How much car can you afford?

Start from income, not from inventory

The market’s numbers first, because they’re sobering: in Q1 2026 the average new-car payment hit $770 a month, the average used payment $531, on average loans of about $43,925 and $27,070 at average APRs of 6.39% new and roughly 11.43% used (Experian). Those are averages of what people do, not of what people can comfortably afford. Anchor to your income instead.

The 20/4/10 guideline

A widely used rule of thumb: put about 20% down, borrow for no more than 4 years, and keep payment plus insurance under 10% of gross monthly income. It’s not scripture, it’s a forcing function. Each leg kills a specific failure mode: the down payment keeps you from owing more than the car’s worth; the short term caps total interest; the 10% line protects the rest of your life from your car.

Applied honestly:

Notice the uncomfortable implication: the average American new-car payment of $770, before insurance, requires roughly a six-figure income to fit this guideline. Most people buying average new cars are outside it. That’s not judgment; it’s the reason so many people feel owned by their car payment.

The math nobody runs at the dealership

A longer loan is the standard tool for making an unaffordable car “affordable.” Illustration at the Q1 2026 average new rate of 6.39%: borrow $35,000 for 48 months and pay about $828/month and ~$4,750 in interest; stretch it to 84 months and the payment falls to about $518, while total interest climbs near-double to ~$8,500, and you spend years owing more than the car is worth. The payment shrank; the cost grew. That’s the whole trick, and it’s why the 4 in 20/4/10 exists.

Costs that aren’t the payment

Insurance varies enough by age, record, and model to swing a decision by itself, quote it on the specific car before you commit, not after. Fuel is a knowable number from your commute and the EPA rating. Maintenance, tires, registration, and depreciation are quieter but real. A useful summary: the payment is usually only 60 to 70% of what a car actually costs to run.

Where to flex the rule, honestly

Guidelines bend for context. Low fixed housing costs, a paid-off second car, or a genuine business use case can justify more; existing debt, variable income, or thin savings argue for less than 10%. Two flexes that are usually self-deception, though: assuming a future raise, and stretching the term “temporarily.” If the numbers only work at 72 to 84 months, the honest reading is that this car doesn’t fit yet, the alternatives are a bigger down payment, a cheaper (often lightly used) car, or waiting.

Next steps

Compute your 10% line. Get insurance quotes on your two or three candidate cars. Get pre-approved by a bank or credit union so you know your real APR, not the average. Then shop cars whose out-the-door price fits the math, with a payment you’ll barely notice, which is the entire point.