Car Affordability Calculator

How this is calculated

Four steps, in the order the money actually leaves. Work out what is left for a payment, turn that into a principal, add what you bring to the deal, then take the tax and the fees back off to reach a price you can shop with.

payment available  = monthly budget − insurance − fuel − upkeep

most you can finance
                   P = M × (1 − (1 + r)⁻ⁿ) ÷ r
                     M = payment available
                     r = APR ÷ 100 ÷ 12
                     n = the term, in months

net trade-in       = trade-in allowance − what you still owe on it
most out the door  = P + cash down + net trade-in

cash price of car  = (most out the door − fees) ÷ (1 + tax rate)

The first formula is the standard amortization identity solved for the principal instead of the payment — the same arithmetic the Auto Loan Payment Calculator runs forwards. Because they are exact inverses, financing the figure this page gives you, on the same rate and term, produces exactly the payment it started from. Our checks assert that round trip rather than trusting it.

Why the last line is a division

The fees are a flat amount and are not taxed, so they come off first, with a subtraction. The sales tax cannot come off the same way: it is charged on the price of the car, and the price is the thing being solved for. If the budget supports $31,090 out the door, $650 of that is fees, leaving $30,440 for the car and its tax. At a 7% rate the car is not $30,440 less 7%, which would be $28,309 — it is $30,440 ÷ 1.07, which is $28,448. The gap is small at this rate and grows with it, and it is the kind of error that looks like arithmetic rather than like a mistake, which is why the order of those two operations is printed above rather than left implicit.

Why the price is below what you can finance

Because the lender is not financing a car. It is financing the car plus the sales tax, the title, the registration and the dealer fees — the construction the Truth in Lending Act sets out in Regulation Z, 12 CFR § 1026.18(b), which defines the amount financed as the cash price less any downpayment, plus “any other amounts that are financed by the creditor and are not part of the finance charge.” Sales tax and fees are that second step. Run forwards, as on our loan page, that is why a payment comes out higher than people expect. Run backwards, as here, it is why the car does.

Why insurance, fuel and upkeep are fields and not assumptions

Because they are the larger of the two corrections, and because there is no honest number to put in them on your behalf. What you pay to insure a car depends on the car, your record, your state and your deductible; what you pay to fuel it depends on how far you drive and what you drive. A calculator that assumes any of these has assumed away the part of the answer that varies most. So they are three empty fields — and the two tools that fill the middle one, the Commute Cost Calculator and EV vs. Gas Cost Calculator, are linked from beside it.

Leave all three blank and the tool still works — it simply becomes an affordability calculator that only corrects for tax and fees, and the “if you counted only the payment” block collapses to that. That is a legitimate way to use it. It is just not the whole cost of the drive.

What a payment-only answer costs

The third block of output prices the mistake. It takes the same budget, treats the whole of it as a loan payment, and calls the resulting principal a car price — which is what a payment-only calculator does. On the worked example that is $46,436 against a real $28,448. The $17,988 difference splits exactly two ways: $15,346 is the present value of the insurance, fuel and upkeep you would have been paying anyway, and $2,641 is the tax and the fees. Nothing is apportioned or estimated to reach that split — present value is linear in the payment, so the two parts add to the whole by construction, and our checks assert it.

The Consumer Financial Protection Bureau makes the same point about loan shopping generally: “It's common to focus on the monthly payment, but there are other factors that have more impact on the total costs you'll pay over the life of your loan” . A monthly payment is what a dealership negotiates in, because it is the number that can be moved without changing the price. This page is built to hand you the other one.

A ceiling is not a target

The figure at the top is the most expensive car the budget reaches with nothing left over. That is a useful number to shop against and a poor one to spend to. It also carries one circularity worth naming: it assumes the insurance and fuel figures you entered hold for a car at the price it just computed, and they usually will not — a dearer car generally costs more to insure and more to shoe. If the price comes back well above what you had in mind, re-enter the carrying costs as quotes for a car at that level and run it again. The honest use of this tool is two passes, not one.

What this does not cover

Whether you should spend it. There is no published threshold that makes a car payment affordable or unaffordable without knowing your income, your rent and what you have set aside, so this page does not grade the answer or suggest a budget. The budget is the input; the price is the output.

Also excluded: your approval odds, rate and term — this is not a credit offer; depreciation and what the car will be worth, which is what decides whether a long loan leaves you underwater; registration and property taxes that recur annually in some states, which belong in the upkeep field if they apply to you; add-on products such as extended warranties and gap insurance, which are financed and so belong in the fees field; and how your state taxes a sale — the tax here is applied to the full price, while several states tax the price after the trade-in is deducted. That last one makes this tool slightly conservative where it applies: you could afford a little more car than it says. For a budget, that is the right direction to be wrong in.

Last reviewed: August 2026