InvestmentCalculator helps you estimate the complete return on a rental property and compare it with alternatives such as stocks, bonds, CDs, or savings accounts.
The app is dependency-free. From this directory, run:
python3 -m http.server 4173Then open http://localhost:4173. You can also use npm start if Node is installed.
Financial calculations live in finance.js as pure functions. Run the edge-case and integration tests with:
npm testScenarios are stored only in your browser's local storage. CSV exports are generated locally; Print / PDF uses the browser's print dialog.
The calculator combines four sources of real-estate return:
- Appreciation: The estimated increase or decrease in property value.
- Equity buydown: The mortgage principal paid off over time.
- Net rental income: Rental income remaining after expenses and mortgage payments.
- Estimated tax benefits: Potential value from deductible expenses and depreciation.
These results are combined to show your estimated total return, annualized return, cash flow, and ending wealth.
You can compare a real-estate investment with a traditional compound investment using the same:
- Initial investment
- Additional contributions
- Holding period
- Tax and fee assumptions
The comparison estimates the opportunity cost of choosing one investment over another.
- Enter the property price, down payment, mortgage terms, and purchase date.
- Add expected rental income and operating expenses.
- Enter appreciation, tax, depreciation, and sale assumptions.
- Configure the alternative investment’s expected return and contributions.
- Review the results, charts, and annual projections.
Results update automatically as assumptions change.
The mortgage calculator supports:
- Monthly payments
- Biweekly payments
- Extra monthly payments
- Extra annual payments
- One-time principal payments
- PMI, taxes, insurance, HOA fees, and other costs
An amortization table shows interest, principal reduction, and the remaining loan balance over time.
Expenses may include:
- Property taxes
- Insurance
- HOA fees
- Property management
- Maintenance and repairs
- Vacancy
- Utilities
- Legal and professional fees
- Other recurring costs
Enter expenses as accurately as possible. Small changes can meaningfully affect long-term results.
- Cash flow: Income remaining after expenses and debt payments.
- Principal reduction: Mortgage debt paid off during the holding period.
- Projected equity: Property value minus the remaining mortgage balance.
- Cash-on-cash return: Annual cash flow divided by cash invested.
- Annualized return: Average compounded return over the holding period.
- Opportunity cost: Difference in ending wealth between the investments.
- IRR: Return calculated using the timing of contributions and distributions.
Depending on the installed version, you can:
- Save investment scenarios
- Duplicate scenarios
- Compare multiple deals
- Export assumptions and results as CSV or PDF
Investment results are projections, not guarantees. They depend on assumptions about appreciation, rent, vacancies, expenses, taxes, interest rates, and investment performance.
For a fair comparison, use the same holding period and equivalent cash contributions for both investments.
Tax estimates may include depreciation and eligible expenses described in IRS Publication 527. Eligibility depends on how the property is used and your individual tax circumstances.
This calculator provides estimates for educational purposes only. It does not provide financial, tax, legal, or investment advice. Consult qualified professionals before making an investment decision.