Opportunity cost is the most important concept in personal finance that most people never apply. Every $100 spent today is not just $100 — it's $100 plus the compound growth it would have generated over your investment time horizon.
The compound opportunity cost calculator
🧮 What does this purchase actually cost?
Future value of this purchase
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Purchases that change when you run this math
| Purchase | Nominal cost | 25-year opportunity cost (7%) |
|---|---|---|
| Daily $6 coffee (monthly) | $180/month | $113,000 over 25 years* |
| $800 luxury item | $800 | $4,340 |
| $35,000 new car (vs $20k used) | $15,000 difference | $81,400 |
| $2,400 vacation upgrade | $2,400 | $13,020 |
| $400,000 home (vs $300k) | $100,000 difference | $542,700 |
*Monthly investment calculation
When opportunity cost thinking goes too far
The point of this math isn't to never spend money. It's to make the trade-off visible and conscious. A $2,400 vacation that creates lasting memories and relationship investment may be worth $13,020 in future value. A $2,400 impulse purchase of something you forgot you owned 6 months later — that's the target of this analysis.
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