Lease vs. Buy: Which Inputs Actually Matter

Comparing a lease payment against a loan payment alone is comparing the wrong numbers — buying leaves you with an asset a lease never does, so a fair comparison has to account for that. This guide walks through the pieces that actually decide whether leasing or buying wins, and the calculators that handle each one.

First, Know What You’re Financing: The Loan Itself

The Auto Loan Calculator works out the actual monthly payment on a purchase — vehicle price minus down payment and trade-in value, plus sales tax, financed at the loan’s rate and term. A down payment and a trade-in both reduce what’s financed, but in most US states only the trade-in reduces what sales tax is calculated on, since a down payment is already-taxed money. If a trade-in is worth less than what’s still owed on it (being “underwater”), that shortfall doesn’t disappear — it gets rolled into the new loan, quietly increasing both the amount financed and the total interest paid.

Practical takeaway: a longer loan term lowers the monthly payment but usually increases total interest paid overall — compare total interest across term lengths, not just the payment, before stretching a term purely to fit a budget.

Then, Know What a Lease Payment Is Actually Built From

The Auto Lease Calculator derives a lease payment from two separate charges: a depreciation fee (the vehicle’s expected value loss over the lease term) and a finance fee (based on the lease’s “money factor,” a standard conversion from APR). Unlike a loan, a lease payment never covers the vehicle’s full price — only the portion of value it’s expected to lose while you’re driving it, plus financing. A capitalized cost reduction (a lease’s version of a down payment) lowers the payment the same way a loan down payment does, but doesn’t build any ownership stake, since the vehicle isn’t owned at the end of a standard lease.

Practical takeaway: even a few percentage points of difference in the assumed residual value between two vehicles or offers can shift the payment noticeably, since the depreciation fee is the vehicle’s price minus its residual value spread over the term — it’s worth asking what residual value a quote is actually using rather than treating it as fixed.

The Comparison That Actually Answers the Question

The Lease vs. Buy Calculator is the one built to answer “which wins,” and it deliberately compares net cost, not monthly payment — because buying leaves you with equity (resale value minus any remaining loan balance) that leasing never does. A lease’s lower monthly payment can look like the obvious winner, but ignoring the equity buying builds is exactly the comparison mistake this calculator exists to correct.

Practical takeaway: the comparison period matters as much as any single input — a short window favors leasing simply because it doesn’t capture the payment-free years of ownership that come after a loan is paid off, so match the comparison period to how long the vehicle would actually be kept either way, not an arbitrary number of months.

Putting It Together

Work out Auto Loan Calculator‘s real monthly payment for the buying side and

Auto Lease Calculator

‘s real monthly payment for the leasing side — rather than a dealer’s advertised numbers, which can bundle assumptions that don’t match the actual deal — then feed those figures into Lease vs. Buy Calculator along with a researched (not guessed) resale-value percentage for the specific vehicle. A vehicle’s actual depreciation rate is the single biggest driver of which option wins: vehicles that hold their value well tend to favor buying, since there’s more resale equity to offset the loan, while fast-depreciating vehicles often favor leasing. Mileage limits and wear-and-tear charges are real costs a lease adds that these net-cost numbers alone don’t capture — a driver who regularly exceeds a lease’s mileage allowance may find buying meaningfully cheaper in practice than the calculator’s own comparison suggests.