Annuity & Savings Calculator

Find the future value of regular deposits into a savings plan or annuity.

The formula

The future value of an ordinary annuity, a series of equal payments made at the end of each period (typical savings plans). \(PMT\) is the periodic payment, \(i = r/n\) the periodic rate, and \(N = nt\) the total number of periods.

$$FV = PMT \times \dfrac{(1 + i)^{N} - 1}{i} \quad\text{or}\quad FV = PMT \times \dfrac{\left(1 + \frac{r}{n}\right)^{nt} - 1}{\frac{r}{n}}$$

The regular payment required to accumulate a target future value \(FV\) with an ordinary annuity, where \(i = r/n\) is the periodic rate and \(N = nt\) the total number of periods.

$$PMT = FV \times \dfrac{i}{(1 + i)^{N} - 1} \quad\text{or}\quad PMT = FV \times \dfrac{\frac{r}{n}}{\left(1 + \frac{r}{n}\right)^{nt} - 1}$$

The future value of an annuity due, where payments are made at the beginning of each period; it equals the ordinary-annuity value multiplied by \((1 + i)\). \(PMT\) is the payment, \(i = r/n\), and \(N = nt\).

$$FV_{due} = PMT \times \dfrac{(1 + i)^{N} - 1}{i}(1 + i) \quad\text{or}\quad FV_{due} = PMT \times \dfrac{\left(1 + \frac{r}{n}\right)^{nt} - 1}{\frac{r}{n}}\left(1 + \frac{r}{n}\right)$$

How to use this calculator

  1. Enter any starting balance (leave 0 if you're starting fresh).
  2. Enter the regular deposit you'll make each period.
  3. Choose how often you deposit and how often interest compounds.
  4. Set the annual interest rate and the number of years.
  5. Read your projected savings, with a year-by-year breakdown below.

How it works

An annuity (in the savings sense) is a series of equal, regular deposits that earn compound interest. Each deposit starts earning interest from the moment it lands, so the earlier a deposit is made, the more it grows. The future value of these deposits is $FV = PMT \times \dfrac{(1 + i)^{N} - 1}{i}$, where $PMT$ is the deposit each period, $i = r/n$ is the periodic rate, and $N = nt$ is the total number of deposits.

This is the math behind retirement accounts, savings plans, and any goal you fund with steady contributions. Two levers dominate the outcome: how much you put in each period, and how long you keep it up — time lets every deposit compound on its own.

Worked example

Deposit \$200 a month for 10 years at a $6\%$ annual rate, compounded monthly. The periodic rate is $i = 0.06/12 = 0.005$ over $N = 120$ deposits, giving a future value of roughly \$32,776 — of which \$24,000 is your own deposits and the rest is interest.

Frequently asked questions

What is an annuity here?

A stream of equal, regular deposits (or payments) that earn compound interest — the basis of most savings and retirement plans.

What's the difference between this and the compound interest calculator?

This one is built around regular deposits over time; the compound interest calculator starts from a single lump sum (though it also allows deposits).

Does deposit frequency matter?

Yes — more frequent deposits, and more frequent compounding, both increase the final balance at the same annual rate.

Can I include money I already have saved?

Yes. Enter it as the starting balance and it compounds alongside your new deposits.

Is this calculator free?

Yes — free, browser-based, and no account needed.

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