Financing, sales tax, leasing math and true cost of ownership.
A car is one of the largest purchases most people make, and the sticker price is only part of the story. This guide covers financing, taxes, leasing and the true cost of ownership — with a calculator for each decision.
When you finance a car, the monthly payment depends on the amount borrowed, the interest rate and the term. Longer terms lower the payment but raise total interest and increase the time you spend underwater (owing more than the car is worth). A useful discipline is to choose the shortest term whose payment you can comfortably afford. The Car Payment Calculator turns price, down payment, rate and term into a monthly payment.
The price you negotiate isn't the price you pay. Sales tax, fees and the effect of a trade-in all change the final number. In most states a trade-in reduces the taxable amount, which can save hundreds, and manufacturer rebates often reduce it too — though rules vary by state. The Car Sales Tax Calculator estimates the tax and your true out-the-door price including trade-in and rebates.
A lease isn't a loan — you're paying for the car's depreciation over the lease term plus a finance charge. The payment is driven by the negotiated price (cap cost), the residual value at lease end, and the money factor (the lease's interest rate; multiply it by 2,400 to approximate an APR). Understanding these levers helps you spot a good lease from a bad one. The Auto Lease Payment Calculator breaks a lease payment into its depreciation and finance parts.
Two cars with the same price can cost very different amounts to own. Fuel, insurance, maintenance, repairs and especially depreciation add up — often more than the loan itself. Expressing everything as a cost per mile makes vehicles comparable and reveals the real budget impact. The Cost Per Mile Calculator sums your annual costs and divides by miles driven to show what each mile actually costs.
Buying usually wins over the long run because you eventually own an asset and stop making payments; leasing offers lower payments and a new car every few years but a perpetual payment. If you drive a lot, buying tends to win (leases penalize high mileage); if you value low payments and always driving something new, leasing can fit. Either way, run the numbers on total cost, not just the monthly figure.
Negotiate the price before discussing financing or trade-in; get pre-approved so you can compare the dealer's rate; factor sales tax and fees into your budget; favor shorter loan terms; and estimate insurance and fuel before you commit. The best deal is the one that's cheapest to own, not just the one with the lowest monthly payment.
From the amount financed, the interest rate and the loan term, using standard amortization.
In most states, yes — the trade-in reduces the taxable amount; a few states tax the full price.
It covers the car's depreciation (price minus residual) plus a finance charge based on the money factor.
Total annual costs — fuel, insurance, maintenance and depreciation — divided by miles driven.
Buying usually costs less long-term and suits high-mileage drivers; leasing offers lower payments and a newer car more often.