Lease vs Buy Calculator accuracy and testing

Formula source

• Lease total = due at signing + payments + end fees. Buy net cost = down payment + payments + fees - resale value.

Test cases

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, fees, rates, and vehicle assumptions are user-entered.
• Calculations run locally in your browser and are not stored by Calwarden.
• This is planning math, not financial, tax, insurance, legal, or mechanical advice.

Unit handling

• Comparison Term accepts values in months.
• Lease Due at Signing accepts values in $.
• Lease Payment accepts values in $/mo.
• Lease End Fees accepts values in $.
• Buy Down Payment accepts values in $.
• Buy Loan Payment accepts values in $/mo.
• Buy Fees/Taxes accepts values in $.
• Estimated Resale Value accepts values in $.
• Lease 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

Change log