finance calculator

Investment Calculator

Project compound growth, regular contributions, and future value.

Formula Verified by Dr. Elizabeth Vance, PhD

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Initial amount$

Monthly contribution$

Annual return%

Years

Results

Future value

$106,639

Total contributions$70,000

Investment growth$36,639

Months invested120 months

Bookmark this Investment Planner

Save this page to compare conservative and aggressive asset returns, contribution amounts, and investment timelines.

Formula

Investment growth method

Future value = starting amount compounded monthly + each monthly contribution compounded over time

The calculator compounds the starting balance and recurring monthly contributions across the investment term.

Step by step

How the calculation works

1Enter your starting amount, monthly contribution, annual return, and time horizon.
2The calculator compounds growth monthly.
3Results separate total contributions from investment growth.

Example

Investment example

Starting with $10,000 and adding $500 per month for 10 years at a 7% annual return produces a future value above the contribution total because each month compounds over time.

Related guides

Learn more about this calculation

Guide

Portfolio Diversification: A Practical Allocation Guide

Learn how asset allocation, diversification, correlation, costs, and rebalancing work, plus what a portfolio growth calculator can and cannot show.

Guide

Compound Interest: Formula, Examples, and Calculator

Learn how compound interest works, calculate growth with monthly deposits, compare assumptions, and avoid common projection mistakes.

How to understand and use this calculator

Building Wealth: The Power of Systematic Investing

An investment portfolio grows through two primary drivers: capital contributions and market returns. Systematic investing—consistently adding cash month after month—is the most reliable way to scale an investment account.

By investing regularly, you participate in dollar-cost averaging (buying more shares when prices are low and fewer when prices are high), reducing overall portfolio volatility. This tool separates your out-of-pocket contributions from compound market gains, showing you the exact source of your future net worth.

The Math of Market compounding

Investment growth relies on the future value of a recurring annuity. When you invest, the returns earned are reinvested in assets (stocks, bonds, mutual funds) that generate additional dividends, interest, or capital appreciation.

The compound growth rate represents the annualized average return of your portfolio. Over short horizons (1 to 5 years), your net worth is primarily driven by your personal cash contributions. Over long horizons (15 to 30 years), the compounding returns overtake your contributions, generating the majority of the portfolio's total value.

Adjusting for Investment Fees and Expense Ratios

Fees are the silent killer of long-term investment returns. Mutual funds and exchange-traded funds (ETFs) charge an annual Expense Ratio (fee percentage), which is subtracted directly from your returns.

For example, a 1.0% expense ratio may seem small, but over 30 years, it can reduce your ending portfolio value by up to 20% compared to low-cost index funds charging 0.05%. To account for expense ratios or advisory fees, subtract them from your annual interest rate input.

Tax-Deferred vs. Taxable Portfolios

Where you hold your assets determines how they are taxed. Tax-advantaged retirement accounts (like traditional 401ks or IRAs) allow your investments to compound tax-deferred, meaning you pay no taxes on capital gains or dividends until withdrawal. This accelerates growth compared to standard taxable brokerage accounts, where tax drags reduce the annual return rate.

Related concepts

Dollar-Cost Averaging

Consistent investing on a set schedule to reduce average share costs over time.

Expense Ratio

The annual management fee charged by mutual funds or ETFs, reducing net returns.

Compound Return

The rate of return that accounts for reinvesting previous earnings over consecutive years.

Frequently Asked Questions

How do you calculate return on investment?+

Return on investment (ROI) is calculated by dividing the net profit by the initial cost of the investment. For compounding portfolios with ongoing contributions, this investment calculator uses the future value formula of an ordinary annuity to project growth over time.

How can I calculate how much my investments will grow?+

You can project your investment growth by inputting your starting balance, recurring monthly or annual contributions, annual interest rate, and years to grow. The calculator computes the future value, itemizing your principal versus compound returns.

Is the annual return rate guaranteed?+

No. The annual return is an assumption used for long-term planning. Real market returns fluctuate significantly year-to-year due to market volatility.

What is dollar-cost averaging?+

Dollar-cost averaging is the practice of investing a fixed dollar amount on a regular schedule, buying more shares when prices are low and fewer when prices are high to average out costs.

How do fees and expense ratios affect returns?+

Expense ratios are annual fees charged by funds. They are deducted directly from your returns, reducing the principal base and compounding speed over time.

What is the difference between stocks and bonds?+

Stocks represent ownership in a company and offer higher growth potential with higher volatility. Bonds are loans to corporations or governments, offering fixed interest payments with lower risk.

Does this calculator deduct taxes?+

No. This calculator projects pre-tax growth. To estimate after-tax growth, adjust your expected annual return rate downward to account for your tax bracket.

What is a tax-advantaged account?+

Tax-advantaged accounts (like 401ks, IRAs, or HSAs) offer tax benefits, allowing your investments to grow tax-deferred or tax-free, which accelerates compounding.

How much should I invest monthly?+

A standard benchmark is to invest 15% of your gross household income for retirement, adjusting upwards or downwards based on your age and target financial goals.

What is portfolio rebalancing?+

Rebalancing is the process of adjusting the weights of your asset classes (e.g., selling stocks and buying bonds) to restore your original target risk level.

What does "nominal" vs "real" return mean?+

Nominal return is the raw rate of return on your investment. Real return is the return adjusted for inflation, representing the actual increase in your purchasing power.

What is the standard historical return of the stock market?+

Historically, the US stock market (S&P 500) has averaged an annual return of about 10% before inflation, and about 7% when adjusted for historical inflation.

How to understand and use this calculator

Building Wealth: The Power of Systematic Investing

The Math of Market compounding

Adjusting for Investment Fees and Expense Ratios

Tax-Deferred vs. Taxable Portfolios

Related concepts

Dollar-Cost Averaging

Consistent investing on a set schedule to reduce average share costs over time.

Expense Ratio

The annual management fee charged by mutual funds or ETFs, reducing net returns.

Compound Return

The rate of return that accounts for reinvesting previous earnings over consecutive years.

Frequently Asked Questions

How do you calculate return on investment?+

How can I calculate how much my investments will grow?+

Is the annual return rate guaranteed?+

No. The annual return is an assumption used for long-term planning. Real market returns fluctuate significantly year-to-year due to market volatility.

What is dollar-cost averaging?+

Dollar-cost averaging is the practice of investing a fixed dollar amount on a regular schedule, buying more shares when prices are low and fewer when prices are high to average out costs.

How do fees and expense ratios affect returns?+

Expense ratios are annual fees charged by funds. They are deducted directly from your returns, reducing the principal base and compounding speed over time.

What is the difference between stocks and bonds?+

Stocks represent ownership in a company and offer higher growth potential with higher volatility. Bonds are loans to corporations or governments, offering fixed interest payments with lower risk.

Does this calculator deduct taxes?+

No. This calculator projects pre-tax growth. To estimate after-tax growth, adjust your expected annual return rate downward to account for your tax bracket.

What is a tax-advantaged account?+

Tax-advantaged accounts (like 401ks, IRAs, or HSAs) offer tax benefits, allowing your investments to grow tax-deferred or tax-free, which accelerates compounding.

How much should I invest monthly?+

A standard benchmark is to invest 15% of your gross household income for retirement, adjusting upwards or downwards based on your age and target financial goals.

What is portfolio rebalancing?+

Rebalancing is the process of adjusting the weights of your asset classes (e.g., selling stocks and buying bonds) to restore your original target risk level.

What does "nominal" vs "real" return mean?+

Nominal return is the raw rate of return on your investment. Real return is the return adjusted for inflation, representing the actual increase in your purchasing power.

What is the standard historical return of the stock market?+

Historically, the US stock market (S&P 500) has averaged an annual return of about 10% before inflation, and about 7% when adjusted for historical inflation.

Investment Calculator

Inputs

Results

Bookmark this Investment Planner

Investment growth method

How the calculation works

Investment example

Learn more about this calculation

Portfolio Diversification: A Practical Allocation Guide

Compound Interest: Formula, Examples, and Calculator

Investment Calculator

Inputs

Results

Bookmark this Investment Planner

Key output metrics

Contributions vs growth

Portfolio growth timeline

How to understand and use this calculator

Building Wealth: The Power of Systematic Investing

The Math of Market compounding

Adjusting for Investment Fees and Expense Ratios

Tax-Deferred vs. Taxable Portfolios

Related concepts

Frequently Asked Questions

Investment growth method

How the calculation works

Investment example

Learn more about this calculation

Portfolio Diversification: A Practical Allocation Guide

Compound Interest: Formula, Examples, and Calculator

Key output metrics

Contributions vs growth

Portfolio growth timeline

How to understand and use this calculator

Building Wealth: The Power of Systematic Investing

The Math of Market compounding

Adjusting for Investment Fees and Expense Ratios

Tax-Deferred vs. Taxable Portfolios

Related concepts

Frequently Asked Questions