Compound Interest Calculator
See how your investment grows with the power of compounding
Investment Details
Growth Summary
Enter investment details to see growth summary
Year-by-Year Growth
Year-by-year breakdown will appear here
What is the Compound Interest Calculator?
A compound interest calculator shows how money grows when interest is earned not just on your original deposit, but on the interest already accumulated. It's the reason $10,000 invested at 30 looks completely different from $10,000 invested at 45. Investors, savers, and anyone comparing accounts at Vanguard, Fidelity, or a high-yield savings account use this tool to see realistic projections. CalciHub's version shows year-by-year growth so you can see the snowball effect in action, not just the final number.
How Does It Work?
Compound interest is interest calculated on both the initial principal and accumulated interest. The more frequent the compounding, the faster growth happens.
Formula: A = P(1 + r/n)^(nt)
A = final amount (principal + interest)
P = principal (initial deposit)
r = annual interest rate (as a decimal, e.g., 0.07 for 7%)
n = number of times interest compounds per year
t = time in years
How to Use CalciHub's Compound Interest Calculator
1. Enter the starting principal — the amount you're investing or saving.
2. Enter the annual interest rate.
3. Choose how often interest compounds: daily, monthly, quarterly, or annually.
4. Set the time period in years.
5. Optionally add a monthly contribution to see how regular deposits change the outcome.
6. Click Calculate for your final balance and a year-by-year breakdown.
Tip: Switch between compounding frequencies — daily compounding does beat annual, though the difference is smaller than most people assume.
A Quick Example
David puts $5,000 into a high-yield savings account earning 5% annual interest, compounded monthly. He leaves it alone for 10 years.
Principal: $5,000
Annual rate: 5%
Compounding: Monthly
Time: 10 years
Final balance: $8,235.05
Total interest earned: $3,235.05
David's money grew by about 65% without him doing anything. If he'd started 10 years earlier and left it for 20 years total, that same $5,000 would become $13,535 — nearly triple the original investment.
Frequently Asked Questions
Simple interest is calculated only on the original principal, every single time. Compound interest grows on top of itself — interest earns interest. Over long periods, the gap between the two becomes dramatic. A $10,000 deposit at 6% simple interest for 20 years gives you $22,000. Compounded monthly, you'd end up with about $33,100.