Project future value of present sum + annuity.
Future value
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FV of present sum alone
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FV of payments alone
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Your breakdown
Updates live as you type| Component | Future value |
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The single most useful formula in finance
Future value answers a question that sits underneath almost every financial decision: if I have a sum of money, or a habit of saving, what will it be worth later. It is the engine inside retirement projections, loan math, savings goals, and the valuation of nearly any income stream. This calculator handles the two situations that cover most real life: a lump sum you have today that grows untouched, and a stream of equal payments you add over time. You can model either alone or both together.
The mechanics are pure time value of money. A present sum grows by compounding at the periodic rate. A series of payments grows as an annuity, where each payment compounds for the time remaining until the end. The tool divides your annual rate by the payment frequency and counts the total number of periods, then applies the standard formulas. No taxes, no inflation, no fees, just the arithmetic of compounding.
Splitting the answer into two clean pieces
One thing this tool does well is separate the result into the growth of your starting balance and the growth of your contributions. That separation is genuinely instructive, because it shows where your future wealth actually comes from. For a young saver adding money monthly, the contributions usually dominate. For someone who already holds a large balance, the lump sum carries most of the weight. Seeing the two side by side tells you whether your priority should be saving more or simply leaving what you have alone to compound.
$10,000 today plus $500 a month for 20 years
Take the default inputs: a $10,000 present value, $500 added every month, a 7% annual rate compounded monthly, over 20 years. The calculator splits and totals it like this.
You contributed $10,000 up front plus $120,000 across 240 monthly payments, for $130,000 of your own money in. It grew to $300,851. That means roughly $170,851 is compounding, more than the total you put in. The payments alone become $260,463, swamping the $40,387 from the starting balance, which is the textbook lesson that consistent contributions, given enough time, outweigh the head start.
Watching contributions overtake the lump sum
The chart breaks the $300,851 into its three parts: the money you actually contributed, the growth on your lump sum, and the growth on your payments.
Ordinary annuity, and why the timing matters
This is a detail worth being precise about. The calculator treats the payment stream as an ordinary annuity, where each payment lands at the end of its period. That is the right model for most savings and loan situations. There is a second flavor, the annuity due, where payments arrive at the start of each period, as with rent or many insurance premiums. An annuity due earns one extra period of compounding on every payment, so its future value is higher by a factor of one plus the periodic rate. In this example that would add a little over half a percent, lifting the payment piece by roughly $1,500. If your real world payments occur at the beginning of the period, the figure here is slightly conservative.
Who this serves and what it deliberately ignores
This tool fits anyone running a quick savings projection, a student learning time value of money, or someone sanity checking a more elaborate retirement model. It is the clean, assumption free core that bigger calculators build on top of. The honest limitations are all about what it leaves out. It uses a single fixed rate, while real returns vary year to year. It does not adjust for inflation, so $300,851 in 20 years buys less than $300,851 today; at 3% inflation it is worth closer to $166,000 in today's purchasing power. And it ignores taxes and investment fees, both of which drag on real outcomes. Use it to understand the shape of compounding, then layer in inflation and taxes for a planning decision.
Does compounding more often than monthly change the result much?
Less than people expect. Moving from annual to monthly compounding at the same nominal rate adds a noticeable bump, but going from monthly to daily adds very little. The big jump is from annual to monthly. Beyond that, the effective annual rate creeps up only marginally, which is why most savings projections stop at monthly compounding.
What rate should I plug in for a stock portfolio?
A common long run assumption for a diversified US stock portfolio is around 7% after inflation, or roughly 10% before inflation, based on historical averages. If you want your future value expressed in today's dollars, use the real rate near 7% and treat the result as purchasing power. If you want a nominal dollar figure, use the higher rate and remember those dollars will buy less.
How is future value related to present value?
They are inverses. Future value compounds a known sum forward in time, while present value discounts a known future sum back to today. If you want to know what a future goal is worth in today's dollars, or what a future payment stream is worth now, you run the present value calculation instead.