Almost every purchase that turns out badly was decided in the wrong order. Someone starts with a product, then works backwards to justify it, and the research that follows is not an investigation but a search for permission. The reviews get read, the specifications get compared, and the original question — whether this is the right thing at all — never gets asked.
The alternative takes ten minutes and no research. Five questions, answered honestly and in sequence, will settle most large purchases before you open a single comparison table. When they do not settle it, they at least tell you what the remaining question actually is.
One: what has to be true for this to be worth it?
Not what the product does. What has to be true about your life for the product to earn its place. A stand mixer is worth it if you knead dough regularly; a treadmill is worth it if darkness rather than motivation is what stops you running.
Write the condition down as a sentence. If you cannot, that is the answer. If you can, you now have a test you can apply to your last six months rather than to your intentions, and the honest version of that test is usually decisive.
The value of this question is that it moves the decision from the product to your circumstances, where it belongs, and where marketing has no purchase.
Two: what is the constraint I keep forgetting?
Nearly every category has a constraint that is obvious afterwards and invisible beforehand. For appliances it is where the thing will live. For clothing it is the dimension that cannot be altered. For anything with a subscription it is the ongoing cost rather than the purchase price.
The pattern is that the constraint is rarely the thing being advertised. Air fryers are sold on capacity and limited by counter depth. Laptops are sold on processors and limited by soldered memory. Bikes are sold on components and limited by where you can store them.
Name your constraint and measure it before you shop. Then treat it as a hard requirement rather than a preference, and let the specification fall out of it.
A reliable way to find your constraint is to look at what you have already replaced or stopped using. The appliance in the cupboard, the coat that never gets worn, the equipment that was too awkward to set up — each of those is a record of a constraint you did not account for last time. People tend to repeat the same oversight across categories, because it usually reflects something stable about their circumstances rather than a one-off mistake.
It is also worth distinguishing between a constraint and a preference, because they behave differently. A constraint is a fact about your situation: the width of the alcove, the height of the doorway, the number of hours you have. A preference is something you would like. Preferences can be traded off against each other; constraints cannot, and treating one as the other is how people end up with something that does not fit.
Three: what does this cost per year?
The purchase price is the least informative number attached to most products. What matters is the total over the period you will own it, including consumables, and divided by the years you will use it.
| Category | Hidden ongoing cost | Effect |
|---|---|---|
| Electric toothbrushes | Replacement heads | Often exceeds the handle within a couple of years |
| Printers | Ink or toner | Can dwarf the machine entirely |
| Footwear | Resoling, or replacement | Repairable construction changes the maths completely |
| Cookware | Coating lifespan | Non-stick is a consumable regardless of price |
| Anything subscription-linked | The subscription | The hardware price becomes almost irrelevant |
Working this out frequently reverses a ranking. The cheaper option with expensive consumables loses to the pricier one with cheap ones, and the difference is usually larger than any discount you were weighing up.
Four: what happens when part of it fails?
Everything fails eventually, and what separates a good purchase from a poor one is often whether the failure is repairable or terminal.
The questions are concrete. Are the parts that wear replaceable? Are they available, and from more than one source? Is the battery sealed? Does the manufacturer publish repair information, and are there independent people who service these?
A product designed around repair costs more and lasts longer, and the difference compounds with how heavily you use it. A product that is sealed is not necessarily a bad purchase; it is a purchase with a known end date, which should be reflected in what you pay. The full version of this argument is in buy it for life versus replace it twice.
Five: what would make me return it?
Decide the failure conditions before you buy, while you are still capable of being objective. Write down two or three specific things that would mean this was the wrong choice — a fit that does not settle, a noise you cannot live with, a routine you do not adopt.
Then check the returns policy against them. A generous return window is worth more than a modest improvement in specification, because it converts an irreversible decision into a reversible one. For anything you cannot evaluate quickly — shoes, anything you have to live with, and above all a mattress — the policy is doing the work a test would otherwise do.
Deciding the failure conditions in advance also protects you from the strongest force in consumer psychology, which is the desire to be right about a decision you have already made.
When to break the rules
These questions are about avoiding regret, not about minimising spending. Some purchases are for pleasure, and pleasure is a legitimate reason to buy something. A decorative object, an indulgence, something bought because you wanted it — none of these need to survive a cost-per-year analysis.
The distinction worth preserving is honesty about which kind of purchase you are making. Trouble comes from buying for pleasure while telling yourself it is for utility, because then the justification has to keep growing to support a decision it never actually made.
What to know before you buy
- Write the condition down. If you cannot state what has to be true, do not buy it yet.
- Measure the constraint before you look at products.
- Cost it per year, consumables included.
- Check what is replaceable and whether parts are available.
- Define your return conditions in advance and read the policy against them.
- Be honest about pleasure purchases. They are fine; they just need a different justification.
Does this work for small purchases too?
It works and it is usually not worth the time. The value scales with the amount at stake and with how hard the purchase is to reverse. For anything cheap and returnable, buying and finding out is faster and often cheaper than deliberating.
How long should I wait before buying?
Long enough to answer question one honestly, which for most people is a few days rather than weeks. The point of waiting is not discipline for its own sake — it is that the answer to question one changes once the initial enthusiasm has passed, and the answer you get afterwards is the more reliable one.
What about a genuinely good deal?
A discount on something that fails questions one to four is not a good deal. It is a smaller amount of money spent on the wrong thing. Work out whether the discount is real first, which is a separate skill covered in how to tell a real sale from a fake one.
None of this requires expertise in any particular category. It requires being willing to answer five awkward questions before the enjoyable part of shopping begins, which is precisely why almost nobody does it — and why the people who do end up with fewer things they regret.
