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Hazuu Tools

Investment Calculator

Calculate investment growth with compound interest, monthly contributions, and inflation adjustment.

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Investment Details

Initial Investment
$
Monthly Contribution
$
Annual Return Rate (%)
%
Investment Length (years)
Compound Frequency
Inflation Rate (%)
%
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Investment Summary

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Enter your investment details and click Calculate
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About Investment Calculator

The Investment Calculator projects the future growth of a portfolio by combining compound interest on a lump-sum principal with the compounding effect of regular monthly contributions. You enter an initial investment, a monthly top-up amount, an expected annual return rate, a time horizon in years, and a compounding frequency (annually, semi-annually, quarterly, monthly, or daily). The tool then computes the precise future value using the standard annuity formula, so every dollar you add each month earns its own compound interest from the moment it lands.

The calculator is built for moments when you need a quick, number-backed sanity check: How much will $5,000 invested today plus $200 a month be worth in 20 years at 7%? How much does changing from annual to monthly compounding actually add? How does a 1% difference in return rate change the outcome over 30 years? It gives you exact figures for future value, total contributions, interest earned, ROI percentage, and a full line-by-line breakdown table so you can see exactly where each dollar comes from.

Unlike the sibling Interest Rate Calculator — which works backwards to find the rate needed to reach a target — this tool works forward from inputs you already know or can estimate. All arithmetic runs in your browser; nothing is uploaded, stored, or logged. There are no accounts to create, no limits on how many scenarios you can run, and no cost.

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Key Features

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Monthly contribution compounding

Each monthly deposit is treated as a separate annuity payment that earns compound interest from the moment it is added, not just at year end — so the math matches how index funds and brokerage accounts actually accumulate.

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Five compounding frequencies

Switch between annually, semi-annually, quarterly, monthly, and daily compounding to see the real difference in final value, especially relevant for savings accounts and bonds that compound more frequently than once a year.

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Inflation-adjusted future value

The calculator deflates the nominal future value by your chosen inflation rate so you can see what your projected balance is worth in today's dollars — critical for retirement planning where purchasing power matters more than raw dollar amounts.

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Preset rate buttons for common benchmarks

One-click presets for 4%, 6%, 7%, 8%, 10%, and 12% let you compare conservative bond returns against historical stock market averages without retyping the same numbers repeatedly.

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Full investment breakdown table

Results include a line-by-line table showing initial investment, monthly contributions total, total contributions, interest earned, and final future value — so you can see exactly how much of your portfolio came from your own money versus market growth.

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ROI percentage alongside dollar figures

Return on investment is shown as a percentage (total interest divided by total contributions) alongside the dollar amounts, giving you a normalized benchmark to compare scenarios with different starting principals.

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How to Use

01

Set Initial Amount

Enter the lump sum you plan to invest upfront. This is your starting principal that will begin earning compound interest immediately.

02

Add Contributions

Specify how much you will contribute each month. Regular contributions significantly boost long-term growth through dollar-cost averaging and additional compounding.

03

Choose Rate & Length

Set your expected annual return rate using the preset buttons or a custom value, select the compounding frequency, and enter your investment time horizon in years. Optionally adjust the inflation rate.

04

Calculate

Click Calculate to see your projected future value, total contributions, interest earned, inflation-adjusted value, ROI percentage, and a complete investment breakdown table.

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Example

A $5,000 lump sum plus $200 per month at 7% annual return compounded monthly for 20 years, with a 2.5% inflation rate.

Inputs
Initial investment:   $5,000.00
Monthly contribution: $200.00
Annual return rate:   7%
Investment length:    20 years
Compound frequency:   Monthly
Inflation rate:       2.5%
Results
Future Value:                  $124,379.03
Total Contributions:            $53,000.00
Total Interest Earned:          $71,379.03
Future Value (Inflation-Adj.):  $75,904.91
Return on Investment (ROI):     134.68%
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Common Use Cases

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    Retirement portfolio projection

    Model how a current 401(k) or IRA balance grows alongside monthly contributions over 20 or 30 years, adjusting the return rate to reflect your actual fund allocation mix. The inflation-adjusted result shows whether your projected balance will actually meet your spending needs in real terms.

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    Comparing index fund vs. bond allocation

    Run the same contribution schedule at 10% (historical equities average) and then at 4% (bond-like return) to quantify the long-run cost of a more conservative allocation — a specific question this tool answers that a loan or mortgage calculator cannot.

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    Evaluating the impact of starting early

    Compare two scenarios: starting with $0 at age 25 versus $10,000 at age 35, both contributing $300 a month at 7%. The side-by-side future values make the cost of delay concrete rather than abstract.

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    Choosing between lump-sum and regular investing

    Enter a lump-sum amount with zero monthly contributions, then compare to a scenario with a smaller initial amount but higher monthly deposits. This answers the practical question of whether to invest a windfall all at once or spread it out.

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    Setting a savings target to reach a specific goal

    Work backwards by adjusting monthly contributions until the projected future value matches a target (home down payment, education fund, early retirement number). Because the breakdown table shows contributions vs. interest, you can see how much of the target you are funding yourself versus relying on growth.

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Frequently Asked Questions

What is compound interest and how does it help my investments? expand_more
Compound interest means you earn interest not only on your original investment but also on the interest that has already been added. Over time this creates a snowball effect where your money grows exponentially. The longer you stay invested, the more powerful compounding becomes, which is why starting early is one of the most effective investment strategies.
How do monthly contributions affect my investment growth? expand_more
Monthly contributions add new capital to your portfolio on a regular basis. Each contribution begins earning compound interest from the moment it is added, which accelerates your overall growth. Even small monthly amounts can make a significant difference over long time periods due to the compounding effect on each successive contribution.
Why does the calculator include an inflation adjustment? expand_more
Inflation reduces the purchasing power of money over time. A dollar today buys more than a dollar ten years from now. The inflation-adjusted future value shows what your investment will be worth in today's dollars, giving you a more realistic picture of your actual wealth growth and helping you set appropriate savings targets.
What does Return on Investment (ROI) mean in this calculator? expand_more
ROI is calculated as the total interest earned divided by your total contributions, expressed as a percentage. It tells you how much profit your investment generated relative to the money you put in. A higher ROI indicates more efficient growth, though it is influenced by the return rate, time horizon, and compounding frequency you select.
How does compounding frequency affect my returns? expand_more
Compounding frequency determines how often earned interest is added back to your balance. More frequent compounding — such as monthly or daily versus annually — means interest is reinvested sooner and begins earning its own interest faster. At the same nominal annual rate, daily compounding will produce a slightly higher final value than annual compounding over the same period.
How is this Investment Calculator different from the Interest Rate Calculator? expand_more
The Investment Calculator works forward: you provide principal, contributions, rate, and time, and it tells you the resulting future value. The Interest Rate Calculator works backward: you provide a starting amount, a target amount, and a time period, and it solves for the annual return rate you would need to achieve that goal. Use this tool when you know your inputs and want to see the outcome; use the Interest Rate Calculator when you know your target and need to find the required rate.
How is this different from the Loan Calculator or Mortgage Calculator? expand_more
Loan and mortgage calculators model debt repayment — they start with a borrowed balance and calculate how periodic payments reduce principal while interest accrues against you. This Investment Calculator models wealth accumulation — it starts with capital you own and calculates how it grows as interest compounds in your favor. The math uses the same annuity formula but in the opposite direction.
Is my financial data sent to any server? expand_more
No. Every calculation runs entirely in your browser using JavaScript. No numbers you enter are transmitted, stored, or logged anywhere. The page works fully offline once loaded, so your financial scenarios remain completely private.