Free calculator
What does it actually cost?
The price tag is the smallest number in the transaction — it's just the only one the shop shows you. Put anything in below and see what the money would be worth if you kept it instead.
7% is roughly the long-run real return of a broad global equity index after inflation. Drop it to 4% to be conservative.
If you kept it and invested it
€89,780
after 20 years at 7% a year.
An illustration of opportunity cost, not a forecast, and not financial advice.
Why the small things cost the most
Ask someone what their Friday night costs and they will say forty euros. It is the correct answer to the wrong question, and it is the reason habit spending survives every budget anyone has ever written.
€40 a week is €2,080 a year. Left invested at a 7% real return for twenty years, those contributions become roughly €95,000 — not because any single Friday was expensive, but because you did it a thousand times and the compounding did the rest.
| The habit | A year of it | Over 20 years |
|---|---|---|
| A €6 coffee, five days a week | €1,560 | €71,000 |
| €30 a month of subscriptions | €360 | €16,400 |
| €40 of drinks every weekend | €2,080 | €95,000 |
| €12 of takeaway lunches, twice a week | €1,248 | €57,000 |
| A €429 pair of headphones, once | €429 | €1,660 |
At a 7% real annual return. Look at that list again: the single most expensive line is the cheapest individual purchase.
Knowing the number isn't the hard part
There is a reasonable objection to all of this: if the maths were enough, a calculator would have fixed impulse spending years ago. It isn't, and it hasn't. Impulse buying is a dopamine loop, not an arithmetic error — the spike arrives before the purchase, on the anticipation, and it wants to be resolved.
Which is why every pause-before-you-buy app quietly fails. A cooldown timer does not resolve the urge, it parks it, and a parked urge comes back at eleven at night with the tab already open. What works is answering it twice: once with a number this size, and once with an ending.