Compound Interest Calculator

Project your investment growth or solve for missing variables.

What this calculator helps you do

Estimate how savings grow when interest is compounded and regular deposits are made. You can either project a future balance or solve for the deposit, time, rate, or starting amount needed to reach a goal.

  • Initial balance is what you have saved today.
  • Periodic deposit is the contribution you plan to add each compounding period.
  • Duration and interest rate describe how long the money grows and how quickly it earns returns.
  • Deposit timing lets you choose whether contributions happen at the beginning or end of each period.

Your results will appear here

Fill out the form and click "Calculate" to see your investment projection or solve for a missing variable.

How It's Calculated

The calculator finds the future value by combining the growth of the initial principal with the growth of periodic deposits (an annuity). The standard formula is:

$$ FV = P\left(1 + \frac{r}{n}\right)^{nt} + PMT \times \left[ \frac{\left(1 + \frac{r}{n}\right)^{nt} - 1}{\frac{r}{n}} \right] \times \left(1 + \frac{r}{n}\right)^{\text{timing}} $$

FV: Future Value

P: Initial Principal

r: Annual Interest Rate

n: Compounding/Deposit Periods per Year

t: Number of Years

PMT: Periodic Deposit

timing: This exponent is 1 if deposits are at the beginning of the period (annuity due), and 0 if at the end (ordinary annuity).

Assumptions: Calculations assume that interest is compounded at the same frequency as deposits are made (e.g., monthly deposits mean monthly compounding). The model uses a nominal annual interest rate and does not account for fees or taxes.