Compound Interest Calculator
See what your money grows to when interest earns interest. Enter a present value and an annual rate, choose monthly, quarterly, or annual compounding, add a time length and any recurring deposits, and get the future value, total deposits, total interest, total yield, and a period-by-period balance table — computed in your browser.
Enter the starting money and rate
Pick a currency symbol, type the present value (the amount you start with) and the nominal annual interest rate in percent — 4 means 4% a year.
Set compounding and time
Choose how often interest compounds — monthly, quarterly, or annually — then enter a time length in Days, Weeks, Months, Quarters, or Years.
Add deposits, then Calculate
Optionally add a recurring payment (monthly, quarterly, or yearly, deposited at the start or end of each period), press Calculate, and read the future value, interest, yield, and the compound interest table. Copy the results or Reset to start over.
How the math works
- What formula does this calculator use?
- The standard compound interest formula: the amount after n years is Aₙ = A₀ · (1 + r/m)^(m·n), where A₀ is the present value, r the nominal annual rate, m the compounding periods per year (12, 4, or 1), and n the number of years. Recurring payments are added each payment period and compounded from then on.
- What do Start and End mean for additional payments?
- End deposits each payment at the end of a period (the ordinary-annuity default); Start deposits at the beginning, so every payment earns interest for one extra period and ends slightly higher.
- How are Days and Weeks handled?
- This calculator converts time to years with the conventional factors: 1 year = 365 days, 52 weeks, 12 months, 4 quarters. So 365 Days at 10% annually equals 1 Year — a 366th leap day is not special-cased.
- What is total yield?
- Total interest divided by total deposits (present value plus all payments), in percent. With zero deposits it reads 0% instead of dividing by zero.
- Worked example
- $35,000 at 3% compounded monthly for 8 years: 35,000 · (1 + 0.03/12)^(12·8) = $44,480.40, so total interest is $9,480.40 and total yield is 27.09%.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Copy results uses your clipboard only. This tool is for estimation, not financial advice.