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Home & UtilitiesGenerated accuracy model review: 2026-05-06
Rent vs Buy with Maintenance Calculator accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- Rent total sums rent with growth. Buy net cost includes down payment, ownership costs, transaction costs, and mortgage balance offset by estimated home value.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Monthly Rent: 2,300 $/mo
- Rent Growth: 3 %/yr
- Home Price: $420,000
- Down Payment: 10%
- Mortgage Rate: 6.5%
- Loan Term: 30 years
- Property Tax: 1.2 %/yr
- Insurance: 160 $/mo
- HOA Dues: 150 $/mo
- Maintenance: 1 %/yr
- Home Appreciation: 3 %/yr
- Buy/Sell Costs: 8%
- Analysis Period: 7 years
Expected outputs
- Lower Estimated Cost: Buy is lower
- Rent Total Cost: $211,483.96
- Buy Net Cost: $192,240.62
- Estimated Difference: $19,243.34
Known limitations
- This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
- Use the result as a planning estimate unless the calculator page states a stricter purpose.
Assumptions
- All prices, rates, taxes, and usage values are entered by the user.
- Calculations run locally in your browser and are not stored by Calwarden.
- This is planning math, not financial, tax, engineering, or legal advice.
Unit handling
- Monthly Rent accepts values in $/mo.
- Rent Growth accepts values in %/yr.
- Home Price accepts values in $.
- Down Payment accepts values in %.
- Mortgage Rate accepts values in %.
- Loan Term accepts values in years.
- Property Tax accepts values in %/yr.
- Insurance accepts values in $/mo.
- HOA Dues accepts values in $/mo.
- Maintenance accepts values in %/yr.
- Home Appreciation accepts values in %/yr.
- Buy/Sell Costs accepts values in %.
- Analysis Period accepts values in years.
- Rent Total Cost is displayed as currency.
- Buy Net Cost is displayed as currency.
- Estimated Difference is displayed as currency.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
- Currency outputs are displayed with standard US dollar formatting.
- Input precision follows configured step values where provided.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current rent-vs-buy-with-maintenance-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Rent vs Buy with Maintenance Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.