Compound Interest Calculator
Calculate how your investments grow over time with compound interest. Add regular contributions to see the power of consistent investing.
Compound Interest Calculator
Calculate how your investments grow over time with compound interest and regular contributions
💡 Rule of 72: At 7% interest, your money will double in approximately 10.3 years.
Formula
A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) - 1) / (r/n)]Where A = Final amount, P = Principal, r = Annual rate, n = Compounding periods, t = Years, PMT = Contribution
How to Use
- 1Enter initial investment — Input the amount you're starting with.
- 2Set interest rate — Enter the expected annual interest rate.
- 3Choose investment period — Select how many years to invest.
- 4Select compounding frequency — Choose how often interest compounds (monthly is common).
- 5Add contributions (optional) — Enter regular contributions to your investment.
- 6View results — See your projected balance and growth chart.
Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on both the initial principal and accumulated interest. Your money grows faster because you earn interest on your interest.
How does compounding frequency affect returns?
More frequent compounding yields higher returns. Monthly compounding earns slightly more than annual compounding at the same rate.
What is the Rule of 72?
Divide 72 by your interest rate to estimate doubling time. At 8% interest, money doubles in about 9 years (72 ÷ 8 = 9).
What is a realistic interest rate?
Stock market averages 7-10% annually. High-yield savings offer 4-5%. CDs and bonds typically offer 3-6%.