24 June 2026

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Car Buying Tips

How Much Car Can You Afford? The 20/4/10 Rule

budgetingcar-affordabilityfinancial-planning

The Monthly Payment Trap

Car salespeople love to ask "what monthly payment works for you?" It's a trap. Focusing on monthly payments obscures the total cost.

The 20/4/10 Rule

  • 20% down: protects you from being underwater immediately
  • 4-year term: if you need 60 or 72 months to afford the payment, the car is too expensive
  • 10% of income: total car expenses (payment, insurance, fuel, maintenance) shouldn't exceed 10% of gross monthly income

Example

$60K income = $5,000/month gross. 10% = $500 for car expenses. Subtract $120 insurance, $80 fuel, $50 maintenance = $250 left for payment. With 20% down and 48-month loan at 6.5%: roughly a $14,000 car.

Reality Check

The rule is conservative. A realistic approach might be 20/5/15 (20% down, 5-year term, 15% of income). The key: calculate total cost, not monthly payment. A $400 payment on 72 months costs $28,800 total. $500 on 48 months costs $24,000. Which is more affordable?

budgetingcar-affordabilityfinancial-planning
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1 Comment
DaveTheGearhead
DaveTheGearhead
@gearhead_dave · US
11 March 2025
Wish I'd read this before my first purchase. Stretched to a 72-month loan thinking low payment was a deal. Paid way too much in interest.
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Amy F.
Amy F.
@credit_repair_amy · US

Amy F. is a contributor to Auto Wes. Based in US.