How Much Car Can I Afford?

The Short Answer: Use the 20/4/10 Rule

The most widely recommended affordability guardrail for car buying is the 20/4/10 rule. It has three parts, and all three matter:

20% down. Put at least 20% of the car's price down in cash. New cars lose roughly a fifth of their value in the first year, so a 20% down payment keeps you from owing more than the car is worth the moment you drive it off the lot. Being "underwater" — owing more than the car is worth — is the trap that turns a fender-bender or a job loss into a financial crisis.

4-year loan, maximum. Finance for no more than 48 months. If you cannot afford the payment on a 4-year loan, you cannot afford the car — stretching the term to 5, 6 or 7 years just hides the problem behind a smaller payment while interest piles up. The worked example below shows exactly how much that stretch costs.

10% of gross income. Keep your total monthly car costs — loan payment, insurance, fuel and maintenance — under 10% of your gross monthly income. The strict version of the rule counts everything inside that 10%, not just the loan payment. That is the version the Car Affordability Calculator uses: it subtracts your insurance and running costs from the 10% budget first, and only the money left over becomes your loan payment.

The rule is conservative on purpose. Car dealers will happily approve you for far more — a lender's approval is a statement about what they can collect from you, not about what fits your life. The 20/4/10 rule is a statement about what fits your life.

Worked Example: A $72,000 Salary

Take someone earning $72,000 a year — $6,000 a month gross — planning to put 20% down, finance over 4 years at 7% APR, and pay $150 a month for insurance and running costs. Run those numbers through the Car Affordability Calculator:

That number surprises most people. On a $72,000 salary, the rule says the most car you should buy is about $23,490.11 — less than half the average new-car transaction price of $51,109 that Kelley Blue Book reported for October 2026. The gap is the point: the average new car is, by this measure, more car than the average earner should buy. The affordable answer at this income is a good used car, or a new compact car — compact cars averaged $28,030 in October 2026, still above the $23,490.11 ceiling, which is why the used market matters so much.

Notice what drives the result. The $600 monthly budget is not the loan payment — $150 of it is already spoken for by insurance and running costs, leaving $450 for the loan. If insurance and fuel actually cost $300 a month instead of $150, the affordable payment drops to $300 and the maximum price falls to about $15,660. Running costs are not a footnote; they are a third of the budget in this example. Be honest about them when you run your own numbers.

How Much Car at Your Income?

The same calculation, with the same assumptions (20% down, 4-year loan, 7% APR, $150 a month in insurance and running costs), gives these ceilings at four income levels:

Even at $100,000 a year, the ceiling is $35,670.17 — still well below the $51,109 average new-car price, and below the $37,895 average for a compact SUV. That is not a flaw in the rule; it is the rule doing its job. The average new car is expensive because the average new car sold is a large SUV or pickup truck, not because every buyer needs one. A $35,670.17 budget buys a solid compact SUV or a nearly new midsize car — and leaves room in the budget for everything else in life.

The table also shows how sensitive the answer is to running costs. At $100,000 with $300 a month in insurance and running costs instead of $150, the affordable payment falls to $533.33 and the maximum price drops to $27,840.13 — a $7,830.04 difference from the same salary. If you live somewhere with high insurance premiums or a long commute, run the calculator with your real numbers rather than the table's.

The Payment Is Not the Cost

The most common car-buying mistake is shopping by monthly payment. A dealer can make almost any car fit almost any payment by stretching the term — and the longer the term, the more you pay in total and the longer you owe more than the car is worth. The payment is the most manipulable number in the whole deal, which is why the 20/4/10 rule starts from your income and works backwards to a price, instead of starting from a payment and working forwards.

The second mistake is forgetting everything that is not the loan. Full-coverage car insurance averaged about $215 a month nationally in 2026, according to Insure.com — and it is higher for young drivers, drivers with tickets, and expensive or frequently stolen models. Fuel depends on your mileage and the car's efficiency: 1,000 miles a month at 25 miles per gallon and $3.50 a gallon is $140 a month. Maintenance, tyres, registration and the occasional repair add more. A realistic all-in figure for many drivers is $300–$400 a month on top of the loan payment, which is why the calculator subtracts running costs before sizing the loan. If you want a better insurance estimate for your situation, the Car Insurance Estimator can help, and the Fuel Cost Calculator will price your commute.

There is also the cost nobody puts in the advert: depreciation. A new car typically loses around 20% of its value in the first year and roughly half within five years. That is not a monthly bill, but it is real money — it is the reason the 20% down payment exists, and the reason a 2–4 year old used car is often the best value in the market. Someone else has already paid for the steepest part of the depreciation curve, and you get most of the car's useful life at a large discount.

Why the Loan Term Matters More Than the Payment

Here is what happens when the same $25,000 loan at 7% APR is stretched across different terms, run through the Auto Loan Calculator:

Stretching from 4 years to 6 years cuts the payment by $172.43 a month — but costs an extra $1,952.72 in interest, and keeps you paying for a 6-year-old car in its final year, when repair bills are at their highest. The 7-year loans now common at dealerships are worse still. Go back to the $72,000 earner from the worked example: on a 7-year term at the same $450 monthly payment, the calculator says they could "afford" a $37,269.72 car — $13,779.61 more car. But the total interest jumps from $2,807.91 to $7,984.22, an extra $5,176.31, the down payment rises to $7,453.94, and they would still owe money on a 7-year-old car. The longer term does not make the car more affordable; it makes the unaffordable car look affordable.

There is a second, quieter cost to long terms: negative equity. With a 6- or 7-year loan and a small down payment, you can owe more than the car is worth for years. If the car is written off, insurance pays its market value — not your loan balance — and you keep paying for a car you no longer own. Gap insurance covers that gap, but it is another cost, and needing it is a sign the loan structure is wrong.

New, Used, or Certified Pre-Owned?

At most incomes, the 20/4/10 ceiling points to the used market — and that is good news, not bad. A 3-year-old car has already absorbed the steepest depreciation, often costs 40–50% less than new, and still has most of its reliable life ahead of it, especially from a dependable brand. Certified pre-owned cars add a manufacturer-backed warranty and inspection to that discount, at a price between private-party used and new. The trade-off is interest: used-car loan rates are usually higher than new-car rates, and the car has fewer years of warranty left, so a pre-purchase inspection by an independent mechanic — typically $100–$200 — is money well spent.

New makes sense in a narrower set of cases: when the manufacturer is offering 0% or very low APR financing that a used loan cannot match, when you plan to keep the car for 10+ years (so depreciation matters less), or when the specific car you need is barely cheaper used than new, as happens with some trucks and popular models. Even then, run the 20/4/10 numbers first. A 0% loan on a car you cannot afford is still a car you cannot afford — the payment is just interest-free.

If the Number Disappoints You

Most people who run the calculator find the ceiling lower than they hoped. That is normal — and it is useful information, not a verdict. You have four levers, and they are all better than stretching the loan:

Save a bigger down payment. Every extra dollar down reduces the loan, the payment and the interest. It also protects you against negative equity. If the car you want is $5,000 above your ceiling, saving $5,000 more down is the honest way to close the gap.

Buy used, or buy smaller. Dropping one vehicle class — midsize SUV to compact SUV, for example — typically saves $10,000 or more. The October 2026 averages tell the story: compact cars at $28,030, compact SUVs at $37,895, midsize SUVs at $50,570 and full-size pickups at $67,912. The class you choose matters more than the brand.

Cut the running costs. A cheaper-to-insure model, a shorter commute, or a more fuel-efficient car all raise the ceiling, because the calculator subtracts running costs from the budget before sizing the loan. Getting insurance quotes before you buy — not after — can change the answer by thousands.

Wait and save. If the car you want is genuinely out of reach, the cheapest option is often keeping your current car a year longer while saving the would-be payment. A year of $450 monthly payments banked is $5,400 towards a down payment — and a year of no car payment is the best car deal there is.

Sources: Average new-vehicle transaction price $51,109 (October 2026, record high) and segment averages from Kelley Blue Book / Cox Automotive, November 10, 2026. Full-coverage insurance average of about $215/month from Insure.com, 2026. All affordability figures were produced by running the Car Affordability Calculator (20/4/10 rule: total car costs capped at 10% of gross monthly income, insurance and running costs subtracted first) and the Auto Loan Calculator (fixed-rate loan, monthly payments). Last reviewed: 13 November 2026.

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