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Procurement & VendorsGenerated accuracy model review: 2026-05-06
Buy vs 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
- Buy total cost = purchase price + annual maintenance cost * years - residual value. Lease total cost = monthly lease payment * 12 * years + lease fees. Buy savings vs lease = lease total cost - buy total cost.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Purchase Price: $75,000
- Annual Maintenance Cost: 5,000 $/year
- Residual or Resale Value: $20,000
- Monthly Lease Payment: 2,400 $/mo
- Lease Fees: $3,000
- Analysis Period: 3 years
Expected outputs
- Buy Savings vs Lease: $19,400.00
- Buy Total Cost: $70,000.00
- Lease Total Cost: $89,400.00
- Lower-Cost Option: Buy
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, discounts, costs, volumes, terms, and rates are user-entered assumptions.
- Calculations are deterministic and run locally in the browser without uploading procurement data.
- Results are planning estimates and do not replace legal, accounting, tax, security, operational, or procurement review.
Unit handling
- Purchase Price accepts values in $.
- Annual Maintenance Cost accepts values in $/year.
- Residual or Resale Value accepts values in $.
- Monthly Lease Payment accepts values in $/mo.
- Lease Fees accepts values in $.
- Analysis Period accepts values in years.
- Buy Savings vs Lease is displayed as currency.
- Buy Total Cost is displayed as currency.
- Lease Total Cost 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 buy-vs-lease-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Buy vs Lease Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.