How Much Car Can I Afford? Use the 20/4/10 Rule
Use the 20/4/10 rule to figure out how much car you can afford: 20% down, a loan of 4 years or less, and total car costs under 10% of income. Examples and tips inside.
A car is the second-biggest purchase most people make, and one of the easiest to overspend on. Dealers focus on the monthly payment; you should focus on the total cost. The 20/4/10 rule is a simple guardrail.
The 20/4/10 rule
- 20% down payment (or more)
- 4 years (48 months) maximum loan term
- 10% of your gross monthly income, maximum, for total car costs: payment, insurance, and ideally fuel and maintenance too
It's conservative on purpose. Cars lose value quickly, and long, low-down loans can leave you owing more than the car is worth.
Example
You earn $60,000 a year, which is $5,000 a month before taxes.
- 10% of income: $500 per month for all car costs.
- Insurance $150 and fuel/maintenance $100 leaves about $250 for a loan payment.
- A 48-month loan at 7% with $250 payments supports a loan of roughly $10,400.
- With a 20% down payment (about $2,600), you can afford a car priced around $13,000, plus taxes and fees.
That may be lower than you expected, which is the point. Many people find a reliable used car fits the rule far better than a new one.
Why long loans are risky
72- and 84-month auto loans are common because they shrink the monthly payment, but:
- You pay much more interest overall.
- You're more likely to be "upside down" (owing more than the car is worth), which is a problem if the car is totaled or you want to sell.
- The loan may outlast the warranty, so you're making payments and paying for repairs at the same time.
The total cost of owning a car
| Cost | What to check |
|---|---|
| Depreciation | New cars lose a large share of their value in the first few years |
| Insurance | Get quotes before you buy; some models cost much more to insure |
| Fuel or charging | Estimate from your typical miles per month |
| Maintenance and repairs | Older cars cost more to maintain; set money aside monthly |
| Registration, taxes, fees | Vary by state |
How to get a better deal
- Get pre-approved for a loan from a bank or credit union before visiting a dealer. It gives you a rate to beat.
- Negotiate the out-the-door price, not the monthly payment.
- Keep the trade-in separate from the purchase negotiation.
- Skip add-ons you don't need (paint protection, VIN etching). Extended warranties and GAP insurance are often cheaper elsewhere, if you need them at all.
- Consider certified pre-owned for a balance of price and reliability.
- Improve your credit first, since your score heavily affects your rate. See how credit scores work.
Start a car sinking fund
The best car payment is the one you make to yourself. Once your current car is paid off, keep "paying" the same amount into savings. When it's time to replace it, you'll have a large down payment or be able to pay cash. See sinking funds.
Key takeaways
- 20/4/10: 20% down, loan of 4 years or less, total car costs under 10% of gross income.
- Focus on total cost and out-the-door price, not the monthly payment.
- Long loans cost more and raise the risk of owing more than the car is worth.
- Get pre-approved and consider reliable used cars.
Example uses a hypothetical 7% APR. Your rate depends on credit, term and lender.
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