Does this calculator include taxes or inflation?

No. All results are in pre-tax nominal dollars. To approximate after-tax or inflation-adjusted outcomes, you would need to adjust your return assumptions or apply separate tax and inflation models.

Can I model irregular deposits or changing contribution levels?

This version assumes a fixed monthly contribution. For irregular or step-up contributions, you can run multiple scenarios or use more detailed planning tools alongside this estimate.

How should I choose an annual return assumption?

Base your assumption on your asset mix and risk tolerance, and err on the conservative side for planning. Many long-term stock-heavy portfolios are modeled in the 5–7% range before inflation, but past performance does not guarantee future results.

finance calculator

Future Value / Annuity Estimation

Estimate the future value of steady contributions over time, plus your starting balance, at a given annual return.

Results

Future value: $346,497
Total contributions: $150,000
Growth/interest earned: $196,497

Overview

Regular contributions plus compounding are the backbone of long-term investing. This future value / annuity estimation calculator lets you combine a starting balance with steady monthly contributions and an assumed return to see how your savings could grow over time and how much of the final amount is your own contributions versus investment growth.

In practical terms, this is the math behind retirement accounts, college savings plans, and any “set it and forget it” investing habit where you put money in every month and let time do the heavy lifting. Instead of guessing what a $200 or $500 monthly contribution might turn into decades from now, you can plug in a contribution, time horizon, and return assumption and immediately see a projected future value broken out into contributions vs. growth.

The calculator treats your existing balance as a lump sum and your ongoing deposits as an annuity—two separate engines of growth that work together. That makes it easy to answer questions like “What happens if I increase my contribution by $100?” or “How much difference does an extra five years of saving make?” without building your own spreadsheet or learning financial calculator keystrokes.

How to use this calculator

Enter your current starting balance (if any) that you plan to keep invested during the projection period.
Enter the amount you plan to contribute each month going forward.
Set your assumed annual rate of return and the number of years you want to project.
We convert the annual return to a monthly rate, apply it to both the starting balance and the stream of monthly contributions, and calculate the total future value.
Review the future value, total contributions, and the growth/interest portion to see how much compounding is doing for you.
Adjust contributions, time horizon, or assumed return to explore different savings and investing scenarios.

Inputs explained

Starting balance: The amount of money you already have saved or invested at the beginning of the projection. You can leave this at 0 if you’re starting from scratch.
Monthly contribution: The fixed amount you plan to add each month to your investment or savings account. The calculator assumes you make this contribution consistently every month for the full term.
Annual return (%): Your assumed average annual rate of return before taxes, expressed as a percentage. We convert this to a monthly rate for compounding. Use conservative numbers if you want a safer estimate.
Years: How many years you plan to keep contributing and investing. Longer horizons give compounding more time to work, often producing much larger growth.

Outputs explained

Future value: The projected account value at the end of the chosen term, combining the grown starting balance and all compounded monthly contributions.
Total contributions: The sum of your starting balance plus every monthly contribution made over the projection period. This is the amount you directly put in before growth.
Growth/interest earned: The difference between the future value and your total contributions. This shows how much of the final balance comes from investment returns rather than out-of-pocket deposits.

How it works

We convert your annual return into an effective monthly rate, since contributions and compounding are treated as monthly.

We grow your starting balance forward for the chosen number of years using monthly compounding at that monthly rate.

We treat each monthly contribution as part of a level “annuity” of deposits and apply the standard future value of an annuity formula to see how much those contributions grow over time.

We add the grown starting balance and the compounded value of all contributions to get the total future value.

We also sum all contributions (starting balance plus monthly deposits) and subtract that sum from the future value to compute the growth or interest earned.

Formula

Monthly rate r = (1 + Annual return)^(1/12) − 1\nFuture value of starting balance = Starting balance × (1 + r)^(12 × Years)\nFuture value of contributions ≈ Monthly contribution × [((1 + r)^(12 × Years) − 1) ÷ r]\nTotal future value = FV(starting balance) + FV(contributions)\nTotal contributions = Starting balance + (Monthly contribution × 12 × Years)\nGrowth/interest earned = Future value − Total contributions

When to use it

Estimating how a combination of an existing balance and new savings might grow for retirement, college, or other long-term goals.
Comparing different monthly contribution levels to see what is required to reach a target future balance.
Demonstrating the power of compounding in a savings or investing workshop or client conversation.
Running rough projections for recurring contributions into brokerage, IRA, 401(k), HSA, or other investment accounts.
Exploring how starting early versus starting later affects the role of compounding by holding contributions constant and changing the number of years.
Testing whether a current savings plan looks on track for a goal amount by backing into the gap between projected value and your target.

Tips & cautions

Test multiple return assumptions—such as conservative, base case, and optimistic scenarios—to avoid relying on a single optimistic number.
If you contribute on a different schedule (biweekly or annually), convert your contributions to an equivalent monthly amount for this calculator or run separate scenarios.
Remember this is a nominal projection: it does not adjust for inflation, so the real purchasing power of the future value will be lower than the headline number.
Revisit your projections annually or after major life changes to keep contribution levels aligned with your goals.
Focus on the knobs you can control—contribution size, consistency, and time horizon—rather than trying to fine-tune the return assumption to the decimal.
Use the growth/interest breakdown to motivate saving: seeing how much of the final balance comes from compounding alone often makes it easier to stick with a plan during boring or volatile markets.
Assumes constant monthly contributions and a constant average return; real-world contributions and returns often vary from month to month.
Does not handle irregular deposits, withdrawals, fees, or trading costs that can affect actual results.
Ignores taxes and inflation, so the figures are in pre-tax nominal dollars.
Uses a simplified model and should not be treated as a precise forecast or guarantee of future performance.

Worked examples

Starting from zero with monthly contributions

Set starting balance to $0, monthly contribution to $500, annual return to 6%, and years to 25.
The calculator projects the future value of those contributions and their compounded growth over 25 years.
Interpretation: compare the total contributions to the future value to see how much of the final balance comes from compounding.

Existing balance plus new savings

Set starting balance to $50,000, monthly contribution to $300, annual return to 5%, and years to 20.
Review the future value, total contributions, and growth to see how an existing nest egg grows when combined with continued savings.
Interpretation: this can help you decide whether current contributions are sufficient for your long-term goals or if adjustments are needed.

Dialing contributions to hit a rough target

Suppose you want roughly $250,000 in 18 years for a college or early-retirement goal.
Enter a starting balance (if any), pick a conservative return assumption, and try an initial monthly contribution.
Adjust the monthly contribution up or down until the projected future value is in the ballpark of your target, then use that contribution level as a planning reference.

Deep dive

Estimate the future value of a starting balance plus monthly contributions with this annuity-style growth calculator that breaks out total contributions and growth earned.

Enter starting balance, monthly contribution, years, and return rate to see how your savings or investments could compound over time.

Useful for retirement, college, and general investing plans where steady contributions and compounding drive long-term growth.

Ideal for quick what-if scenarios—such as increasing contributions, changing time horizons, or testing different return assumptions—without building a full financial model.

FAQs

Does this calculator include taxes or inflation?: No. All results are in pre-tax nominal dollars. To approximate after-tax or inflation-adjusted outcomes, you would need to adjust your return assumptions or apply separate tax and inflation models.
Can I model irregular deposits or changing contribution levels?: This version assumes a fixed monthly contribution. For irregular or step-up contributions, you can run multiple scenarios or use more detailed planning tools alongside this estimate.
How should I choose an annual return assumption?: Base your assumption on your asset mix and risk tolerance, and err on the conservative side for planning. Many long-term stock-heavy portfolios are modeled in the 5–7% range before inflation, but past performance does not guarantee future results.

Related calculators

finance

Tuition Savings Calculator

Project future college costs with inflation and find the monthly contribution needed to reach that goal by the time college starts.

finance

Updated Retirement Calculator

Project retirement savings growth with contributions, then combine a withdrawal rate with pension and Social Security to estimate annual retirement income.

finance

Wealth Calculator (Millionaire Next Door)

Benchmark your net worth using the classic Millionaire Next Door expected wealth formula (age × income ÷ 10) and see your gap.

This future value / annuity estimation calculator uses a simplified compound-growth model and is for educational and planning purposes only. It does not account for taxes, fees, inflation, or market volatility, and it is not a guarantee of performance or personalized investment advice. Consider working with a qualified financial professional when making long-term savings and investment decisions.