a 1999 machine kept five years. A single 300 repair every four years averages 75 per year, which sits under the line, so repairing wins. A machine that needs 400 every year sits well above it, and replacing wins.

Why one big repair is not the same as a high repair rate

A 300 battery replacement on a four-year-old machine is 75 per year averaged out. A machine with a failing hinge, a swelling battery and a dying fan is 400 or more per year, every year, and the failures start arriving together. The second case is the one where replacing is cheaper, and it is also the case people describe as "it is falling apart".

So before deciding, do the arithmetic on the last three years of receipts rather than on the one quote in front of you.

What the quote does not tell you

A repair restores one function. It does not restore performance, battery life, warranty coverage, or the ability to run the next operating system. Those are not money, but they are the reasons people replace a machine that is still repairable.

The honest split is:

• Economically repairable: repair rate below the threshold, and the machine still does the work.
• Economically replaceable: repair rate above the threshold, or two major failures inside twelve months.
• Neither: repair rate below the threshold but the machine no longer does the work. This is a capability purchase, and it should be described that way rather than disguised as a saving.

A note on extended warranties

An extended warranty converts unpredictable repairs into a fixed annual cost. Add that premium to the repair rate before comparing, and remember that the warranty usually expires exactly when failures become likely.

Use your own numbers

The threshold moves with three inputs, so any article that gives a single number is guessing. Enter your quote, your resale value, and your expected years, and read the line the calculator prints beside the payback field. If your repair rate is under it, repair. If it is over it, replace. If it is close, the decision is a coin flip on non-financial grounds, which is a fine way to decide as long as you know that is what you are doing.