Compound Interest Calculator
Enter your principal amount, annual interest rate, investment period in years, and compounding frequency (monthly, quarterly, or annually) to see the final amount and total interest earned. The calculator uses the standard compound interest formula: A = P(1 + r/n)^(nt).
Compounding frequency makes a real difference — the same rate compounded monthly yields more than annually because interest earns interest more frequently. This tool lets you compare scenarios by changing the frequency and seeing the result update instantly.
Useful for savings projections, loan cost estimates, investment comparisons, and understanding how compounding frequency affects returns. Everything runs in your browser — no data is sent anywhere.
By The Paper Room Editorial Team — Calculators
Frequently asked questions
What does compounding frequency mean?▼
Compounding frequency is how often interest is calculated and added to the principal. Monthly compounding (12 times/year) adds interest every month, so the next month's interest is calculated on a slightly larger balance. More frequent compounding yields slightly more total interest for the same annual rate.
What's the formula used?▼
A = P(1 + r/n)^(nt), where P is principal, r is annual rate (as a decimal), n is compounding frequency per year, and t is time in years. Total interest = A - P.
Is this accurate for real-world investments?▼
This gives an idealized calculation assuming a fixed rate over the entire period. Real investments have variable returns, fees, taxes, and inflation — this is a useful approximation for planning, not a guarantee of actual returns.