Compound Interest Calculator – Growth Over Time
Calculate compound interest and final balance for any investment. See how interest compounds monthly, quarterly, or annually.
📈 Finance📐 A = P(1 + r/n)^(nt)
Principal ($)
Annual interest rate (%)
Compounding (times/year)
Time (years)
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Compound Interest Calculator – Growth Over Time | A = P(1 + r/n)^(nt) | $ total |
Step-by-Step Examples
Example 1
$10K at 7%, 10yr Monthly
$10,000 at 7%, compounded monthly, 10 years.
- A = $10,000 × (1+0.07/12)^120
- = $20,097 | Interest earned: $10,097
✓ $20,097
Example 2
Retirement: $50K at 8%, 25yr
$50,000 at 8%, monthly, 25 years.
- Final: $370,453 | Growth: 641%
✓ $370,453
Example 3
Simple vs Compound
$10,000 at 7% for 10 years.
- Simple: $17,000 | Compound monthly: $20,097
- Compounding earns $3,097 more!
✓ $20,097 compound
Real-World Applications
Investors
See how investments grow over time.
Savers
Compare savings account rates.
Students
Learn the power of compound interest.
Retirement Planners
Project investment growth.
Common Mistakes to Avoid
⚠️
Ignoring inflation
A 7% return with 3% inflation = 4% real return. Your money grows in nominal terms but buying power grows slower.
⚠️
Withdrawals destroy compounding
Even small regular withdrawals dramatically reduce compound growth. Let investments compound undisturbed as long as possible.
Frequently Asked Questions
How does compound interest work? ▾
Interest is earned on the principal AND on previously earned interest. Each period you earn interest on a larger base, so growth accelerates over time.
Compounding frequency matters? ▾
More frequent compounding = slightly more growth. $10K at 7% for 10 years: annually=$19,672, monthly=$20,097, daily=$20,113.
Rule of 72? ▾
Divide 72 by the interest rate to estimate how many years to double your money. At 7%: 72/7 = 10.3 years to double.
Best compound interest investments? ▾
Index funds (7-10% historical), high-yield savings (4-5%), CDs, bonds. Start early — time is the most powerful factor.