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Finance & LoansGenerated accuracy model review: 2026-05-06
Auto Lease 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
- A lease payment has two parts: 1. **Depreciation**: (Net Cap Cost - Residual) / Term 2. **Finance Charge**: (Net Cap Cost + Residual) * Money Factor Total Monthly = Depreciation + Finance + Tax.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- MSRP / Sticker: $35,000
- Negotiated Price: $33,000
- Residual Value: 58%
- Lease Term: 36
- Money Factor: 0
- Sales Tax: 7%
Expected outputs
- Estimated Lease Payment: $520.05
- Total Lease Cost: $18,721.79
- Equivalent APR: 6.00%
Known limitations
- Does not include dealer documentation fees or registration fees, which are usually paid upfront.
Assumptions
- Inputs are interpreted exactly as entered in the calculator form.
- The calculation runs locally in the browser using the current checked-in calculator definition.
Unit handling
- MSRP / Sticker accepts values in $.
- Negotiated Price accepts values in $.
- Residual Value accepts values in %.
- Lease Term accepts numeric values.
- Money Factor accepts numeric values.
- Sales Tax accepts values in %.
- Estimated Lease Payment is displayed as currency.
- Total Lease Cost is displayed as currency.
- Equivalent APR is displayed as a percentage.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
- Currency outputs are displayed with standard US dollar formatting.
- Percent outputs are displayed with two decimal places.
- Input precision follows configured step values where provided.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current auto-lease-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Auto Lease Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.