The 20/4/10 Rule
The 20/4/10 rule states: put at least 20% down, finance for no more than 4 years, and keep total transportation costs (payment + insurance + gas) under 10% of gross income. This helps ensure you buy a car you can truly afford.
Affordability Formula
Max Payment = Monthly Income × 10% (transportation budget)
Max Car Price = Max Loan Amount + Down Payment
Affordability Guidelines
| Annual Income | Conservative | Moderate | Aggressive |
|---|---|---|---|
| $40,000 | $8,000 - $12,000 | $12,000 - $16,000 | $16,000 - $20,000 |
| $60,000 | $12,000 - $18,000 | $18,000 - $24,000 | $24,000 - $30,000 |
| $80,000 | $16,000 - $24,000 | $24,000 - $32,000 | $32,000 - $40,000 |
| $100,000 | $20,000 - $30,000 | $30,000 - $40,000 | $40,000 - $50,000 |
Frequently Asked Questions
How much of my income should go toward a car payment?
Most financial advisors recommend keeping your car payment under 10-15% of your monthly take-home pay. All transportation costs (payment, insurance, gas, maintenance) should stay under 15-20% of take-home pay.
Should I buy new or used?
Used cars (2-3 years old) offer the best value since they have already undergone the steepest depreciation. A certified pre-owned vehicle offers some warranty protection while saving 20-30% compared to new.