How Much Car Can I Afford? The 20/4/10 Rule With Real Numbers
The 20/4/10 rule: 20% down, no more than a 4-year loan, and total transport costs under 10% of gross income. On a $75,000 salary that supports roughly a $26,000 car — a number that surprises people who shop by monthly payment.
Why dealers sell the payment, not the price
Because the payment is the one number they can shape at will. Stretch the term, fold in the trade-in, adjust the rate — a $38,000 car can be dressed up as a $499/month decision. The 20/4/10 rule exists to move the conversation back to numbers the dealer can’t stretch:
- 20% down — so you’re never underwater the moment you drive off (cars lose ~20% in year one).
- 4 years maximum — the term cap that keeps total interest honest and ends payments before major repairs begin.
- 10% of gross monthly income for all transport — payment plus insurance plus fuel. The cap that protects the rest of your budget.
How much car you can afford by income
Assuming ~$120/month insurance, a 7.5% APR, 48-month term, and 20% down — verify any row in the loan calculator:
| Gross income | Transport cap (10%) | Payment budget | Amount financed | Car price (with 20% down) |
|---|---|---|---|---|
| $50,000 | $417/mo | ~$297 | $12,270 | ~$15,300 |
| $75,000 | $625/mo | ~$505 | $20,886 | ~$26,100 |
| $100,000 | $833/mo | ~$713 | $29,502 | ~$36,900 |
If those numbers feel low against what you see in driveways, that’s the point — the average new-car transaction now runs near $48,000, and the average payment north of $700, financed by exactly the long terms the rule forbids. The rule isn’t wrong; the average is.
Why 72-month car loans cost so much
The same $26,000 car, financed at 7.5% (verify in the loan calculator):
- 48 months: higher payment, ~$4,200 interest, and you own a 4-year-old car free and clear.
- 72 months: payment drops ~$180, interest climbs past $6,400 — and years 5–6 combine loan payments with out-of-warranty repair bills, the exact months people trade in at a loss and start over. That restart loop, repeated over a driving lifetime, quietly costs more than any single car.
How to apply the 20/4/10 rule in real life
- Can’t reach 20% down? Delay the purchase, not the rule. A dated savings goal of even $150/month closes most down-payment gaps within a year — while your current car depreciates the seller’s asset, not yours.
- High-insurance driver? (young, urban, or spotty record) Your insurance eats more of the 10% cap, so the car budget shrinks. That’s the rule correctly pricing your total cost of driving.
- Cash buyer? The 10% cap still applies — a paid-off car that devours 15% of gross income in insurance and fuel is still too much car.
- The upgrade itch, quantified: the ~$180/month gap between a sensible and a stretch car, invested at 7% for 20 years, is about $94,000. Every car upgrade is priced in future money; the rule just makes the price tag visible.
Frequently asked questions
What is the 20/4/10 rule for buying a car?
Put at least 20% down, finance for no more than 4 years, and keep total transportation costs — payment, insurance, fuel — under 10% of gross monthly income. Each limit blocks a different failure: instant negative equity, endless loans, and budget creep.
How much car can I afford on a $60,000 salary?
By 20/4/10: 10% of gross is $500/month for all transport. After ~$120 insurance, roughly $380 supports about $15,700 financed at 7.5% over 48 months — call it a $19,000–20,000 car with 20% down. Payment-first shopping would 'approve' you for double that.
Is a 72- or 84-month car loan ever okay?
It's how the average new-car payment passed $700. Long terms mean years of owing more than the car is worth, and often overlapping repair costs with loan payments. If a car only fits your budget at 72+ months, the honest conclusion is that it doesn't fit your budget.
New or used under this rule?
The rule is agnostic — it prices the total, not the age. In practice it pushes most incomes toward late-model used cars, which is also where depreciation math is kindest: a 3-year-old car has already surrendered roughly a third of its original value to someone else.