The Rule of 72: How Long to Double Your Money?
Calculate your exact doubling time with our [Rule of 72 Calculator](/calculators/finance/rule-of-72-calculator).
The Formula
Years to double = 72 divided by Annual Return Rate
Complete Doubling Time Table
| Annual Return | Years to Double | Context |
|---|---|---|
| 2% | 36 years | Regular savings account |
| 4% | 18 years | HYSA 2026 |
| 6% | 12 years | Balanced fund |
| 7% | 10.3 years | Stock market real return |
| 8% | 9 years | Historical S&P 500 real |
| 10% | 7.2 years | S&P 500 nominal |
| 12% | 6 years | Aggressive growth |
| 18% | 4 years | Warren Buffett average |
| 24% | 3 years | Credit card debt — you LOSE |
The Debt Side: Rule of 72 Works Against You
Credit card debt at 24% APR doubles every 3 years:
- $5,000 balance → $10,000 in 3 years (minimums only)
- $10,000 → $20,000 in 3 more years
- $20,000 → $40,000 by year 9
This is why high-interest debt is a financial emergency. The math attacks your wealth faster than most investments can build it.
The Inflation Warning
At 3% inflation: purchasing power halves in 72/3 = 24 years. Money in a 1% savings account loses purchasing power every year.
The 10-Year Reality Check
Before every major financial decision: What does this money become in 10 years at 8%?
Investing $10,000: Doubles to $20,000 by 2035.
Carrying $10,000 credit card debt at 24%: Would have quintupled to ~$50,000 in debt-compounding costs.
Use our [CAGR Calculator](/calculators/finance/cagr-calculator) to find what rate you are actually earning on current investments.
Related Tools
- [Compound Interest Calculator](/calculators/finance/compound-interest-calculator) — Precise projection at any rate
- [Savings Goal Calculator](/calculators/finance/savings-goal-calculator) — How long to reach any target
- [Credit Card Payoff Calculator](/calculators/finance/credit-card-payoff-calculator) — Stop the debt compounding