How it works

Total cost: price, plus anything it needs before it works, plus running costs for every year you keep it, minus what you can sell it for at the end.
Uses: how often you will use it, from your history, never your plans, multiplied out over its life. For something meant to start a new habit there is no history, so the count is halved: aspirational estimates run about double.
Verdict: for most household goods, under $1 a use is excellent, $1 to $10 is defensible, and over $10 needs a specific reason.

The formula does not suit everything. Safety equipment such as smoke alarms and fire extinguishers should ideally never be used, and still has to be bought, tested and replaced on schedule. Single-event items are judged on whether the event matters and whether renting would do. And when two options land close together, let comfort break the tie: a tool you enjoy gets used more.

The figures come from the guide Price Per Use: A Better Way to Decide If Something Is Worth Buying, which explains each one and the exceptions.

Sources

U.S. Fire Administration: smoke alarms (test monthly, replace every 10 years)

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