20% Rule vs 10% Car Payment Rule
The **20% rule** (total car costs under 20% of gross) is aggressive when insurance and fuel stack on top of payment. The **10% payment rule** is conservative—better for high-cost metros and other debt.
Step by step
1. Use gross income
Rules reference pre-tax pay—not take-home.
2. Add insurance and fuel
Payment-only rules understate true ownership cost.
3. Stress rate
Run affordability at plus 2% APR if rates are volatile.
20% total vs 10% payment
Shorter loan terms make the same car price feel tighter monthly.
- 20% all-in: Includes payment, insurance, gas, maintenance cap.
- 10% payment: Lower payment ceiling; more room for housing and savings.
Use our calculators
Common mistakes
- Ignoring student loans in DTI
- Financing 84 months to pass payment rule
FAQ
Which rule do lenders use?
Lenders use DTI—often 36-50% total debt, not car-specific percent.