Compound Interest Calculator
NewSee how your money grows over time with compound interest. Accounts for principal, monthly contributions, interest rate, and compounding frequency to show your future balance and total interest earned.
Compound Interest Calculator
Enter your figures below
See exactly how your money compounds over time. Enter a starting balance, monthly contributions, and an expected annual return to project your future balance — with a clear breakdown of contributions vs. interest earned.
- 01
Enter your initial investment (principal) and any monthly contributions you plan to make.
- 02
Set the annual interest rate and your time horizon in years.
- 03
Choose how often interest compounds — monthly, quarterly, or annually.
- 04
Hit Calculate to see your projected balance and how much comes from growth vs. contributions.
- Long-term investors modeling retirement or goal-based savings growth.
- Anyone comparing the impact of monthly contributions vs. a lump-sum investment.
- Students learning how compound frequency affects total returns over time.
Why does compounding frequency matter?+
The more frequently interest compounds, the faster your money grows — monthly compounding earns interest on interest 12 times per year vs. once with annual compounding, which adds up significantly over decades.
What's a realistic long-term return rate?+
Historical S&P 500 average is ~7–10% annually before inflation. For conservative planning use 5–6%; for optimistic use 8–10%. Past performance doesn't guarantee future results.