What is the true cost of a purchase?

The sticker price plus the growth that money would have earned invested over the years you keep the thing, plus running costs, minus resale value. A $1,200 purchase held five years at a 6% alternative return truly costs about $1,600 before running costs.

What is opportunity cost in simple terms?

What the money could have become if you had not spent it. Spending $1,200 today at a 6% yearly return means giving up roughly $400 of growth over five years — an invisible part of the price.

How do I calculate cost per use?

Divide the true cost (price plus missed growth and running costs, minus resale) by how many times you will honestly use the item. Under a dollar per use is excellent for most goods; tens of dollars per use suggests renting or borrowing instead.

True Cost of a $2,500 Purchase Calculator

What the price is made of

The honest receipt

The same money, left to grow

The solid line is what this money becomes if invested instead. The dashed line is the sticker price standing still. The gap is the invisible cost. Hover any year.

Before you buy

How we calculate

What is included

Three layers on top of the sticker: the growth this money would have earned over your horizon (compounded monthly at your rate), the running costs it drags along (each month’s cost also missing its own growth), and — on the plus side — the resale money you get back at the end. Cost per use divides the total by your honest usage.

What is estimated or left out

A thinking tool, not a verdict on joy. Inflation is not subtracted from the return — use a real (after-inflation) rate like 3–4% if you want everything in today’s dollars. Value that is not money — time saved, health, delight — is yours to add; the point is to see the full price before deciding it is worth it.

The formula, in plain words

missed growth = price × (1 + rate)^years − price
running total = running costs, each month, plus their own missed growth
money back    = resale price when you sell
true cost     = price + missed growth + running total − money back
cost per use  = true cost ÷ (uses per month × 12 × years)

Common questions

Isn’t this just talking myself out of everything?: No — it is paying the real price on purpose. Some things survive the honest receipt easily: you use them daily, they last, they matter. The ones that do not survive it were going to disappoint you anyway; now they do it before the money leaves.
What return should I use?: 4% if the alternative is a savings account, 6–7% if it is long-term investing, 20%+ if you carry credit-card debt — because then every purchase is effectively borrowed at card rates, and paying the card first beats almost any object.
What is a good cost per use?: Compare it with renting the same thing or buying the experience once: a $1,200 machine at 40¢ per use beats a $6 class every time; at $12 per use, the class wins. The chip “+ Your hourly pay” adds an even blunter unit: hours of your life.