Opportunity cost in numbers
Every dollar spent today is a dollar that cannot grow. At 7% a year, money roughly doubles every ten years, so $500 today is about $1,000 in a decade, $3,800 in 30 years and $7,500 in 40. Economists call that the opportunity cost of spending.
Use the number as a pause button, not as guilt. Waiting 48 hours before non-essential purchases is a simple rule that filters out many impulse buys while still allowing the ones you really want.
Common questions
What is opportunity cost?
The value of the best alternative you give up, here the future value of money you spend instead of investing.
What return should I use?
7% is a common long-term stock market planning figure after inflation is ignored; use 4% to 5% for a cautious view.
This calculator gives estimates for planning. Real returns, rates and prices change, so treat the result as a guide rather than a promise. Read how we build and check our calculators.